1.
Radiology
–
Radiology is a specialty that uses medical imaging to diagnose and treat diseases seen within the body. Interventional radiology is the performance of medical procedures with the guidance of imaging technologies, the acquisition of medical images is usually carried out by the Radiographer, often known as a Radiologic Technologist. Depending on location, the Diagnostic Radiologist, or Reporting Radiographer, then interprets or reads the images and produces a report of their findings and this report is then transmitted to the Clinician who requested the imaging, either routinely or emergently. Radiographs are produced by transmitting X-rays through a patient, the X-rays are projected through the body onto a detector, an image is formed based on which rays pass through versus those that are absorbed or scattered in the patient. Röntgen discovered X-rays on November 8,1895 and received the first Nobel Prize in Physics for their discovery in 1901, in film-screen radiography, an X-ray tube generates a beam of X-rays, which is aimed at the patient. The film is then developed chemically and an image appears on the film, film-screen radiography is being replaced by computed radiography but more recently by digital radiography and the EOS imaging. In the two latest systems, the X-rays strike sensors that converts the signals generated into digital information, in digital radiography the sensors shape a plate, but in the EOS system, which is a slot-scanning system, a linear sensor vertically scans the patient. Plain radiography was the imaging modality available during the first 50 years of radiology. Due to its availability, speed, and lower costs compared to other modalities, also despite the large amount of data in CT scans, MR scans and other digital-based imaging, there are many disease entities in which the classic diagnosis is obtained by plain radiographs. Examples include various types of arthritis and pneumonia, bone tumors, fractures, congenital skeletal anomalies, mammography and DXA are two applications of low energy projectional radiography, used for the evaluation for breast cancer and osteoporosis, respectively. Fluoroscopy and angiography are special applications of X-ray imaging, in which a fluorescent screen and this allows real-time imaging of structures in motion or augmented with a radiocontrast agent. Two radiocontrast agents are presently in common use, barium sulfate is given orally or rectally for evaluation of the GI tract. Iodine, in multiple forms, is given by oral, rectal, intra-arterial or intravenous routes. Iodine contrast may also be concentrated in areas more or less than in normal tissues. CT imaging uses X-rays in conjunction with computing algorithms to image the body, in CT, an X-ray tube opposite an X-ray detector in a ring-shaped apparatus rotate around a patient, producing a computer-generated cross-sectional image. CT is acquired in the plane, with coronal and sagittal images produced by computer reconstruction. Radiocontrast agents are used with CT for enhanced delineation of anatomy. Although radiographs provide higher resolution, CT can detect more subtle variations in attenuation of X-rays
Radiology
–
A radiologist interprets medical images on a modern
picture archiving and communication system (PACS) workstation. San Diego, CA, 2010.
Radiology
–
Madura foot X-ray
Radiology
–
Radiography of knee in DR-machine at Sandnessjøen Hospital, Norway.
Radiology
–
Image from a
CT scan of the brain
2.
Musculoskeletal system
–
The human musculoskeletal system is an organ system that gives humans the ability to move using their muscular and skeletal systems. The musculoskeletal system provides form, support, stability, and movement to the body and it is made up of the bones of the skeleton, muscles, cartilage, tendons, ligaments, joints, and other connective tissue that supports and binds tissues and organs together. The musculoskeletal systems primary functions include supporting the body, allowing motion, the skeletal portion of the system serves as the main storage system for calcium and phosphorus and contains critical components of the hematopoietic system. This system describes how bones are connected to other bones and muscle fibers via connective tissue such as tendons, the bones provide stability to the body. Muscles keep bones in place and also play a role in the movement of bones, to allow motion, different bones are connected by joints. Cartilage prevents the bone ends from rubbing directly onto each other, muscles contract to move the bone attached at the joint. There are, however, diseases and disorders that may affect the function. These diseases can be difficult to due to the close relation of the musculoskeletal system to other internal systems. The musculoskeletal system refers to the system having its muscles attached to a skeletal system and is necessary for humans to move to a more favorable position. Complex issues and injuries involving the musculoskeletal system are handled by a physiatrist or an orthopaedic surgeon. The skeletal system serves many important functions, it provides the shape and form for the body, support and protection, allows bodily movement, produces blood for the body, the number of bones in the human skeletal system is a controversial topic. Humans are born with over 300 bones, however, many bones fuse together between birth and maturity, as a result, an average adult skeleton consists of 206 bones. The number of bones varies according to the used to derive the count. While some consider certain structures to be a bone with multiple parts. There are five classifications of bones. These are long bones, short bones, flat bones, irregular bones, the human skeleton is composed of both fused and individual bones supported by ligaments, tendons, muscles and cartilage. It is a structure with two distinct divisions, the axial skeleton, which includes the vertebral column, and the appendicular skeleton. The skeletal system serves as a framework for tissues and organs to attach themselves to and this system acts as a protective structure for vital organs
Musculoskeletal system
–
The body contains three types of muscle tissue: (a) skeletal muscle, (b) smooth muscle, and (c) cardiac muscle.
Musculoskeletal system
–
Features of the human activity system from the 1911 Encyclopædia Britannica
Musculoskeletal system
–
On the anterior and posterior views of the muscular system above, superficial muscles (those at the surface) are shown on the right side of the body while deep muscles (those underneath the superficial muscles) are shown on the left half of the body. For the legs, superficial muscles are shown in the anterior view while the posterior view shows both superficial and deep muscles.
3.
Screening (medicine)
–
Screening, in medicine, is a strategy used in a population to identify the possible presence of an as-yet-undiagnosed disease in individuals without signs or symptoms. This can include individuals with pre-symptomatic or unrecognized symptomatic disease, as such, screening tests are somewhat unusual in that they are performed on persons apparently in good health. Screening interventions are designed to identify disease in a community early, thus enabling earlier intervention and management in the hope to reduce mortality and suffering from a disease. For these reasons, a test used in a program, especially for a disease with low incidence. Several types of screening exist, universal screening involves screening of all individuals in a certain category, case finding involves screening a smaller group of people based on the presence of risk factors. Screening interventions are not designed to be diagnostic, and often have significant rates of false positive and false negative results. In 1968 the World Health Organization published guidelines on the Principles and practice of screening for disease, the principles are still broadly applicable today, The condition should be an important health problem. There should be a treatment for the condition, facilities for diagnosis and treatment should be available. There should be a latent stage of the disease, There should be a test or examination for the condition. The test should be acceptable to the population, the natural history of the disease should be adequately understood. There should be a policy on whom to treat. The total cost of finding a case should be balanced in relation to medical expenditure as a whole. Case-finding should be a process, not just a once. • The objectives of screening should be defined at the outset, • There should be a defined target population. • There should be evidence of screening programme effectiveness. • The programme should integrate education, testing, clinical services, • There should be quality assurance, with mechanisms to minimize potential risks of screening. • The programme should ensure informed choice, confidentiality and respect for autonomy, • The programme should promote equity and access to screening for the entire target population. • Programme evaluation should be planned from the outset, • The overall benefits of screening should outweigh the harm
Screening (medicine)
–
A coal miner completes a screening survey for
coalworker's pneumoconiosis.
Screening (medicine)
–
A mobile clinic used to screen coal miners at risk of
black lung disease
4.
X-ray
–
X-radiation is a form of electromagnetic radiation. Most X-rays have a wavelength ranging from 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz, X-ray wavelengths are shorter than those of UV rays and typically longer than those of gamma rays. Spelling of X-ray in the English language includes the variants x-ray, xray, X-rays with high photon energies are called hard X-rays, while those with lower energy are called soft X-rays. Due to their ability, hard X-rays are widely used to image the inside of objects, e. g. in medical radiography. The term X-ray is metonymically used to refer to an image produced using this method. Since the wavelengths of hard X-rays are similar to the size of atoms they are useful for determining crystal structures by X-ray crystallography. By contrast, soft X-rays are easily absorbed in air, the length of 600 eV X-rays in water is less than 1 micrometer. There is no consensus for a definition distinguishing between X-rays and gamma rays, one common practice is to distinguish between the two types of radiation based on their source, X-rays are emitted by electrons, while gamma rays are emitted by the atomic nucleus. This definition has problems, other processes also can generate these high-energy photons. One common alternative is to distinguish X- and gamma radiation on the basis of wavelength, with radiation shorter than some arbitrary wavelength, such as 10−11 m and this criterion assigns a photon to an unambiguous category, but is only possible if wavelength is known. Occasionally, one term or the other is used in specific contexts due to precedent, based on measurement technique. Thus, gamma-rays generated for medical and industrial uses, for radiotherapy, in the ranges of 6–20 MeV. X-ray photons carry enough energy to ionize atoms and disrupt molecular bonds and this makes it a type of ionizing radiation, and therefore harmful to living tissue. A very high radiation dose over a period of time causes radiation sickness. In medical imaging this increased risk is generally greatly outweighed by the benefits of the examination. The ionizing capability of X-rays can be utilized in treatment to kill malignant cells using radiation therapy. It is also used for material characterization using X-ray spectroscopy, hard X-rays can traverse relatively thick objects without being much absorbed or scattered. For this reason, X-rays are widely used to image the inside of visually opaque objects, the most often seen applications are in medical radiography and airport security scanners, but similar techniques are also important in industry and research
X-ray
–
Spectrum of the X-rays emitted by an X-ray tube with a
rhodium target, operated at 60
kV. The smooth, continuous curve is due to
bremsstrahlung, and the spikes are
characteristic K lines for rhodium atoms.
X-ray
–
X-rays are part of the
electromagnetic spectrum, with wavelengths shorter than
visible light. Different applications use different parts of the X-ray spectrum.
X-ray
–
A
chest radiograph of a female, demonstrating a
hiatus hernia
X-ray
–
An arm radiograph, demonstrating broken
ulna and
radius with implanted
internal fixation.
5.
Radiographer
–
Radiographers are infrequently, and almost always erroneously, known as x-ray technicians. Radiographers work in public and private healthcare and can be physically located in any setting where appropriate diagnostic equipment is located. Their practice varies country to country and can vary between hospitals in the same country. Until around 1918 radiographers were known as skiagraphers, the term is derived from the Ancient Greek words for shadow and it is not uncommon for radiographers to now conduct procedures which would have previously been undertaken by a cardiologist, urologist, radiologist or oncologist autonomously. Contrary to what could be inferred, radiographers conduct and contribute to investigations which are not necessarily radiological in nature, e. g. sonography, Radiographers often have opportunities to enter military service due to their role in healthcare. As with most other occupations in the field many radiographers have rotating shifts that include night duties. Radiography is a deeply diverse profession with many different modalities and specialities, as a result of this the typical career pathway for a radiographer is hard to summarise. Upon qualifying it is common for radiographers to focus solely on plain film radiography before specialising in any one chosen modality, after a number of years in the profession, non-imaging based roles often become open and radiographers may then move into these positions. Generally, imaging modalities are all diagnostic, all have the potential to be used therapeutically in order to deliver an intervention, modalities include but are not limited to, 1Prefixes such as paediatric, geriatric, trauma are routinely placed used in conjunction with professional titles. 2This list of technologies is not exhaustive, non-imaging modalities vary, and are often undertaken in addition to imaging modalities. They commonly include, Academia - Education role, Clinical Management - Clinical managerial role which can be varied, may include managing audits, rotas, department budgets, etc. Medical Physics - Multidisciplinary role ensuring the correct calibration of and most efficient use of diagnostic equipment, PACS Management - Managerial role concerned with maintaining and supervising appropriate and correct use of the RIS and PACS systems. Radiation Protection - A managerial role concerned with monitoring the level of ionising radiation absorbed by anyone who comes into contact with ionising radiation at their site, Reporting Radiography - A clinical role involved with interpretation of radiographs and various other radiological media for diagnosis. Education varies worldwide due to limitations on scope of practice. In Germany radiographers must complete a 3-year, self-funded programme before they qualify as a Medizinisch-technischer Radiologieassistent, only after qualifying do radiographers in Germany fulfil the requirements to practise as a fully qualified MTR. Similar to other countries, they work within the areas of radiography diagnostics, radiation therapy, radiation dosimeters, Radiographers in the Republic of Ireland must be registered with CORU before they can practice in the Republic of Ireland. Student radiographers training in the ROI will typically study for 4 years on a bachelors degree program. Applications for registration with qualifications outside of this are considered on an individual basis, the professional body representing Radiographers in the ROI is the Irish Institute of Radiography and Radiation Therapy
Radiographer
–
A Radiographer with a radiographic examination table and X-Ray tube.
Radiographer
–
A US Navy Radiographer simulates a CT examination.
6.
Electromagnetic radiation
–
In physics, electromagnetic radiation refers to the waves of the electromagnetic field, propagating through space carrying electromagnetic radiant energy. It includes radio waves, microwaves, infrared, light, ultraviolet, X-, classically, electromagnetic radiation consists of electromagnetic waves, which are synchronized oscillations of electric and magnetic fields that propagate at the speed of light through a vacuum. The oscillations of the two fields are perpendicular to other and perpendicular to the direction of energy and wave propagation. The wavefront of electromagnetic waves emitted from a point source is a sphere, the position of an electromagnetic wave within the electromagnetic spectrum can be characterized by either its frequency of oscillation or its wavelength. Electromagnetic waves are produced whenever charged particles are accelerated, and these waves can interact with other charged particles. EM waves carry energy, momentum and angular momentum away from their source particle, quanta of EM waves are called photons, whose rest mass is zero, but whose energy, or equivalent total mass, is not zero so they are still affected by gravity. Thus, EMR is sometimes referred to as the far field, in this language, the near field refers to EM fields near the charges and current that directly produced them, specifically, electromagnetic induction and electrostatic induction phenomena. In the quantum theory of electromagnetism, EMR consists of photons, quantum effects provide additional sources of EMR, such as the transition of electrons to lower energy levels in an atom and black-body radiation. The energy of a photon is quantized and is greater for photons of higher frequency. This relationship is given by Plancks equation E = hν, where E is the energy per photon, ν is the frequency of the photon, a single gamma ray photon, for example, might carry ~100,000 times the energy of a single photon of visible light. The effects of EMR upon chemical compounds and biological organisms depend both upon the power and its frequency. EMR of visible or lower frequencies is called non-ionizing radiation, because its photons do not individually have enough energy to ionize atoms or molecules, the effects of these radiations on chemical systems and living tissue are caused primarily by heating effects from the combined energy transfer of many photons. In contrast, high ultraviolet, X-rays and gamma rays are called ionizing radiation since individual photons of high frequency have enough energy to ionize molecules or break chemical bonds. These radiations have the ability to cause chemical reactions and damage living cells beyond that resulting from simple heating, Maxwell derived a wave form of the electric and magnetic equations, thus uncovering the wave-like nature of electric and magnetic fields and their symmetry. Because the speed of EM waves predicted by the wave equation coincided with the speed of light. Maxwell’s equations were confirmed by Heinrich Hertz through experiments with radio waves, according to Maxwells equations, a spatially varying electric field is always associated with a magnetic field that changes over time. Likewise, a varying magnetic field is associated with specific changes over time in the electric field. In an electromagnetic wave, the changes in the field are always accompanied by a wave in the magnetic field in one direction
Electromagnetic radiation
7.
X-ray generator
–
An X-ray generator is a device that produces X-rays. It is commonly used in a variety of applications including medicine, fluorescence, electronic assembly inspection, in medical applications, X-ray generators are used by radiographers to acquire x-ray images of the internal structures of living organisms, and also in sterilization. X-rays are typically generated by an X-ray tube, when the electrons collide with the target, about 1% of the resulting energy is emitted as X-rays, with the remaining 99% released as heat. Due to the energy of the electrons that reach relativistic speeds the target is usually made of tungsten even if other material can be used particularly in XRF applications. A cooling system is necessary to cool the anode, many X-ray generators use water or oil recirculating systems, the discovery of X-rays came from experimenting with Crookes tubes, an early experimental electrical discharge tube invented by English physicist William Crookes around 1869-1875. In 1895, Wilhelm Röntgen discovered X-rays emanating from Crookes tubes, one of the first X-ray photographs was made of the hand of Röntgens wife. The image displayed both her wedding ring and bones, on January 18,1896 an X-ray machine was formally displayed by H. L. Smith. A fully functioning unit was introduced to the public at the 1904 Worlds Fair by Clarence Dally, in the 1940s and 1950s, X-ray machines were used in stores to help sell footwear. These were known as Shoe-fitting fluoroscopes, however, as the harmful effects of X-ray radiation were properly considered, they finally fell out of use. Shoe-fitting use of the device was first banned by the state of Pennsylvania in 1957, together with Robert J. Van de Graaff, John G. Trump developed one of the first million-volt X-ray generators. X-ray photons are produced by a beam that is accelerated to a very high speed. The electrons that make up the beam are emitted from a cathode filament. The electrons are focused and accelerated by an electrical field towards an angled anode target. The point where the beam strikes the target is called the focal spot. Most of the energy contained in the electron beam is converted to heat, but around 1% of the energy is converted into X-ray photons. There is a round window in the X-ray tube directly above the angled target. This window allows the X-rays to exit the tube with little attenuation while maintaining a vacuum seal required for the X-ray tube operation. Other than the tube window or port the remaining portion of the x-ray tube housing is lined with lead to absorb all remaining x-rays not usable for image creation
X-ray generator
–
A radiology room table. The X-ray housing is turned by 90° for a chest radiography
X-ray generator
–
XR150 - Portable pulsed X-ray Battery Powered X-ray Generator used in Security.
X-ray generator
–
Surgical mobiles can produce images continuously.
X-ray generator
–
Hand-luggage inspection machine at Berlin Schönefeld Airport.
8.
X-ray detector
–
X-ray detectors are devices used to measure the flux, spatial distribution, spectrum, and/or other properties of X-rays. Detectors can be divided into two categories, imaging detectors and dose measurement devices. X-rays are partially blocked by dense tissues such as bone, areas where the X-rays strike darken when developed, causing bones to appear lighter than the surrounding soft tissue. Contrast compounds containing barium or iodine, which are radiopaque, can be ingested in the tract or injected in the artery or veins to highlight these vessels. The contrast compounds have high atomic numbered elements in them that essentially block the X-rays, in the pursuit of nontoxic contrast materials, many types of high atomic number elements were evaluated. Modern contrast material has improved and, while there is no way to determine who may have a sensitivity to the contrast, typical x-ray film contains silver halide crystal grains, typically primarily silver bromide. Grain size and composition can be adjusted to affect the film properties, when the film is exposed to radiation the halide is ionised and free electrons are trapped in crystal defects. Silver ions are attracted to these defects and reduced, creating clusters of transparent silver atoms, in the developing process these are converted to opaque silver atoms which form the viewable image, darkest where the most radiation was detected. Further developing steps stabilise the sensitised grains and remove unsensitised grains to prevent further exposure, the first radiographs were made by the action of X-rays on sensitized glass photographic plates. X-ray film soon replaced the glass plates, and film has been used for decades to acquire medical and industrial images, gradually, digital computers gained the ability to store and display enough data to make digital imaging possible. The metal silver is a non-renewable resource although silver can easily be reclaimed from spent X-ray film, where X-ray films required wet processing facilities, newer digital technologies do not. Digital archiving of images also saves physical storage space, because photographic plates are sensitive to X-rays, they provide a means of recording the image, but they also require much X-ray exposure. An alternative method of recording the X-rays is the use of photostimulated luminescence, a photostimulable phosphor plate is used in place of the photographic plate. After the plate is X-rayed, excited electrons in the phosphor material remain trapped in colour centres in the crystal lattice until stimulated by a laser beam passed over the plate surface, the PSP plate can be reused, and existing X-ray equipment requires no modification to use them. X-rays are also used in procedures such as angiography or contrast studies of the hollow organs using fluoroscopy. Angioplasty, medical interventions of the system, rely heavily on X-ray-sensitive contrast to identify potentially treatable lesions. Solid state detectors use semiconductors to detect x-rays, direct digital detectors are so-called because they directly convert x-ray photons to electrical charge and thus a digital image. Indirect systems may have intervening steps for example first converting x-ray photons to visible light, both systems typically use thin film transistors to read out and convert the electronic signal to a digital image
X-ray detector
–
Modern x-ray machine with digital detectors at Sandnessjøen Hospital,
Sandnessjøen, Norway
X-ray detector
–
Fishbone pierced in the upper esophagus. Right image without contrast medium, left image during swallowing with contrast medium.
X-ray detector
–
radiograph taken during
cholecystectomy
9.
Photographic film
–
This article is mainly concerned with still photography film. For motion picture film, please see film stock, photographic film is a strip or sheet of transparent plastic film base coated on one side with a gelatin emulsion containing microscopically small light-sensitive silver halide crystals. The sizes and other characteristics of the crystals determine the sensitivity, contrast, the emulsion will gradually darken if left exposed to light, but the process is too slow and incomplete to be of any practical use. Instead, a short exposure to the image formed by a camera lens is used to produce only a very slight chemical change. This creates an invisible latent image in the emulsion, which can be developed into a visible photograph. In addition to light, all films are sensitive to ultraviolet, X-rays. Unmodified silver halide crystals are only to the blue part of the visible spectrum. This problem was overcome with the discovery that certain dyes, called sensitizing dyes, first orthochromatic and finally panchromatic films were developed. Panchromatic film renders all colors in shades of gray approximately matching their subjective brightness, by similar techniques special-purpose films can be made sensitive to the infrared region of the spectrum. In black-and-white photographic film there is one layer of silver halide crystals. When the exposed silver halide grains are developed, the silver halide crystals are converted to metallic silver, color film has at least three sensitive layers, incorporating different combinations of sensitizing dyes. Typically the blue-sensitive layer is on top, followed by a filter layer to stop any remaining blue light from affecting the layers below. Next come a green-and-blue sensitive layer, and a sensitive layer. During development, the silver halide crystals are converted to metallic silver. Because the by-products are created in direct proportion to the amount of exposure and development, following development, the silver is converted back to silver halide crystals in the bleach step. It is removed from the film during the process of fixing the image on the film with a solution of ammonium thiosulfate or sodium thiosulfate, fixing leaves behind only the formed color dyes, which combine to make up the colored visible image. Later color films, like Kodacolor II, have as many as 12 emulsion layers, the earliest practical photographic process, the daguerreotype, introduced in 1839, did not use film. The light-sensitive chemicals were formed on the surface of a copper sheet
Photographic film
–
135 Film Cartridge with DX barcode (top) and DX CAS code on the black and white grid below the barcode. The CAS code shows the ISO, number of exposures, exposure latitude (+3/−1 for print film).
Photographic film
–
Advertisement for Ansco Speedex Film, 1922.
Photographic film
–
DX film edge barcode
10.
Two dimensional
–
In physics and mathematics, two-dimensional space is a geometric model of the planar projection of the physical universe. The two dimensions are commonly called length and width, both directions lie in the same plane. A sequence of n numbers can be understood as a location in n-dimensional space. When n =2, the set of all locations is called two-dimensional space or bi-dimensional space. Each reference line is called an axis or just axis of the system. The coordinates can also be defined as the positions of the projections of the point onto the two axes, expressed as signed distances from the origin. The idea of system was developed in 1637 in writings by Descartes and independently by Pierre de Fermat. Both authors used a single axis in their treatments and have a length measured in reference to this axis. The concept of using a pair of axes was introduced later, after Descartes La Géométrie was translated into Latin in 1649 by Frans van Schooten and these commentators introduced several concepts while trying to clarify the ideas contained in Descartes work. Later, the plane was thought of as a field, where any two points could be multiplied and, except for 0, divided and this was known as the complex plane. The complex plane is called the Argand plane because it is used in Argand diagrams. These are named after Jean-Robert Argand, although they were first described by Norwegian-Danish land surveyor, Argand diagrams are frequently used to plot the positions of the poles and zeroes of a function in the complex plane. In mathematics, analytic geometry describes every point in space by means of two coordinates. Two perpendicular coordinate axes are given which cross each other at the origin and they are usually labeled x and y. Another widely used system is the polar coordinate system, which specifies a point in terms of its distance from the origin. In two dimensions, there are infinitely many polytopes, the polygons, the first few regular ones are shown below, The Schläfli symbol represents a regular p-gon. The regular henagon and regular digon can be considered degenerate regular polygons and they can exist nondegenerately in non-Euclidean spaces like on a 2-sphere or a 2-torus. There exist infinitely many non-convex regular polytopes in two dimensions, whose Schläfli symbols consist of rational numbers and they are called star polygons and share the same vertex arrangements of the convex regular polygons
Two dimensional
–
Bi-dimensional
Cartesian coordinate system
11.
Projectional radiography
–
Projectional radiography is the practice of producing two-dimensional images using x-ray radiation. Radiographic exams are performed by radiographers, trained, licensed medical professionals. Projectional radiography is the cornerstone of modern medical imaging, and can be used to image almost every part of the human body, mammography, DXA and dental radiography are specialized variants of projectional radiography. Computed tomography also uses x-radiation, but its different image acquisition parameters allow for images to be acquired in the axial plane, projectional radiography relies on the characteristics of x-ray radiation and knowledge of how it interacts with human tissue to create diagnostic images. X-rays are a form of ionizing radiation, meaning it has sufficient energy to remove electrons from an atom, thus giving it a charge. Ionizing radiation has sufficient energy to human tissue. When an exposure is made, x-ray radiation exits the tube as what is known as the primary beam, when the primary beam passes through the body, some of the radiation is absorbed in a process known as attenuation. Anatomy that is denser has a rate of attenuation than anatomy that is less dense. What remains of the beam after attenuation is known as the remnant beam. The remnant beam is responsible for exposing the image receptor, areas on the image receptor that receive the most radiation will be more heavily exposed, and therefore will be processed as being darker. Conversely, areas on the receptor that receive the least radiation will be less exposed. This is why bone, which is dense, process as being ‘white’ on radio graphs, and the lungs. Radiographic density is the measure of overall darkening of the image, density is a logarithmic unit that describes the ratio between light hitting the film and light being transmitted through the film. A higher radiographic density represents more opaque areas of the film, with digital imaging, however, density may be referred to as brightness. The brightness of the radiograph in digital imaging is determined by computer software, contrast is defined as the difference in radiographic density between adjacent portions of the image. The range between black and white on the final radiograph, high contrast, or short-scale contrast, means there is little gray on the radiograph, and there are fewer gray shades between black and white. Low contrast, or long-scale contrast, means there is much gray on the radiograph, closely related to radiographic contrast is the concept of exposure latitude. Images having a short-scale of contrast will have narrow exposure latitude, images having long-scale contrast will have a wide exposure latitude, that is, the radiographer will be able to utilize a broader range of technical factors to produce a diagnostic-quality image
Projectional radiography
–
AP and Lateral Elbow X-Ray
Projectional radiography
–
X-ray under examination
Projectional radiography
–
Philips Digital X-Ray Equipment
12.
Industrial radiography
–
Industrial radiography is a method of non-destructive testing where many types of manufactured components can be examined to verify the internal structure and integrity of the specimen. Industrial Radiography can be performed utilizing either X-rays or gamma rays, both are forms of electromagnetic radiation. The difference between forms of electromagnetic energy is related to the wavelength. X and gamma rays have the shortest wavelength and this property leads to the ability to penetrate, travel through, Radiography started in 1895 with the discovery of X-rays, a type of electromagnetic radiation. Soon after the discovery of X-rays, radioactivity was discovered, by using radioactive sources such as radium, far higher photon energies could be obtained than those from normal X-ray generators. Soon these found various applications, with one of the earliest users being Loughborough College, X-rays and gamma rays were put to use very early, before the dangers of ionizing radiation were discovered. After World War II new isotopes such as caesium-137, iridium-192 and cobalt-60 became available for industrial radiography, gamma radiation sources, most commonly iridium-192 and cobalt-60, are used to inspect a variety of materials. The vast majority of concerns the testing and grading of welds on pressurized piping, pressure vessels, high-capacity storage containers, pipelines. Other tested materials include concrete, welders test coupons, machined parts, plate metal, non-metal components such as ceramics used in the aerospace industries are also regularly tested. Theoretically, industrial radiographers could radiograph any solid, flat material or any hollow cylindrical or spherical object, the result is a two-dimensional projection of the part onto the film, producing a latent image of varying densities according to the amount of radiation reaching each area. It is known as a graph, as distinct from a photograph produced by light. Because film is cumulative in its response, relatively weak radiation can be detected by prolonging the exposure until the film can record an image that will be visible after development, the radiograph is examined as a negative, without printing as a positive as in photography. This is because, in printing, some of the detail is always lost, before commencing a radiographic examination, it is always advisable to examine the component with ones own eyes, to eliminate any possible external defects. Defects such as delaminations and planar cracks are difficult to detect using radiography, very important as most construction standards permit some level of defect acceptance, depending on the type and size of the defect. For purposes of inspection, including weld inspection, there exist several exposure arrangements, first, there is the panoramic, one of the four single-wall exposure/single-wall view arrangements. This exposure is created when the places the source of radiation at the center of a sphere, cone. Depending upon client requirements, the radiographer would then place film cassettes on the outside of the surface to be examined and this exposure arrangement is nearly ideal – when properly arranged and exposed, all portions of all exposed film will be of the same approximate density. The major disadvantage of the panoramic is that it may be impractical to reach the center of the item or the source may be too weak to perform in this arrangement
Industrial radiography
–
A portable wireless controlled battery powered X-ray generator for use in
non-destructive testing and security.
13.
Airport security
–
Airport security refers to the techniques and methods used in protecting passengers, staff and planes which use the airports from accidental/malicious harm, crime and other threats. Large numbers of pass through airports every day. This presents potential targets for terrorism and other forms of crime because of the number of people located in one place, Airport security attempts to prevent any threats or potentially dangerous situations from arising or entering the country. If airport security does succeed then the chances of any situation, illegal items or threats entering into an aircraft. While some countries may have an agency that protects all of their airports, the primary personnel will vary and can include, A police force hired and dedicated to the airport e. g. Travelers are screened by metal detectors, explosive detection machines used include X-ray machines and explosives trace-detection portal machines. Explosive detection machines can also be used for both carry-on and checked baggage and these detect volatile compounds given off from explosives using gas chromatography. A recent development is the use of backscatter X-rays to detect hidden weapons. These devices, which use Compton scattering, require that the stand close to a flat panel. Alternately, the passengers step fully shoed onto a device which scans in under 1.2 seconds for objects as small as a razor blade. In some countries, specially trained individuals may engage passengers in a conversation to detect rather than solely relying on equipment to find threats. A single backscatter scan exposes the target to between 0.05 and 0.1 microsievert of radiation, in comparison, the exposure from a standard chest x-ray is almost 100 times higher. Generally people are screened through airport security into areas where the gates to the aircraft are located. These areas are often called secure, sterile and airside, Airport food outlets have started using plastic glasses and utensils as opposed to glasses made out of glass and utensils made out of metal to reduce the usefulness of such items as weapons. In the United States non-passengers were once allowed on the concourses to meet arriving friends or relatives at their gates, non-passengers must obtain a gate pass to enter the secure area of the airport. The most common reasons that a non-passenger may obtain a pass is to assist children. In the United States, at least 24 hours notice is required for those planning to attend a business meeting inside the secure area of the airport. Other countries, such as Canada or Australia do not restrict non-travellers from accessing the airside area, sensitive areas in airports, including airport ramps and operational spaces, are restricted from the general public
Airport security
–
Baggage screening monitoring at
Bangkok Suvarnabhumi Airport
Airport security
–
A demonstrative image for "
Project Hostile Intent "
Airport security
–
TSA passenger screening
Airport security
–
A Dutch Marechaussee van
14.
Backscatter X-ray
–
Backscatter X-ray is an advanced X-ray imaging technology. Traditional X-ray machines detect hard and soft materials by the variation in x-ray intensity transmitted through the target, in contrast, backscatter X-ray detects the radiation that reflects from the target. It has potential applications where less-destructive examination is required, and can even if only one side of the target is available for examination. A competing technology is millimeter wave scanner, one can refer to an airport security machine of this type as a body scanner, whole body imager, security scanner or naked scanner. In the European Union, backscatter X-ray screening of passengers was banned in 2012 to protect passenger safety. Backscatter technology is based on the Compton scattering effect of X-rays, unlike a traditional X-ray machine, which relies on the transmission of X-rays through the object, backscatter X-ray detects the radiation that reflects from the object and forms an image. The backscatter pattern is dependent on the property and is good for imaging organic material. In contrast to millimeter wave scanners, which create a 3D image, for airport screening, images are taken from both sides of the human body. Backscatter X-ray was first applied in a commercial low-dose personnel scanning system by Dr. Steven W. Smith, Smith developed the Secure 1000 whole-body scanner in 1992 and then sold the device and associated patents to Rapiscan Systems, who now manufactures and distributes the device. American Science and Engineering Tek84 Engineering Group LLC, formerly Spectrum San Diego Inc, some backscatter X-ray scanners can scan much larger objects, such as trucks and containers. This scan is faster than a physical search and could potentially allow a larger percentage of shipping to be checked for smuggled items, weapons, drugs. It is being promoted as a means of examining the contents of vehicles, containers, other companies in the industry are Smiths Detection and Rapiscan. There are also gamma-ray-based systems coming to market, like the MVACIS, Backscatter x-ray technology has been proposed as an alternative to personal searches at airport and other security checkpoints easily penetrating clothing to reveal concealed weapons. It raises privacy concerns about what is seen by the person viewing the scan, some worry that viewing the image violates confidential medical information, such as the fact a passenger uses a colostomy bag, has a missing limb or wears a prosthesis, or is transgender. The ACLU and the Electronic Privacy Information Center are opposed to use of the technology. The ACLU refers to backscatter x-rays as a strip search. According to the Transportation Security Administration, in one trial 79 percent of the public opted to try backscatter over the traditional pat-down in secondary screening, according to the TSA, further distortion is used in the Phoenix airports trial system where photo-quality images are replaced by chalk outlines. The TSA has also commented that screening procedures such as having the screener viewing the image located far away from the person being screened could be a possibility
Backscatter X-ray
–
Backscatter technology produces an image that resembles a chalk etching.
Backscatter X-ray
–
Backscatter Unit
Backscatter X-ray
–
An image of Susan Hallowell, Director of the Transportation Security Administration's research lab taken with backscatter x-ray system.
15.
X-ray tube
–
An X-ray tube is a vacuum tube that converts electrical input power into X-rays. X-ray tubes evolved from experimental Crookes tubes with which X-rays were first discovered on November 8,1895, the availability of this controllable source of X-rays created the field of radiography, the imaging of partly opaque objects with penetrating radiation. In contrast to other sources of ionizing radiation, X-rays are only produced as long as the X-ray tube is energized, X-ray tubes are also used in CT scanners, airport luggage scanners, X-ray crystallography, material and structure analysis, and for industrial inspection. The anode is supported on bearings and can be rotated by electromagnetic induction from a series of stator windings outside the evacuated tube. Typically, eddy currents are induced in a metal cylinder. The superimposition of external magnetic induction and induction from the eddy currents, because the entire anode assembly has to be contained within the evacuated tube, heat removal is a serious problem, further exacerbated by the higher power rating available. Due to the heat generation, a matched thermal expansion of glass. For this, high-borate borosilicate glass pioneered by Otto Schott is often used, direct cooling by conduction or convection, as in the Coolidge tube, is difficult. In most tubes, the anode is suspended on ball bearings with silver powder lubrication which provide almost negligible cooling by conduction, a recent development has been liquid gallium lubricated fluid dynamic bearings which can withstand very high temperatures without contaminating the tube vacuum. The large bearing surface and metal lubricant provide an effective method for conduction of heat from the anode. The anode must be constructed of high temperature materials, the focal spot temperature can reach 2,500 °C during an exposure, and the anode assembly can reach 1,000 °C following a series of large exposures. Typical materials are a target on a molybdenum core, backed with graphite. The rhenium makes the tungsten more ductile and resistant to wear from the impact of the electron beams, the molybdenum conducts heat from the target. The graphite provides thermal storage for the anode, and minimizes the rotating mass of the anode, increasing demand for high-performance Computed tomography scanning and angiography systems has driven development of very high performance medical X-ray tubes. Contemporary CT tubes have power ratings of up to 100 kW and anode heat capacity of 6 MJ, some X-ray examinations need very high-resolution images and therefore require X-ray tubes that can generate very small focal spot sizes, typically below 50 µm in diameter. These tubes are called microfocus X-ray tubes, there are two basic types of microfocus X-ray tubes, solid-anode tubes and metal-jet-anode tubes. Many microfocus X-ray sources operate with focus spots in the range 5-20 µm, the major drawback of solid-anode microfocus X-ray tubes is the very low power they operate at. In order to avoid melting of the anode the electron-beam power density must be below a maximum value and this value is somewhere in the range 0. 4-0.8 W/µm depending on the anode material
X-ray tube
–
Coolidge X-ray tube, from around 1917. The heated cathode is on the left, and the anode is right. The X-rays are emitted downwards.
X-ray tube
–
A: Anode<
X-ray tube
–
typical rotating anode X-ray tube
X-ray tube
–
Spectrum of the X-rays emitted by an X-ray tube with a
rhodium target, operated at 60
kV. The smooth, continuous curve is due to
bremsstrahlung, and the spikes are
characteristic K lines for rhodium atoms.
16.
Photon
–
A photon is an elementary particle, the quantum of the electromagnetic field including electromagnetic radiation such as light, and the force carrier for the electromagnetic force. The photon has zero rest mass and is moving at the speed of light. Like all elementary particles, photons are currently best explained by quantum mechanics and exhibit wave–particle duality, exhibiting properties of both waves and particles. For example, a photon may be refracted by a lens and exhibit wave interference with itself. The quanta in a light wave cannot be spatially localized, some defined physical parameters of a photon are listed. The modern concept of the photon was developed gradually by Albert Einstein in the early 20th century to explain experimental observations that did not fit the classical model of light. The benefit of the model was that it accounted for the frequency dependence of lights energy. The photon model accounted for observations, including the properties of black-body radiation. In that model, light was described by Maxwells equations, in 1926 the optical physicist Frithiof Wolfers and the chemist Gilbert N. Lewis coined the name photon for these particles. After Arthur H. Compton won the Nobel Prize in 1927 for his studies, most scientists accepted that light quanta have an independent existence. In the Standard Model of particle physics, photons and other particles are described as a necessary consequence of physical laws having a certain symmetry at every point in spacetime. The intrinsic properties of particles, such as charge, mass and it has been applied to photochemistry, high-resolution microscopy, and measurements of molecular distances. Recently, photons have been studied as elements of quantum computers, in 1900, the German physicist Max Planck was studying black-body radiation and suggested that the energy carried by electromagnetic waves could only be released in packets of energy. In his 1901 article in Annalen der Physik he called these packets energy elements, the word quanta was used before 1900 to mean particles or amounts of different quantities, including electricity. In 1905, Albert Einstein suggested that waves could only exist as discrete wave-packets. He called such a wave-packet the light quantum, the name photon derives from the Greek word for light, φῶς. Arthur Compton used photon in 1928, referring to Gilbert N. Lewis, the name was suggested initially as a unit related to the illumination of the eye and the resulting sensation of light and was used later in a physiological context. Although Wolferss and Lewiss theories were contradicted by many experiments and never accepted, in physics, a photon is usually denoted by the symbol γ
Photon
–
Large Hadron Collider tunnel at
CERN
17.
Betatron
–
A betatron is a type of cyclic particle accelerator. It is essentially a transformer with a vacuum tube as its secondary coil. An alternating current in the primary coils accelerates electrons in the vacuum around a circular path, the betatron was the first machine capable of producing electron beams at energies higher than could be achieved with a simple electron gun. Subsequent development occurred in the United States through Donald Kerst in the 1940s, in other words, the magnetic field at the orbit must be half the average magnetic field over its circular cross section, ⇔ H0 =12 θ0 π r 02. This condition is often called Widerøes condition, the name betatron was chosen during a departmental contest. Betatrons were historically employed in particle physics experiments to provide high-energy beams of electrons—up to about 300 MeV. If the electron beam is directed at a plate, the betatron can be used as a source of energetic x-rays or gamma rays. The Radiation Center, the first private medical center to treat patients with a betatron, was opened by Dr. O. Arthur Stiennon in a suburb of Madison. The maximum energy that a betatron can impart is limited by the strength of the field due to the saturation of iron. The next generation of accelerators, the synchrotrons, overcame these limitations
Betatron
–
First betatron at University of Illinois. Kerst is at right, examining the vacuum chamber between the poles of the 4 ton magnet.
Betatron
–
A 6 MeV betatron (1942)
18.
Linear particle accelerator
–
The principles for such machines were proposed by Gustav Ising in 1924, while the first machine that worked was constructed by Rolf Widerøe in 1928 at the RWTH Aachen University. The design of a linac depends on the type of particle that is being accelerated, linacs range in size from a cathode ray tube to the 3. 2-kilometre-long linac at the SLAC National Accelerator Laboratory in Menlo Park, California. A linear particle accelerator consists of the elements, The particle source. The design of the source depends on the particle that is being moved, electrons are generated by a cold cathode, a hot cathode, a photocathode, or radio frequency ion sources. Protons are generated in an ion source, which can have different designs. If heavier particles are to be accelerated, an ion source is needed. A high voltage source for the injection of particles. The length will vary with the application, if the device is used for the production of X-rays for inspection or therapy the pipe may be only 0.5 to 1.5 meters long. If the device is to be an injector for a synchrotron it may be about ten meters long, if the device is used as the primary accelerator for nuclear particle investigations, it may be several thousand meters long. Within the chamber, electrically isolated cylindrical electrodes are placed, whose length varies with the distance along the pipe, likewise, because its mass is so small, electrons have much less kinetic energy than protons at the same speed. One or more sources of radio energy, used to energize the cylindrical electrodes. A very high power accelerator will use one source for each electrode, the sources must operate at precise power, frequency and phase appropriate to the particle type to be accelerated to obtain maximum device power. If electrons are accelerated to produce X-rays then a water cooled tungsten target is used, various target materials are used when protons or other nuclei are accelerated, depending upon the specific investigation. For particle-to-particle collision investigations the beam may be directed to a pair of storage rings, the beams may then be extracted from the storage rings to create head on particle collisions. This accelerates the particle, imparting energy to it in the form of increased velocity, at speeds near the speed of light, the incremental velocity increase will be small, with the energy appearing as an increase in the mass of the particles. In portions of the accelerator where this occurs, the tubular electrode lengths will be almost constant, additional magnetic or electrostatic lens elements may be included to ensure that the beam remains in the center of the pipe and its electrodes. Very long accelerators may maintain an alignment of their components through the use of servo systems guided by a laser beam. The high density of the output makes the linac particularly attractive for use in loading storage ring facilities with particles in preparation for particle to particle collisions
Linear particle accelerator
–
The linac within the
Australian Synchrotron uses
radio waves from a series of
RF cavities at the start of the linac to accelerate the electron beam in bunches to energies of 100 MeV.
Linear particle accelerator
–
Quadrupole magnets surrounding the linac of the
Australian Synchrotron are used to help
focus the electron beam
Linear particle accelerator
–
The
Stanford University superconducting linear accelerator, housed on campus below the Hansen Labs until 2007. This facility is separate from
SLAC
Linear particle accelerator
–
Steel casting undergoing x-ray using the linear accelerator at
Goodwin Steel Castings Ltd
19.
Synchrotron
–
A synchrotron is a particular type of cyclic particle accelerator, descended from the cyclotron, in which the accelerating particle beam travels around a fixed closed-loop path. The magnetic field which bends the particle beam into its closed path increases with time during the accelerating process, the most powerful modern particle accelerators use versions of the synchrotron design. The largest synchrotron-type accelerator is the 27-kilometre-circumference Large Hadron Collider near Geneva, Switzerland, the synchrotron principle was invented by Vladimir Veksler in 1944. Edwin McMillan constructed the first electron synchrotron in 1945, arriving at the idea independently, the first proton synchrotron was designed by Sir Marcus Oliphant and built in 1952. Several specialized types of machines are used today, A storage ring is a special type of synchrotron in which the kinetic energy of the particles is kept constant. A synchrotron light source is a combination of different electron accelerator types and this radiation is then used in experimental stations located on different beamlines. In addition to the ring, a synchrotron light source usually contains a linear accelerator. The linac and the booster are used to accelerate the electrons to their final energy before they are magnetically kicked into the storage ring. Synchrotron light sources in their entirety are sometimes called synchrotrons, although this is technically incorrect, a cyclic collider is also a combination of different accelerator types, including two intersecting storage rings and the respective pre-accelerators. The synchrotron evolved from the cyclotron, the first cyclic particle accelerator, in a synchrotron, this adaptation is done by variation of the magnetic field strength in time, rather than in space. For particles that are not close to the speed of light, by increasing these parameters accordingly as the particles gain energy, their circulation path can be held constant as they are accelerated. This allows the chamber for the particles to be a large thin torus, rather than a disk as in previous. Also, the profile of the vacuum chamber allowed for a more efficient use of magnetic fields than in a cyclotron. Some important components are given by radio frequency cavities for direct acceleration, dipole magnets for deflection of particles, the maximum energy that a cyclic accelerator can impart is typically limited by the maximum strength of the magnetic fields and the minimum radius of the particle path. Thus one method for increasing the limit is to use superconducting magnets. Electron/positron accelerators may also be limited by the emission of synchrotron radiation, the limiting beam energy is reached when the energy lost to the lateral acceleration required to maintain the beam path in a circle equals the energy added each cycle. More powerful accelerators are built by using large radius paths and by using more numerous, lighter particles lose a larger fraction of their energy when deflected. Practically speaking, the energy of electron/positron accelerators is limited by this radiation loss, the energy of such accelerators is limited strictly by the strength of magnets and by the cost
Synchrotron
–
Schematic of a synchrotron
Synchrotron
–
The first synchrotron to use the "racetrack" design with straight sections, a 300 MeV electron synchrotron at
University of Michigan in 1949, designed by
Dick Crane.
Synchrotron
–
The interior of the
Australian Synchrotron facility, a
synchrotron light source. Dominating the image is the
storage ring, showing a
beamline at front right. The storage ring's interior includes a synchrotron and a
linac.
Synchrotron
–
Modern industrial-scale synchrotrons can be very large (here,
Soleil near
Paris)
20.
Gamma ray
–
Gamma ray, denoted by the lower-case Greek letter gamma, is penetrating electromagnetic radiation of a kind arising from the radioactive decay of atomic nuclei. It consists of photons in the highest observed range of photon energy, paul Villard, a French chemist and physicist, discovered gamma radiation in 1900 while studying radiation emitted by radium. In 1903, Ernest Rutherford named this radiation gamma rays, Rutherford had previously discovered two other types of radioactive decay, which he named alpha and beta rays. Gamma rays are able to ionize atoms, and are thus biologically hazardous. The decay of a nucleus from a high energy state to a lower energy state. Natural sources of gamma rays on Earth are observed in the decay of radionuclides. There are rare terrestrial natural sources, such as lightning strikes and terrestrial gamma-ray flashes, However, a large fraction of such astronomical gamma rays are screened by Earths atmosphere and can only be detected by spacecraft. Gamma rays typically have frequencies above 10 exahertz, and therefore have energies above 100 keV and wavelengths less than 10 picometers, However, this is not a strict definition, but rather only a rule-of-thumb description for natural processes. Electromagnetic radiation from radioactive decay of nuclei is referred to as gamma rays no matter its energy. This radiation commonly has energy of a few hundred keV, in astronomy, gamma rays are defined by their energy, and no production process needs to be specified. The energies of gamma rays from astronomical sources range to over 10 TeV, a notable example is the extremely powerful bursts of high-energy radiation referred to as long duration gamma-ray bursts, of energies higher than can be produced by radioactive decay. These bursts of gamma rays are thought to be due to the collapse of stars called hypernovae, the first gamma ray source to be discovered historically was the radioactive decay process called gamma decay. In this type of decay, a nucleus emits a gamma ray almost immediately upon formation. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900, However, Villard did not consider naming them as a different fundamental type. Rutherford also noted that gamma rays were not deflected by a field, another property making them unlike alpha. Gamma rays were first thought to be particles with mass, like alpha, Rutherford initially believed that they might be extremely fast beta particles, but their failure to be deflected by a magnetic field indicated that they had no charge. In 1914, gamma rays were observed to be reflected from crystal surfaces, Rutherford and his coworker Edward Andrade measured the wavelengths of gamma rays from radium, and found that they were similar to X-rays, but with shorter wavelengths and higher frequency. This was eventually recognized as giving them more energy per photon
Gamma ray
–
Gamma rays are emitted during
nuclear fission in nuclear explosions.
Gamma ray
–
Illustration of an emission of a gamma ray (γ) from an atomic nucleus
Gamma ray
Gamma ray
–
A
hypernova. Artist's illustration showing the life of a
massive star as
nuclear fusion converts lighter elements into heavier ones. When fusion no longer generates enough pressure to counteract gravity, the star rapidly collapses to form a
black hole. Theoretically, energy may be released during the collapse along the axis of rotation to form a long duration
gamma-ray burst.
21.
Radioactive
–
A material containing such unstable nuclei is considered radioactive. Certain highly excited short-lived nuclear states can decay through neutron emission, or more rarely, however, for a collection of atoms, the collections expected decay rate is characterized in terms of their measured decay constants or half-lives. This is the basis of radiometric dating, the half-lives of radioactive atoms have no known upper limit, spanning a time range of over 55 orders of magnitude, from nearly instantaneous to far longer than the age of the universe. A radioactive nucleus with spin can have no defined orientation. If there are multiple particles produced during a single decay, as in decay, their relative angular distribution. Such a parent process could be a previous decay, or a nuclear reaction, the decaying nucleus is called the parent radionuclide, and the process produces at least one daughter nuclide. Except for gamma decay or internal conversion from an excited state. When the number of changes, an atom of a different chemical element is created. The first decay processes to be discovered were alpha decay, beta decay, alpha decay occurs when the nucleus ejects an alpha particle. This is the most common process of emitting nucleons, but highly excited nuclei can eject single nucleons, or in the case of cluster decay, specific light nuclei of other elements. Beta decay occurs when the nucleus emits an electron or positron, the nucleus may capture an orbiting electron, causing a proton to convert into a neutron in a process called electron capture. All of these result in a well-defined nuclear transmutation. By contrast, there are radioactive decay processes that do not result in a nuclear transmutation, another type of radioactive decay results in products that vary, appearing as two or more fragments of the original nucleus with a range of possible masses. For a summary table showing the number of stable and radioactive nuclides in each category, there are 29 naturally occurring chemical elements on Earth that are radioactive. They are those that contain 34 radionuclides that date before the time of formation of the solar system, well-known examples are uranium and thorium, but also included are naturally occurring long-lived radioisotopes, such as potassium-40. Radioactivity was discovered in 1896 by the French scientist Henri Becquerel and these materials glow in the dark after exposure to light, and he suspected that the glow produced in cathode ray tubes by X-rays might be associated with phosphorescence. He wrapped a photographic plate in black paper and placed various phosphorescent salts on it, all results were negative until he used uranium salts. The uranium salts caused a blackening of the plate in spite of the plate being wrapped in black paper and these radiations were given the name Becquerel Rays
Radioactive
–
Pierre and Marie Curie in their Paris laboratory, before 1907
Radioactive
–
Alpha decay is one type of radioactive decay, in which an atomic nucleus emits an
alpha particle, and thereby transforms (or "decays") into an atom with a
mass number decreased by 4 and
atomic number decreased by 2.
Radioactive
–
Taking an X-ray image with early
Crookes tube apparatus in 1896. The Crookes tube is visible in the centre. The standing man is viewing his hand with a
fluoroscope screen; this was a common way of setting up the tube. No precautions against radiation exposure are being taken; its hazards were not known at the time.
Radioactive
–
Gamma-ray energy spectrum of uranium ore (inset). Gamma-rays are emitted by decaying
nuclides, and the gamma-ray energy can be used to characterize the decay (which nuclide is decaying to which). Here, using the gamma-ray spectrum, several nuclides that are typical of the decay chain of 238 U have been identified: 226 Ra, 214 Pb, 214 Bi.
22.
Cobalt-60
–
Cobalt-60, 60Co, is a synthetic radioactive isotope of cobalt with a half-life of 5.2714 years. It is produced artificially in nuclear reactors, deliberate industrial production depends on neutron activation of bulk samples of the monoisotopic and mononuclidic cobalt isotope 59Co. Measurable quantities are produced as a by-product of typical nuclear power plant operation. In the latter case the incidentally produced 60Co is largely the result of stages of neutron activation of iron isotopes in the reactors steel structures via the creation of 59Co precursor. The simplest case of the latter would result from the activation of 58Fe, 60Co decays by beta decay to the stable isotope nickel-60. Corresponding to its half-life the radioactive activity of one gram of 60Co is 44 TBq, the absorbed dose constant is related to the decay energy and time. For 60Co it is equal to 0.35 mSv/ at one meter from the source and this allows calculation of the equivalent dose, which depends on distance and activity. Example, a 60Co source with an activity of 2.8 GBq, the swallowing of 60Co reduces the distance to a few millimeters, and the same dose is achieved within seconds. Test sources, such as used for school experiments, have an activity of <100 kBq. Devices for nondestructive material testing use sources with activities of 1 TBq, the high γ-energies result in a significant mass difference between 60Ni and 60Co of 0.003 u. This amounts to nearly 20 watts per gram, nearly 30 times larger than that of 238Pu, the diagram shows a decay scheme of 60Co and 60mCo. The main β-decay transitions are shown, the probability for population of the middle energy level of 2.1 MeV by β-decay is 0. 0022%, with a maximum energy of 665.26 keV. Energy transfers between the three levels generate six different gamma-ray frequencies, in the diagram the two important ones are marked. Internal conversion energies are well below the energy levels. 60mCo is an isomer of 60Co with a half-life of 10.467 minutes. It decays by internal transition to 60Co, emitting 58.6 keV gamma rays, the main advantage of 60Co is that it is a high intensity gamma-ray emitter with a relatively long half-life,5.27 years, compared to other gamma ray sources of similar intensity. The β-decay energy is low and easily shielded, however, the emission lines have energies around 1.3 MeV. The main uses for 60Co are, As a tracer for cobalt in chemical reactions Sterilization of medical equipment, Cobalt therapy, using beams of gamma rays from 60Co teletherapy machines to treat cancer, has been widely used since the 1950s
Cobalt-60
–
A container containing cobalt-60.
Cobalt-60
–
γ-ray spectrum of cobalt-60
Cobalt-60
–
Security screening of cars at the Superbowl using 60 Co gamma-ray scanner
Cobalt-60
–
60 Co
teletherapy machine for cancer radiotherapy, early 1950s.
23.
Caesium-137
–
Caesium-137 has a half-life of about 30.17 years. About 95 percent decays by emission to a metastable nuclear isomer of barium. The remainder directly populates the ground state of barium-137, which is stable, Ba-137m has a half-life of about 153 seconds, and is responsible for all of the emissions of gamma rays in samples of caesium-137. One gram of caesium-137 has an activity of 3.215 terabecquerel, the main photon peak of Ba-137m is 662 keV. Caesium-137 has a number of practical uses, in small amounts, it is used to calibrate radiation-detection equipment. In medicine, it is used in radiation therapy, in industry, it is used in flow meters, thickness gauges, moisture-density gauges, and in gamma ray well logging devices. Caesium-137 is not widely used for industrial radiography because it is chemically reactive. The salts of caesium are also soluble in water, and this complicates the safe handling of caesium, cobalt-60,60 27Co, is preferred for radiography, since it is chemically a rather nonreactive metal and produces higher energy gamma-ray photons. As a man-made isotope, caesium-137 has been used to date wine and detect counterfeits, caesium-137 reacts with water, producing a water-soluble compound. The biological behavior of caesium is similar to that of potassium and rubidium, after entering the body, caesium gets more or less uniformly distributed throughout the body, with the highest concentrations in soft tissue. The biological half-life of caesium is rather short, at about 70 days. A1972 experiment showed that dogs are subjected to a whole body burden of 3800 μCi/kg of caesium-137, they die within 33 days. Accidental ingestion of caesium-137 can be treated with Prussian blue, which binds to it chemically, as of 2005 and for the next few hundred years, caesium-137 is the principal source of radiation in the zone of alienation around the Chernobyl nuclear power plant. Together with caesium-134, iodine-131, and strontium-90, caesium-137 was among the isotopes distributed by the explosion that constitute the greatest risk to health. The mean contamination of caesium-137 in Germany following the Chernobyl disaster was 2000 to 4000 Bq/m2 and this corresponds to a contamination of 1 mg/km2 of caesium-137, totaling about 500 grams deposited over all of Germany. In Scandinavia, some reindeer and sheep exceeded the Norwegian legal limit 26 years after Chernobyl, as of 2016 the Chernobyl caesium-137 has decayed by half, but can have been locally concentrated by much larger factors. In April 2011, elevated levels of caesium-137 were also being found in the environment after the Fukushima Daiichi nuclear disasters in Japan. In March 2013, a fish caught near the plant had a record 740,000 becquerels per kilogram of radioactive caesium, above the 100 becquerels per kilogram government limit
Caesium-137
–
Cs-137 Decay Scheme
24.
Photographic plate
–
Photographic plates preceded photographic film as a capture medium in photography. The light-sensitive emulsion of silver salts was coated on a plate, typically thinner than common window glass. Glass plates were far superior to film for research-quality imaging because they were stable and less likely to bend or distort. Early plates used the wet collodion process, the wet plate process was replaced late in the 19th century by gelatin dry plates. Glass plate photographic material largely faded from the market in the early years of the 20th century, as more convenient. Workshops on the use of glass plate photography as a medium or for artistic use are still being conducted. A number of observatories, including Harvard College and Sonneberg, maintain large archives of photographic plates, many solar system objects were discovered by using photographic plates, superseding earlier visual methods. Discovery of minor planets using photographic plates was pioneered by Max Wolf beginning with his discovery of 323 Brucia in 1891, the first natural satellite discovered using photographic plates was Phoebe in 1898. Glass-backed plates, rather than film, were used in astronomy because they do not shrink or deform noticeably in the development process or under environmental changes. Photographic plates were also an important tool in early high-energy physics, Photographic emulsions were originally coated on thin glass plates for imaging with electron microscopes, which provided a more rigid, stable and flatter plane compared to plastic films. Beginning in the 1970s, high-contrast, fine grain emulsions coated on thicker plastic films manufactured by Kodak, Ilford and these films have largely been replaced by digitally imaging technologies. The earliest flexible films of the late 1880s were sold for use in medium-format cameras. The plastic was not of high optical quality and tended to curl. Initially, a transparent plastic base was more expensive to produce than glass, quality was eventually improved, manufacturing costs came down, and most amateurs gladly abandoned plates for films. After large-format high quality cut films for professional photographers were introduced in the late 1910s, CCD cameras have several advantages over glass plates, including high efficiency, linear light response, and simplified image acquisition and processing. The manufacture of plates has been discontinued by Kodak, Agfa. In the realm of traditional photography, a number of historical process enthusiasts make their own wet or dry plates from raw materials. Several institutions have established archives to preserve photographic plates and prevent their valuable historical information from being lost, the emulsion on the plate can deteriorate
Photographic plate
–
AGFA photographic plates, 1880
Photographic plate
–
Mimosa Panchroma-Studio-Antihalo Panchromatic glass plates, 9 x 12cm, Mimosa A.-G. Dresden
Photographic plate
–
Negative plate
25.
Digitizing
–
Digitizing or digitization is the representation of an object, image, sound, document or signal by generating a series of numbers that describe a discrete set of its points or samples. The result is called digital representation or, more specifically, an image, for the object. Unlike analog data, which typically suffers some loss of quality each time it is copied or transmitted, digital data can, in theory and this is why it is a favored way of preserving information for many organisations around the world. The term digitization is often used when diverse forms of information, such as text, sound, Digital information exists as one of two digits, either 0 or 1. These are known as bits and the sequences of 0s and 1s that constitute information are called bytes. Analog signals are continuously variable, both in the number of values of the signal at a given time, as well as in the number of points in the signal in a given period of time. Digitization occurs in two parts, Discretization The reading of an analog signal A, and, at time intervals. Each such reading is called a sample and may be considered to have infinite precision at this stage, Quantization Samples are rounded to a set of numbers. In general, these can occur at the time, though they are conceptually distinct. A series of integers can be transformed into an analog output that approximates the original analog signal. Such a transformation is called a DA conversion, the sampling rate and the number of bits used to represent the integers combine to determine how close such an approximation to the analog signal a digitization will be. The term is used to describe the scanning of analog sources into computers for editing. In this last case, as in normal photos, sampling rate refers to the resolution of the image, Digitization is also used to describe the process of populating databases with files or data. Digitizing may also used in the field of apparel, where an image may be recreated with the help of embroidery digitizing software tools and this machine code is fed into an embroidery machine and applied to the fabric. The most supported format is DST file, apparel companies also digitize clothing patterns Analog signals are continuous electrical signals, digital signals are non-continuous. Analog signal can be converted to digital signal by ADC, nearly all recorded music has been digitized. About 12 percent of the 500, 000+ movies listed on the Internet Movie Database are digitized on DVD, handling of analog signal becomes easy when it is digitized because the signal is digitized before modulation and transmission. The conversion process of analog to digital consists of two processes, sampling and quantizing, Digitization of personal multimedia such as home movies, slides, and photographs is a popular method of preserving and sharing older repositories
Digitizing
–
Internet Archive book
scanner
Digitizing
–
Digitization at the
British Library of a
Dunhuang manuscript for the
International Dunhuang Project
26.
Flat panel detector
–
Flat panel detectors are a class of solid-state x-ray digital radiography devices similar in principle to the image sensors used in digital photography and video. X-rays pass through the subject being imaged and strike one of two types of detectors, indirect detectors contain a layer of scintillator material, either gadolinium oxysulfide or cesium iodide, which converts the x-rays into light. Due to the impracticability of focusing x-rays, the sensors have exactly the size as the image they capture. Directly behind the scintillator layer is an amorphous silicon-on glass detector array manufactured using a very similar to that used to make LCD televisions. Like a TFT-LCD display, millions of roughly 0.2 mm pixels each containing a thin-film transistor form a grid patterned in amorphous silicon on the glass substrate, direct FPDs Amorphous selenium FPDs are known as “direct” detectors because X-ray photons are converted directly into charge. The outer layer of the panel in this design is typically a high-voltage bias electrode. X-ray photons create electron-hole pairs in a-Se, and the transit of these electrons, the charge pattern is then read by a TFT array in the same way images produced by indirect detectors are read. Flat-panel detectors are sensitive and faster than film. Their sensitivity allows a lower dose of radiation for a picture quality than film. They are lighter, far more durable, smaller in volume, more accurate, real time capture with flat panel detector
Flat panel detector
–
A portable @Si flat panel detector is used to visualise the mouvement of liquids in sand cores under high pressure.
Flat panel detector
–
Flat panel detector used in
digital radiography
27.
Ionization chamber
–
Ion chambers have a good uniform response to radiation over a wide range of energies and are the preferred means of measuring high levels of gamma radiation. They are widely used in the power industry, research labs, radiography, radiobiology. An ionization chamber measures the charge from the number of ion pairs created within a gas caused by incident radiation and it consists of a gas-filled chamber with two electrodes, known as anode and cathode. The electrodes may be in the form of plates, or a cylinder arrangement with a coaxially located internal anode wire. A voltage potential is applied between the electrodes to create a field in the fill gas. This generates a current which is measured by an electrometer circuit. The electrometer must be capable of measuring the small output current which is in the region of femtoamperes to picoamperes, depending on the chamber design, radiation dose. This continual generation of charge produces a current, which is a measure of the total ionizing dose entering the chamber. However, the chamber cannot discriminate between radiation types and cannot produce a spectrum of radiation. This is in distinction to the Geiger-Müller tube or the proportional counter whereby secondary electrons, the following chamber types are commonly used. This is a chamber open to atmosphere, where the fill gas is ambient air. The domestic smoke detector is an example of this, where a natural flow of air through the chamber is necessary so that smoke particles can be detected by the change in ion current. Other examples are applications where the ions are created outside the chamber but are carried in by a flow of air or gas. These chambers are normally cylindrical and operate at atmospheric pressure, and this is to stop moisture building up in the interior of the chamber, which would otherwise be introduced by the pump effect of changing atmospheric air pressure. These chambers have a body made of aluminium or plastic a few millimetres thick. The material is selected to have a number similar to that of air so that the wall is said to be air equivalent over a range of radiation beam energies. The higher the number of the wall material, the greater the chance of interaction. The wall thickness is a trade-off between maintaining the air effect with a wall, and increasing sensitivity by using a thinner wall
Ionization chamber
–
Ionization chamber made by Pierre Curie, c 1895-1900
Ionization chamber
–
Schematic diagram of parallel plate ion chamber, showing drift of ions. Electrons typically drift 1000 times faster than positive ions due to their much smaller mass.
Ionization chamber
–
Hand-held integral ion chamber survey meter in use
Ionization chamber
–
View of sliding beta shield on integral hand held instrument
28.
Geiger counter
–
It detects ionizing radiation such as alpha particles, beta particles and gamma rays using the ionization effect produced in a Geiger–Müller tube, which gives its name to the instrument. In wide and prominent use as a radiation survey instrument. Since then it has very popular due to its robust sensing element. However, there are limitations in measuring high radiation rates and the energy of incident radiation, a Geiger counter consists of a Geiger-Müller tube, the sensing element which detects the radiation, and the processing electronics, which displays the result. The Geiger-Müller tube is filled with a gas such as helium, neon, or argon at low pressure. The tube briefly conducts electrical charge when a particle or photon of incident radiation makes the gas conductive by ionization, the ionization is considerably amplified within the tube by the Townsend discharge effect to produce an easily measured detection pulse, which is fed to the processing and display electronics. This large pulse from the tube makes the G-M counter relatively cheap to manufacture, the electronics also generates the high voltage, typically 400–600 volts, that has to be applied to the Geiger-Müller tube to enable its operation. There are two types of radiation readout, counts or radiation dose, the counts display is the simplest and is the number of ionizing events displayed either as a count rate, commonly counts per second, or as a total over a set time period. The counts readout is normally used when alpha or beta particles are being detected, more complex to achieve is a display of radiation dose rate, displayed in a unit such as the sievert which is normally used for measuring gamma or X-ray dose rates. A G-M tube can detect the presence of radiation, but not its energy influences the radiations ionising effect. Consequently, instruments measuring dose rate require the use of an energy compensated G-M tube, the electronics will apply known factors to make this conversion, which is specific to each instrument and is determined by design and calibration. The readout can be analog or digital, and increasingly, modern instruments are offering serial communications with a host computer or network, there is usually an option to produce audible clicks representing the number of ionization events detected. This is the distinctive sound associated with hand held or portable Geiger counters. The purpose of this is to allow the user to concentrate on manipulation of the instrument whilst retaining auditory feedback on the radiation rate, there are two main limitations of the Geiger counter. Because the output pulse from a Geiger-Müller tube is always the same regardless of the energy of the incident radiation. A further limitation is the inability to measure radiation rates due to the dead time of the tube. This is a period after each ionization of the gas during which any further incident radiation will not result in a count. Typically the dead time will reduce indicated count rates above about 104 to 105 counts per second depending on the characteristic of the tube being used, whilst some counters have circuitry which can compensate for this, for accurate measurements ion chamber instruments are preferred for high radiation rates
Geiger counter
–
A "two-piece" bench type Geiger–Müller counter with end-window detector.
Geiger counter
–
Laboratory use of a G-M counter with end window probe to measure beta radiation from a radioactive source
Geiger counter
–
Pancake G-M tube used for alpha and beta detection; the delicate mica window is usually protected by a mesh when fitted in an instrument.
Geiger counter
–
Early Geiger-Muller tube made in 1932 by Hans Geiger for laboratory use
29.
Dosimeter
–
A radiation dosimeter is a device that measures exposure to ionizing radiation. It has two uses, for human radiation protection and for measurement of dose in both medical and industrial processes. Ionising radiation damage to the body is cumulative, and is related to the total dose received. Such devices are known as legal if they have been approved for use in recording personnel dose for regulatory purposes. These are especially useful in high dose areas where residence time of the wearer is limited due to dose constraints, the dosimeter can be reset, usually after taking a reading for record purposes, and thereby re-used multiple times. MOSFET dosimeters are now used as clinical dosimeters for radiotherapy radiation beams, the main advantages of MOSFET devices are,1. The MOSFET dosimeter is direct reading with a thin active area. The physical size of the MOSFET when packaged is less than 4 mm.3, the post radiation signal is permanently stored and is dose rate independent. Gate oxide of MOSFET which is conventionally silicon dioxide is an active sensing material in MOSFET dosimeters, radiation creates defects in oxide, which in turn affects the threshold voltage of the MOSFET. This change in voltage is proportional to radiation dose. Alternate high-k gate dielectrics like Hafnium dioxide and Aluminum oxides are also proposed as a radiation dosimeters, film badge dosimeters are for one-time use only. The level of absorption is indicated by a change to the film emulsion. Quartz fiber dosimeters are charged to a high voltage, as the gas in the dosimeter chamber becomes ionized by radiation the charge leaks away, causing the fiber indicator to change against a graduated scale. A thermoluminescent dosimeter measures ionizing radiation exposure by measuring the intensity of light emitted from a crystal in the detector when heated. The intensity of light emitted is dependent upon the radiation exposure, both the quartz fiber and film badge types are being superseded by the TLD and the EPD. This is shown in the accompanying diagram and these quantities cannot be practically measured and are a calculated value of irradiation of organs of the human body, which is arrived at by using an anthropomorphic phantom. This is a 3D computational model of the body which attempts to take into account a number of complex effects such as body self-shielding. As protection quantities cannot practically be measured, operational quantities are used to them to practical radiation instrument
Dosimeter
–
Electronic personal dosimeter (EPD, Soeks 01M in particular). These give a dose rate, accumulated dose reading and usually have alarm functions.
Dosimeter
–
QFD - These are now largely superseded
Dosimeter
–
View of QFD reading
Dosimeter
–
Russian Sosna radiometer-dosimeter (Rear view)
30.
Absorbed dose
–
Absorbed dose is a physical dose quantity D representing the mean energy imparted to matter per unit mass by ionizing radiation. In the SI system of units, the unit of measure is joules per kilogram, the non-SI CGS unit rad is sometimes also used, predominantly in the USA. Absorbed dose is used in the calculation of dose uptake in living tissue in both radiation protection and radiology and it is also used to directly compare the effect of radiation on inanimate matter. The quantity absorbed dose is of importance in radiological protection for calculating radiation dose. However, absorbed dose is a quantity and used unmodified is not an adequate indicator of the likely health effects in humans. It has been found that for stochastic radiation risk consideration must be given to the type of radiation and the sensitivity of the irradiated tissues, which requires the use of modifying factors. Conventionally therefore, unmodified absorbed dose is not used for comparing stochastic risks, to represent stochastic risk the equivalent dose H T and effective dose E are used, and appropriate dose factors and coefficients are used to calculate these from the absorbed dose. Equivalent and effective dose quantities are expressed in units of the sievert or rem which implies that biological effects have been taken into account and these are usually in accordance with the recommendations of the International Committee on Radiation Protection and International Commission on Radiation Units and Measurements. The coherent system of protection quantities developed by them is shown in the accompanying diagram. Absorbed dose is used to rate the survivability of devices such as components in ionizing radiation environments. Absorbed dose is the physical quantity used to ensure irradiated food has received the correct dose to ensure effectiveness. Variable doses are used depending on the application and can be as high as 70 kGy, the absorbed dose is equal to the radiation exposure of the radiation beam multiplied by the ionization energy of the medium to be ionized. For example, the energy of dry air at 20 °C and 101.325 kPa of pressure is 33. 97±0.06 J/C. Therefore, an exposure of 2. 58×10−4 C/kg would deposit an absorbed dose of 8. 76×10−3 J/kg in dry air at those conditions, self-shielding means that the absorbed dose will be higher in the tissues facing the source than deeper in the body. The mass average can be important in evaluating the risks of radiotherapy treatments, since they are designed to very specific volumes in the body. For example, if 10% of a bone marrow mass is irradiated with 10 Gy of radiation locally. Bone marrow makes up 4% of the mass, so the whole-body absorbed dose would be 0.04 Gy. The first figure is indicative of the effects on the tumour, while the second
Absorbed dose
–
External dose quantities used in radiation protection and dosimetry
31.
Radiation protection
–
The IAEA also states The accepted understanding of the term radiation protection is restricted to protection of people. Suggestions to extend the definition to include the protection of species or the protection of the environment are controversial. Ionizing radiation is used in industry and medicine, and can present a significant health hazard. It causes microscopic damage to living tissue, which can result in burns and radiation sickness at high exposures. Fundamental to radiation protection is the reduction of expected dose and the measurement of dose uptake. The ICRP recommends, develops and maintains the International System of Radiological Protection based on evaluation of the body of scientific studies available, the recommendations it makes flow down to national regulators, which have the opportunity to incorporate them into law. This is shown in the accompanying diagram, the types of exposure, as well as government regulations and legal exposure limits are different for each of these groups, so they must be considered separately. There are three factors that control the amount, or dose, of radiation received from a source, Radiation exposure can be managed by a combination of these factors, Time, Reducing the time of an exposure reduces the effective dose proportionally. An example of reducing radiation doses by reducing the time of exposures might be improving operator training to reduce the time they take to handle a source, distance, Increasing distance reduces dose due to the inverse square law. Distance can be as simple as handling a source with forceps rather than fingers, Shielding, The term biological shield refers to a mass of absorbing material placed around a reactor, or other radioactive source, to reduce the radiation to a level safe for humans. Hence, shielding strength or thickness is measured in units of g/cm2. The radiation that manages to get through falls exponentially with the thickness of the shield, in x-ray facilities, walls surrounding the room with the x-ray generator may contain lead sheets, or the plaster may contain barium sulfate. Operators view the target through a glass screen, or if they must remain in the same room as the target. Almost any material can act as a shield from gamma or x-rays if used in sufficient amounts, practical radiation protection tends to be a job of juggling the three factors to identify the most cost effective solution. These use the overall principles, Justification, No unnecessary use of radiation is permitted. Limitation, Each individual must be protected against risks that are far too large through individual radiation dose limits, optimization, Radiation doses should all be kept as low as reasonably achievable. This means that it is not enough to remain under the radiation dose limits, as permit holder, you are responsible for ensuring that radiation doses are as low as reasonably achievable, which means that the actual radiation doses are often much lower than the permitted limit. ALARP is an acronym for an important principle in exposure to radiation and other health risks
Radiation protection
–
A
lead castle built to shield a radioactive sample in a lab
Radiation protection
–
International policy relationships in radiological protection
Radiation protection
–
Hand-held ion chamber survey meter in use
Radiation protection
–
Taking an X-ray image with early
Crookes tube apparatus in 1896. The Crookes tube is visible in the centre. The standing man is viewing his hand with a
fluoroscope screen. This was a common method of setting up the tube power. No precautions against radiation exposure are being taken; its hazards were not known at the time.
32.
X-ray image intensifier
–
An x-ray image intensifier is an image intensifier that converts x-rays into visible light at higher intensity than mere fluorescent screens do. Such intensifiers are used in imaging systems to allow low-intensity x-rays to be converted to a conveniently bright visible light output. The device contains a low absorbency/scatter input window, typically aluminum, input fluorescent screen, photocathode, electron optics, output fluorescent screen and these parts are all mounted in a high vacuum environment within glass or more recently, metal/ceramic. By its intensifying effect, It allows the viewer to easily see the structure of the object being imaged than fluorescent screens alone. The X-ray II requires lower absorbed doses due to more efficient conversion of x-ray quanta to visible light and this device was originally introduced in 1948. The overall function of an image intensifier is to convert incident x-ray photons to light photons of sufficient intensity to provide a viewable image, the first is conversion of x-ray photons to light photons by the input phosphor. CsI, Na is typically used due to its conversion efficiency thanks to high atomic number. The light photons are converted to electrons by a photocathode. A potential difference created between the anode and photocathode then accelerates these photoelectrons while electron lenses focus the beam down to the size of the output window, the output window is typically made of silver-activated zinc-cadmium sulfide and converts incident electrons back to visible light photons. At the input and output phosphors the number of photons is multiplied by several thousands and this gain makes image intensifiers highly sensitive to x-rays such that relatively low doses can be used for fluoroscopic procedures. X-ray image intensifiers became available in the early 1950s and were viewed through a microscope, viewing of the output was via mirrors and optical systems until the adaption of television systems in the 1960s. The input screens range from 15–57 cm, with the 23 cm,33 cm and 40 cm being among the most common. Within each image intensifier, the field size can be changed using the voltages applied to the internal electron optics to achieve magnification. For example, the 23 cm commonly used in applications can be set to a format of 23,17. Because the output screen remains fixed in size, the output appears to magnify the input image, high-speed digitalisation with analogue video signal came about in the mid-1970s, with pulsed fluoroscopy developed in the mid-1980s harnessing low dose rapid switching x-ray tubes. In the late 1990s image intensifiers began being replaced with flat panel detectors on fluoroscopy machines giving competition to the image intensifiers, C-arm mobile fluoroscopy machines are often colloquially referred to as image intensifiers, however strictly speaking the image intensifier is only one part of the machine. Fluoroscopy, using a machine with an image intensifier, has applications in many areas of medicine. Fluoroscopy allows live images to be viewed so that image-guided surgery is feasible, common uses include orthopedics, gastroenterology and cardiology
X-ray image intensifier
–
Fixed X-ray image intensifier
X-ray image intensifier
–
C-arm of a mobile X-ray image intensifier
33.
Caesium iodide
–
Caesium iodide is the ionic compound of caesium and iodine. It is often used as the input phosphor of an image intensifier tube found in fluoroscopy equipment. Caesium iodide photocathodes are highly efficient at extreme ultraviolet wavelengths, an important application of caesium iodide crystals, which are scintillators, is electromagnetic calorimetry in experimental particle physics. Pure CsI is a fast and dense scintillating material with high light yield. It shows two main components, one in the near ultraviolet region at the wavelength of 310 nm. The drawbacks of CsI are a temperature gradient and a slight hygroscopicity. Caesium iodide is used as a beamsplitter in Fourier transform infrared spectrometers and it has a wider transmission range than the more common potassium bromide beamsplitters, extending its working range into the far infrared. However, optical-quality CsI crystals are very soft and a hard to cleave or polish and they should also be coated and stored in a desiccator, to minimize interaction with atmospheric water vapors. Caesium iodide atomic chains can be grown inside carbon nanotubes. Accurate measurements reveal that in such chains I atoms appear brighter than Cs atoms despite having a smaller mass and this difference was explained by the charge difference between Cs atoms, inner nanotube walls and I atoms. As a result, Cs atoms are attracted to the walls and vibrate more strongly than I atoms, which are pushed toward the nanotube axis
Caesium iodide
–
Monoatomic caesium halide wires grown inside double-wall
carbon nanotubes.
Caesium iodide
–
Cesium iodide
34.
Thin-film transistor
–
A common substrate is glass, because the primary application of TFTs is in liquid-crystal displays. This differs from the transistor, where the semiconductor material typically is the substrate. TFTs can be using a wide variety of semiconductor materials. Other materials which have used as semiconductors in TFTs include compound semiconductors such as cadmium selenide. An application for hafnium oxide is as a high-κ dielectric, TFTs have also been made using organic materials, referred to as organic field-effect transistors or OTFTs. By using transparent semiconductors and transparent electrodes, such as tin oxide. Such transparent TFTs can be used for construction of video display panels, because conventional substrates cannot withstand high annealing temperatures, the deposition process must be completed under relatively low temperatures. Chemical vapor deposition and physical vapor deposition are applied, the first solution-processed TTFTs, based on zinc oxide, were reported in 2003 by researchers at Oregon State University. The Portuguese laboratory CENIMAT at the Universidade Nova de Lisboa has produced the world’s first completely transparent TFT at room temperature, CENIMAT also developed the first paper transistor, which may lead to applications such as magazines and journal pages with moving images. The best known application of transistors is in TFT LCDs. Transistors are embedded within the panel itself, reducing crosstalk between pixels and improving image stability, as of 2008, many color LCD TVs and monitors use this technology. TFT panels are used in digital radiography applications in general radiography. A TFT is used in direct and indirect capture as a base for the image receptor in medical radiography. AMOLED screens also contain a TFT layer, the most beneficial aspect of TFT technology is its use of a separate transistor for each pixel on the display. Because each transistor is small, the amount of charge needed to control it is also small and this allows for very fast re-drawing of the display. This picture does not include the actual light-source, just the TFT-display matrix
Thin-film transistor
–
Several types of TFT constructions.
35.
Medical diagnosis
–
Medical diagnosis is the process of determining which disease or condition explains a persons symptoms and signs. It is most often referred to as diagnosis with the context being implicit. The information required for diagnosis is typically collected from a history, often, one or more diagnostic procedures, such as diagnostic tests, are also done during the process. Sometimes Posthumous diagnosis is considered a kind of medical diagnosis, Diagnosis is often challenging, because many signs and symptoms are nonspecific. For example, redness of the skin, by itself, is a sign of many disorders, thus differential diagnosis, in which several possible explanations are compared and contrasted, must be performed. This involves the correlation of various pieces of information followed by the recognition and differentiation of patterns, occasionally the process is made easy by a sign or symptom that is pathognomonic. Diagnosis is a component of the procedure of a doctors visit. From the point of view of statistics, the procedure involves classification tests. The first recorded examples of medical diagnosis are found in the writings of Imhotep in ancient Egypt, a Babylonian medical textbook, the Diagnostic Handbook written by Esagil-kin-apli, introduced the use of empiricism, logic and rationality in the diagnosis of an illness or disease. Traditional Chinese Medicine, as described in the Yellow Emperors Inner Canon or Huangdi Neijing, specified four diagnostic methods, inspection, auscultation-olfaction, interrogation, hippocrates was known to make diagnoses by tasting his patients urine and smelling their sweat. This article uses diagnostician as any of these person categories, a diagnostic procedure does not necessarily involve elucidation of the etiology of the diseases or conditions of interest, that is, what caused the disease or condition. Such elucidation can be useful to optimize treatment, further specify the prognosis or prevent recurrence of the disease or condition in the future, the initial task is to detect a medical indication to perform a diagnostic procedure. Indications include, Detection of any deviation from what is known to be normal, such as can be described in terms of, for example, anatomy, physiology, pathology, psychology, a complaint expressed by a patient. The fact that a patient has sought a diagnostician can itself be an indication to perform a diagnostic procedure, even during an already ongoing diagnostic procedure, there can be an indication to perform another, separate, diagnostic procedure for another, potentially concomitant, disease or condition. A diagnostic test is any kind of medical test performed to aid in the diagnosis or detection of disease, Diagnostic tests can also be used to provide prognostic information on people with established disease. Processing of the answers, findings or other results, consultations with other providers and specialists in the field may be sought. There are a number of methods or techniques that can be used in a diagnostic procedure, in reality, a diagnostic procedure may involve components of multiple methods. The final result may also remain a list of possible conditions, the resultant diagnostic opinion by this method can be regarded more or less as a diagnosis of exclusion
Medical diagnosis
–
Radiography is an important tool in diagnosis of certain disorders.
36.
Medical Subject Headings
–
Medical Subject Headings is a comprehensive controlled vocabulary for the purpose of indexing journal articles and books in the life sciences, it serves as a thesaurus that facilitates searching. Created and updated by the United States National Library of Medicine, it is used by the MEDLINE/PubMed article database, MeSH is also used by ClinicalTrials. gov registry to classify which diseases are studied by trials registered in ClinicalTrials. gov. MeSH was introduced in 1960, with the NLMs own index catalogue, the yearly printed version of MeSH was discontinued in 2007 and MeSH is now available online only. It can be browsed and downloaded free of charge through PubMed, originally in English, MeSH has been translated into numerous other languages and allows retrieval of documents from different languages. The 2009 version of MeSH contains a total of 25,186 subject headings, most of these are accompanied by a short description or definition, links to related descriptors, and a list of synonyms or very similar terms. This additional information and the structure make the MeSH essentially a thesaurus. The descriptors or subject headings are arranged in a hierarchy, a given descriptor may appear at several locations in the hierarchical tree. The tree locations carry systematic labels known as numbers. The tree numbers of a given descriptor are subject to change as MeSH is updated, every descriptor also carries a unique alphanumerical ID that will not change. Most subject headings come with a description or definition. See the MeSH description for diabetes type 2 as an example, the explanatory text is written by the MeSH team based on their standard sources if not otherwise stated. References are mostly encyclopaedias and standard textbooks of the subject areas, references for specific statements in the descriptions are not given, instead readers are referred to the bibliography. In addition to the hierarchy, MeSH contains a small number of standard qualifiers. For example, Measles is a descriptor and epidemiology is a qualifier, the epidemiology qualifier can be added to all other disease descriptors. Not all descriptor/qualifier combinations are allowed some of them may be meaningless. In all there are 83 different qualifiers, in addition to the descriptors, MeSH also contains some 139,000 supplementary concept records. These do not belong to the vocabulary as such, instead they enlarge the thesaurus. Many of these records describe chemical substances, by default, a search for a descriptor will include all the descriptors in the hierarchy below the given one
Medical Subject Headings
–
Medical Subject Headings
37.
Attenuation (electromagnetic radiation)
–
In physics, attenuation is the gradual loss in intensity of any kind of flux through a medium. For instance, dark glasses attenuate sunlight, lead attenuates X-rays, in electrical engineering and telecommunications, attenuation affects the propagation of waves and signals in electrical circuits, in optical fibers, and in air. Electrical attenuators and optical attenuators are commonly manufactured components in this field, in many cases, attenuation is an exponential function of the path length through the medium. In chemical spectroscopy, this is known as the Beer–Lambert law, in engineering, attenuation is usually measured in units of decibels per unit length of medium and is represented by the attenuation coefficient of the medium in question. Attenuation also occurs in earthquakes, when the waves move farther away from the epicenter. One area of research in which figures strongly is in ultrasound physics. Attenuation in ultrasound is the reduction in amplitude of the beam as a function of distance through the imaging medium. Accounting for attenuation effects in ultrasound is important because a reduced signal amplitude can affect the quality of the image produced. By knowing the attenuation that an ultrasound beam experiences traveling through a medium, ultrasound attenuation measurement in heterogeneous systems, like emulsions or colloids, yields information on particle size distribution. There is an ISO standard on this technique, ultrasound attenuation can be used for extensional rheology measurement. There are acoustic rheometers that employ Stokes law for measuring extensional viscosity, wave equations which take acoustic attenuation into account can be written on a fractional derivative form, see the article on acoustic attenuation or e. g. the survey paper. Attenuation coefficients are used to different media according to how strongly the transmitted ultrasound amplitude decreases as a function of frequency. Attenuation coefficients vary widely for different media, in biomedical ultrasound imaging however, biological materials and water are the most commonly used media. Ultrasound propagation through homogeneous media is associated only with absorption and can be characterized with absorption coefficient only, propagation through heterogeneous media requires taking into account scattering. When the sun’s radiation reaches the sea-surface, the radiation is attenuated by the water. The intensity of light at depth can be calculated using the Beer-Lambert Law, in clear open waters, visible light is absorbed at the longest wavelengths first. Thus, red, orange, and yellow wavelengths are absorbed at higher water depths, because the blue and violet wavelengths are absorbed last compared to the other wavelengths, open ocean waters appear deep-blue to the eye. In near-shore waters, sea water contains more phytoplankton than the very clear central ocean waters, chlorophyll-a pigments in the phytoplankton absorb light, and the plants themselves scatter light, making coastal waters less clear than open waters
Attenuation (electromagnetic radiation)
–
Frequency-dependent attenuation of electromagnetic radiation in standard atmosphere.
38.
Calcium
–
Calcium is a chemical element with symbol Ca and atomic number 20. Calcium is a soft grayish-yellow alkaline earth metal, fifth-most-abundant element by mass in the Earths crust, the ion Ca2+ is also the fifth-most-abundant dissolved ion in seawater by both molarity and mass, after sodium, chloride, magnesium, and sulfate. Free calcium metal is too reactive to occur in nature, Calcium is produced in supernova nucleosynthesis. Calcium is a trace element in living organisms. It is the most abundant metal by mass in animals, and it is an important constituent of bone, teeth. In cell biology, the movement of the calcium ion into, Calcium carbonate and calcium citrate are often taken as dietary supplements. Calcium is on the World Health Organizations List of Essential Medicines, Calcium has a wide variety of applications, almost all of which are associated with calcium compounds and salts. Calcium metal is used as a deoxidizer, desulfurizer, and decarbonizer for production of ferrous and nonferrous alloys. In steelmaking and production of iron, Ca reacts with oxygen, Calcium carbonate is used in manufacturing cement and mortar, lime, limestone and aids in production in the glass industry. It also has chemical and optical uses as mineral specimens in toothpastes, Calcium hydroxide solution is used to detect the presence of carbon dioxide in a gas sample bubbled through a solution. The solution turns cloudy where CO2 is present, Calcium arsenate is used in insecticides. Calcium carbide is used to make acetylene gas and various plastics, Calcium chloride is used in ice removal and dust control on dirt roads, as a conditioner for concrete, as an additive in canned tomatoes, and to provide body for automobile tires. Calcium citrate is used as a food preservative, Calcium cyclamate is used as a sweetening agent in several countries. In the United States, it has been outlawed as a suspected carcinogen, Calcium gluconate is used as a food additive and in vitamin pills. Calcium hypochlorite is used as a swimming pool disinfectant, as an agent, as an ingredient in deodorant. Calcium permanganate is used in rocket propellant, textile production, as a water sterilizing agent. Calcium phosphate is used as a supplement for animal feed, fertilizer, in production for dough and yeast products, in the manufacture of glass. Calcium phosphide is used in fireworks, rodenticide, torpedoes, Calcium sulfate is used as common blackboard chalk, as well as, in its hemihydrate form, Plaster of Paris
Calcium
–
Calcium, 20 Ca
Calcium
–
Travertine terraces
Pamukkale, Turkey
Calcium
–
'Ain Ghazal figure
Calcium
–
500 milligram calcium supplements made from
calcium carbonate
39.
Radiographic anatomy
–
Radioanatomy is anatomy discipline which involves the study of anatomy through the use of radiographic films. The x-ray film represents two-dimensional image of an object due to the summary projection of different anatomical structures onto a planar surface. It requires certain skills for the interpretation of such images. Radiological anatomy is a component of training for radiologists as well as medical students. RadAnatomy, The KU Radiographic Anatomy Program
Radiographic anatomy
Radiographic anatomy
–
Human chest radiographic anatomy.
40.
Radiologist
–
Radiology is a specialty that uses medical imaging to diagnose and treat diseases seen within the body. Interventional radiology is the performance of medical procedures with the guidance of imaging technologies, the acquisition of medical images is usually carried out by the Radiographer, often known as a Radiologic Technologist. Depending on location, the Diagnostic Radiologist, or Reporting Radiographer, then interprets or reads the images and produces a report of their findings and this report is then transmitted to the Clinician who requested the imaging, either routinely or emergently. Radiographs are produced by transmitting X-rays through a patient, the X-rays are projected through the body onto a detector, an image is formed based on which rays pass through versus those that are absorbed or scattered in the patient. Röntgen discovered X-rays on November 8,1895 and received the first Nobel Prize in Physics for their discovery in 1901, in film-screen radiography, an X-ray tube generates a beam of X-rays, which is aimed at the patient. The film is then developed chemically and an image appears on the film, film-screen radiography is being replaced by computed radiography but more recently by digital radiography and the EOS imaging. In the two latest systems, the X-rays strike sensors that converts the signals generated into digital information, in digital radiography the sensors shape a plate, but in the EOS system, which is a slot-scanning system, a linear sensor vertically scans the patient. Plain radiography was the imaging modality available during the first 50 years of radiology. Due to its availability, speed, and lower costs compared to other modalities, also despite the large amount of data in CT scans, MR scans and other digital-based imaging, there are many disease entities in which the classic diagnosis is obtained by plain radiographs. Examples include various types of arthritis and pneumonia, bone tumors, fractures, congenital skeletal anomalies, mammography and DXA are two applications of low energy projectional radiography, used for the evaluation for breast cancer and osteoporosis, respectively. Fluoroscopy and angiography are special applications of X-ray imaging, in which a fluorescent screen and this allows real-time imaging of structures in motion or augmented with a radiocontrast agent. Two radiocontrast agents are presently in common use, barium sulfate is given orally or rectally for evaluation of the GI tract. Iodine, in multiple forms, is given by oral, rectal, intra-arterial or intravenous routes. Iodine contrast may also be concentrated in areas more or less than in normal tissues. CT imaging uses X-rays in conjunction with computing algorithms to image the body, in CT, an X-ray tube opposite an X-ray detector in a ring-shaped apparatus rotate around a patient, producing a computer-generated cross-sectional image. CT is acquired in the plane, with coronal and sagittal images produced by computer reconstruction. Radiocontrast agents are used with CT for enhanced delineation of anatomy. Although radiographs provide higher resolution, CT can detect more subtle variations in attenuation of X-rays
Radiologist
–
A radiologist interprets medical images on a modern
picture archiving and communication system (PACS) workstation. San Diego, CA, 2010.
Radiologist
–
Madura foot X-ray
Radiologist
–
Radiography of knee in DR-machine at Sandnessjøen Hospital, Norway.
Radiologist
–
Image from a
CT scan of the brain
41.
Projectional Radiography
–
Projectional radiography is the practice of producing two-dimensional images using x-ray radiation. Radiographic exams are performed by radiographers, trained, licensed medical professionals. Projectional radiography is the cornerstone of modern medical imaging, and can be used to image almost every part of the human body, mammography, DXA and dental radiography are specialized variants of projectional radiography. Computed tomography also uses x-radiation, but its different image acquisition parameters allow for images to be acquired in the axial plane, projectional radiography relies on the characteristics of x-ray radiation and knowledge of how it interacts with human tissue to create diagnostic images. X-rays are a form of ionizing radiation, meaning it has sufficient energy to remove electrons from an atom, thus giving it a charge. Ionizing radiation has sufficient energy to human tissue. When an exposure is made, x-ray radiation exits the tube as what is known as the primary beam, when the primary beam passes through the body, some of the radiation is absorbed in a process known as attenuation. Anatomy that is denser has a rate of attenuation than anatomy that is less dense. What remains of the beam after attenuation is known as the remnant beam. The remnant beam is responsible for exposing the image receptor, areas on the image receptor that receive the most radiation will be more heavily exposed, and therefore will be processed as being darker. Conversely, areas on the receptor that receive the least radiation will be less exposed. This is why bone, which is dense, process as being ‘white’ on radio graphs, and the lungs. Radiographic density is the measure of overall darkening of the image, density is a logarithmic unit that describes the ratio between light hitting the film and light being transmitted through the film. A higher radiographic density represents more opaque areas of the film, with digital imaging, however, density may be referred to as brightness. The brightness of the radiograph in digital imaging is determined by computer software, contrast is defined as the difference in radiographic density between adjacent portions of the image. The range between black and white on the final radiograph, high contrast, or short-scale contrast, means there is little gray on the radiograph, and there are fewer gray shades between black and white. Low contrast, or long-scale contrast, means there is much gray on the radiograph, closely related to radiographic contrast is the concept of exposure latitude. Images having a short-scale of contrast will have narrow exposure latitude, images having long-scale contrast will have a wide exposure latitude, that is, the radiographer will be able to utilize a broader range of technical factors to produce a diagnostic-quality image
Projectional Radiography
–
AP and Lateral Elbow X-Ray
Projectional Radiography
–
X-ray under examination
Projectional Radiography
–
Philips Digital X-Ray Equipment
42.
Charge-coupled device
–
A charge-coupled device is a device for the movement of electrical charge, usually from within the device to an area where the charge can be manipulated, for example conversion into a digital value. This is achieved by shifting the signals between stages within the one at a time. CCDs move charge between capacitive bins in the device, with the shift allowing for the transfer of charge between bins, in recent years CCD has become a major technology for digital imaging. In a CCD image sensor, pixels are represented by p-doped metal-oxide-semiconductors capacitors, the charge-coupled device was invented in 1969 at AT&T Bell Labs by Willard Boyle and George E. Smith. The lab was working on bubble memory when Boyle and Smith conceived of the design of what they termed, in their notebook. The device could be used as a shift register, the essence of the design was the ability to transfer charge along the surface of a semiconductor from one storage capacitor to the next. The concept was similar in principle to the device, which was developed at Philips Research Labs during the late 1960s. The first patent on the application of CCDs to imaging was assigned to Michael Tompsett, the initial paper describing the concept listed possible uses as a memory, a delay line, and an imaging device. The first experimental device demonstrating the principle was a row of closely spaced metal squares on a silicon surface electrically accessed by wire bonds. The first working CCD made with integrated circuit technology was a simple 8-bit shift register and this device had input and output circuits and was used to demonstrate its use as a shift register and as a crude eight pixel linear imaging device. Development of the device progressed at a rapid rate, by 1971, Bell researchers led by Michael Tompsett were able to capture images with simple linear devices. Several companies, including Fairchild Semiconductor, RCA and Texas Instruments, picked up on the invention, fairchilds effort, led by ex-Bell researcher Gil Amelio, was the first with commercial devices, and by 1974 had a linear 500-element device and a 2-D100 x 100 pixel device. Steven Sasson, an engineer working for Kodak, invented the first digital still camera using a Fairchild 100 x 100 CCD in 1975. The first KH-11 KENNAN reconnaissance satellite equipped with charge-coupled device array technology for imaging was launched in December 1976, under the leadership of Kazuo Iwama, Sony also started a large development effort on CCDs involving a significant investment. Eventually, Sony managed to mass-produce CCDs for their camcorders, before this happened, Iwama died in August 1982, subsequently, a CCD chip was placed on his tombstone to acknowledge his contribution. He was also awarded the 2012 IEEE Edison Medal For pioneering contributions to imaging devices including CCD Imagers, cameras, in a CCD for capturing images, there is a photoactive region, and a transmission region made out of a shift register. An image is projected through a lens onto the capacitor array, once the array has been exposed to the image, a control circuit causes each capacitor to transfer its contents to its neighbor. The last capacitor in the array dumps its charge into a charge amplifier, by repeating this process, the controlling circuit converts the entire contents of the array in the semiconductor to a sequence of voltages
Charge-coupled device
–
A specially developed CCD used for
ultraviolet imaging in a wire-bonded package
Charge-coupled device
–
George E. Smith and Willard Boyle, 2009
Charge-coupled device
–
"One-dimensional" CCD
image sensor from a
fax machine
Charge-coupled device
–
CCD from a 2.1
megapixel Argus digital camera
43.
3D rendering
–
3D rendering is the 3D computer graphics process of automatically converting 3D wire frame models into 2D images with 3D photorealistic effects or non-photorealistic rendering on a computer. Rendering is the process of creating the actual 2D image or animation from the prepared scene. This can be compared to taking a photo or filming the scene after the setup is finished in real life, several different, and often specialized, rendering methods have been developed. These range from the distinctly non-realistic wireframe rendering through polygon-based rendering, to advanced techniques such as, scanline rendering, ray tracing. Rendering may take from fractions of a second to days for a single image/frame, in general, different methods are better suited for either photo-realistic rendering, or real-time rendering. Rendering for interactive media, such as games and simulations, is calculated and displayed in real time, in real-time rendering, the goal is to show as much information as possible as the eye can process in a fraction of a second. The primary goal is to achieve an as high as possible degree of photorealism at an acceptable minimum rendering speed, rendering software may simulate such visual effects as lens flares, depth of field or motion blur. These are attempts to simulate visual phenomena resulting from the characteristics of cameras. These effects can lend an element of realism to a scene and this is the basic method employed in games, interactive worlds and VRML. The rapid increase in processing power has allowed a progressively higher degree of realism even for real-time rendering, including techniques such as HDR rendering. Real-time rendering is often polygonal and aided by the computers GPU, animations for non-interactive media, such as feature films and video, are rendered much more slowly. Non-real time rendering enables the leveraging of limited processing power in order to obtain higher image quality, rendering times for individual frames may vary from a few seconds to several days for complex scenes. Rendered frames are stored on a hard disk then can be transferred to media such as motion picture film or optical disk. These frames are then displayed sequentially at high rates, typically 24,25, or 30 frames per second. When the goal is photo-realism, techniques such as ray tracing or radiosity are employed and this is the basic method employed in digital media and artistic works. Techniques have been developed for the purpose of simulating other naturally occurring effects, examples of such techniques include particle systems, volumetric sampling, caustics, and subsurface scattering. The rendering process is expensive, given the complex variety of physical processes being simulated. Computer processing power has increased rapidly over the years, allowing for a higher degree of realistic rendering
3D rendering
–
A photo realistic 3D render of 6
computer fans using
radiosity rendering,
DOF and
procedural materials
3D rendering
–
3D computer graphics
3D rendering
–
An example of a ray-traced image that typically takes seconds or minutes to render.
3D rendering
–
Perspective Projection
44.
Radiocontrast
–
Radiocontrast agents are per definition of drugs, but lack therapeutic effects. Contrast medium is used to enhance the visibility of internal structures in X-ray-based imaging techniques such as computed tomography, radiography, radiocontrast agents are typically iodine or barium compounds. Magnetic resonance imaging functions through different principles and thus utilizes different contrast agents and these compounds work by altering the magnetic properties of nearby hydrogen nuclei. Radiocontrast agents used in X-ray examinations can be grouped based on its use, iodine-based contrast media are usually classified as ionic or non-ionic. Both types are used most commonly in radiology due to their relatively harmless interaction with the body, contrast media are primarily used to visualize vessels and changes in tissues on radiography and CT. Contrast media can also be used for tests of the tract, uterus. It may cause the patient to feel as if he or she has urinated on him- or herself and it also puts a metallic taste in the mouth of the patient. Modern intravenous contrast agents are based on iodine. This may be either in an organic compound or an ionic compound. Ionic agents were developed first and are still in use depending on the requirements. Organic agents which covalently bind the iodine have fewer side effects as they do not dissociate into component molecules, many of the side effects are due to the hyperosmolar solution being injected. I. e. they deliver more iodine atoms per molecule, the more iodine, the more dense the X-ray effect. Organic iodine molecules used for contrast include iohexol, iodixanol and ioversol and these contrast agents are sold as clear, colorless water solutions, with the concentration usually expressed as mg I/ml. Modern iodinated contrast agents can be used almost anywhere in the body, most often they are used intravenously, but for various purposes they can also be used intraarterially, intrathecally and intraabdominally – just about any body cavity or potential space. Non-ionic contrast media have lower osmolality and tend to have fewer side-effects, barium sulfate is mainly used in the imaging of the digestive system. The substance exists as a white powder that is made into a slurry with water. Depending on how it is to be administered the compound is mixed with water, thickeners, de-clumping agents, as the barium sulfate doesnt dissolve, this type of contrast agent is an opaque white mixture. It is only used in the tract, it is usually swallowed or administered as an enema
Radiocontrast
–
Example of iodine based contrast in
cerebral angiography
Radiocontrast
–
Example of a DCBE
45.
Dual energy X-ray absorptiometry
–
Dual-energy X-ray absorptiometry is a means of measuring bone mineral density. Two X-ray beams, with different energy levels, are aimed at the patients bones, when soft tissue absorption is subtracted out, the BMD can be determined from the absorption of each beam by bone. Dual-energy X-ray absorptiometry is the most widely used and most thoroughly studied bone density measurement technology, DXA scans are used primarily to evaluate bone mineral density. DXA scans can also be used to total body composition. DXA scans are used to assess adiposity in children, especially to conduct clinical research. Preventive Services Task Force recommends that women over the age of 65 should get a DXA scan, the date at which men should be tested is uncertain but some sources recommend age 70. At risk women should consider getting a scan when their risk is equal to that of a normal 65-year-old woman, special considerations are involved in the use of DXA to assess bone mass in children. Specifically, comparing the bone density of children to the reference data of adults will underestimate the BMD of children. This would lead to an over-diagnosis of osteopenia for children, to avoid an overestimation of bone mineral deficits, BMD scores are commonly compared to reference data for the same gender and age. Also, there are variables in addition to age that are suggested to confound the interpretation of BMD as measured by DXA. One important confounding variable is bone size, DXA has been shown to overestimate the bone mineral density of taller subjects and underestimate the bone mineral density of smaller subjects. This error is due to the way by which DXA calculates BMD, in DXA, bone mineral content is divided by the area of the site being scanned. Because DXA calculates BMD using area, it is not a measurement of true bone mineral density. In order to distinguish DXA BMD from volumetric bone-mineral density, researchers sometimes refer to DXA BMD as a bone mineral density. The confounding effect of differences in size is due to the missing depth value in the calculation of bone mineral density. Despite DXA technologys problems with estimating volume, it is still a fairly accurate measure of bone mineral content, methods to correct for this shortcoming include the calculation of a volume that is approximated from the projected area measure by DXA. DXA BMD results adjusted in this manner are referred to as the bone mineral apparent density and are a ratio of the mineral content versus a cuboidal estimation of the volume of bone. Like the results for aBMD, BMAD results do not accurately represent true bone mineral density, BMAD is used primarily for research purposes and is not yet used in clinical settings
Dual energy X-ray absorptiometry
–
Dual-energy X-ray absorptiometry
Dual energy X-ray absorptiometry
–
DEXA assessment of bone mineral density of the femoral neck (A) and the lumbar spine (B): T scores of - 4.2 and - 4.3 were found at the hip (A) and lumbar spine (B), respectively in a 53-year-old male patient affected with
Fabry disease.
Dual energy X-ray absorptiometry
–
A full-body scan appearing on the screen of a computer linked to a DEXA scanner
46.
Lumbar vertebrae
–
The lumbar vertebrae are, in human anatomy, the five vertebrae between the rib cage and the pelvis. They are designated L1 to L5, starting at the top, the lumbar vertebrae help support the weight of the body, and permit movement. The figure on the left depicts the characteristics of the first through fourth lumbar vertebrae. The fifth vertebra contains certain peculiarities, which are detailed below, as with other vertebrae, each lumbar vertebra consists of a vertebral body and a vertebral arch. The vertebral arch, consisting of a pair of pedicles and a pair of laminae, encloses the vertebral foramen, the vertebral body of each lumbar vertebra is large, wider from side to side than from front to back, and a little thicker in front than in back. It is flattened or slightly concave above and below, concave behind, the pedicles are very strong, directed backward from the upper part of the vertebral body, consequently, the inferior vertebral notches are of considerable depth. The pedicles change in morphology from the upper lumbar to the lower lumbar and they increase in sagittal width from 9 mm to up to 18 mm at L5. They increase in angulation in the plane from 10 degrees to 20 degrees by L5. The pedicle is sometimes used as a portal of entrance into the body for fixation with pedicle screws or for placement of bone cement as with kyphoplasty or vertebroplasty. The laminae are broad, short, and strong and they form the posterior portion of the vertebral arch. In the upper lumbar region the lamina are taller than wide, the lamina connects the spinous process to the pedicles. The vertebral foramen within the arch is triangular, larger than the thoracic vertebrae, the spinous process is thick, broad, and somewhat quadrilateral, it projects backward and ends in a rough, uneven border, thickest below where it is occasionally notched. The superior and inferior articular processes are well-defined, projecting respectively upward and downward from the junctions of pedicles, the facets on the superior processes are concave, and look backward and medialward, those on the inferior are convex, and are directed forward and lateralward. The former are wider apart than the latter, since in the column the inferior articular processes are embraced by the superior processes of the subjacent vertebra. The transverse processes are long and slender and they are horizontal in the upper three lumbar vertebrae and incline a little upward in the lower two. They are situated in front of the articular processes instead of them as in the thoracic vertebrae. Three portions or tubercles can be noticed in a process of a lower lumbar vertebrae, the lateral or costiform process, the mammillary process. The costiform is lateral, the mammillary is superior, and the accessory is inferior, the mammillary is connected in the lumbar region with the back part of the superior articular process
Lumbar vertebrae
–
Lumbar vertebrae
Lumbar vertebrae
–
Position of human lumbar vertebrae (shown in red). It consists of 5 bones, from top to down, L1, L2, L3, L4 and L5.
Lumbar vertebrae
–
Sacralization of the L5 vertebra is seen at the lower right of the image
Lumbar vertebrae
47.
Transverse plane
–
The transverse plane is an imaginary plane that divides the body into superior and inferior parts. It is perpendicular to the coronal and sagittal planes and it is one of the planes of the body used to describe the location of body parts in relation to each other. The other two commonly used terms are the plane and the sagittal plane. Typically located at the level of S1, anatomical terms of location Horizontal plane Coronal plane Sagittal plane
Transverse plane
48.
Radiocontrast agent
–
Radiocontrast agents are per definition of drugs, but lack therapeutic effects. Contrast medium is used to enhance the visibility of internal structures in X-ray-based imaging techniques such as computed tomography, radiography, radiocontrast agents are typically iodine or barium compounds. Magnetic resonance imaging functions through different principles and thus utilizes different contrast agents and these compounds work by altering the magnetic properties of nearby hydrogen nuclei. Radiocontrast agents used in X-ray examinations can be grouped based on its use, iodine-based contrast media are usually classified as ionic or non-ionic. Both types are used most commonly in radiology due to their relatively harmless interaction with the body, contrast media are primarily used to visualize vessels and changes in tissues on radiography and CT. Contrast media can also be used for tests of the tract, uterus. It may cause the patient to feel as if he or she has urinated on him- or herself and it also puts a metallic taste in the mouth of the patient. Modern intravenous contrast agents are based on iodine. This may be either in an organic compound or an ionic compound. Ionic agents were developed first and are still in use depending on the requirements. Organic agents which covalently bind the iodine have fewer side effects as they do not dissociate into component molecules, many of the side effects are due to the hyperosmolar solution being injected. I. e. they deliver more iodine atoms per molecule, the more iodine, the more dense the X-ray effect. Organic iodine molecules used for contrast include iohexol, iodixanol and ioversol and these contrast agents are sold as clear, colorless water solutions, with the concentration usually expressed as mg I/ml. Modern iodinated contrast agents can be used almost anywhere in the body, most often they are used intravenously, but for various purposes they can also be used intraarterially, intrathecally and intraabdominally – just about any body cavity or potential space. Non-ionic contrast media have lower osmolality and tend to have fewer side-effects, barium sulfate is mainly used in the imaging of the digestive system. The substance exists as a white powder that is made into a slurry with water. Depending on how it is to be administered the compound is mixed with water, thickeners, de-clumping agents, as the barium sulfate doesnt dissolve, this type of contrast agent is an opaque white mixture. It is only used in the tract, it is usually swallowed or administered as an enema
Radiocontrast agent
–
Example of iodine based contrast in
cerebral angiography
Radiocontrast agent
–
Example of a DCBE
49.
Non-destructive testing
–
The terms nondestructive examination, nondestructive inspection, and nondestructive evaluation are also commonly used to describe this technology. Because NDT does not permanently alter the article being inspected, it is a valuable technique that can save both money and time in product evaluation, troubleshooting, and research. Common NDT methods include ultrasonic, magnetic-particle, liquid penetrant, radiographic, remote visual inspection, eddy-current testing, innovations in the field of nondestructive testing have had a profound impact on medical imaging, including on echocardiography, medical ultrasonography, and digital radiography. NDT methods may rely upon use of radiation, sound. The inside of a sample can be examined with penetrating radiation, such as X-rays, sound waves are utilized in the case of ultrasonic testing. Contrast between a defect and the bulk of the sample may be enhanced for visual examination by the eye by using liquids to penetrate fatigue cracks. One method involves using dyes, fluorescent or non-fluorescent, in fluids for non-magnetic materials, another commonly used NDT method used on ferrous materials involves the application of fine iron particles that are applied to a part while it is in an externally magnetized state. The particles will be attracted to leakage fields within the test object, Magnetic particle testing can reveal surface & some sub-surface defects within the part. Thermoelectric effect uses thermal properties of an alloy to quickly and easily characterize many alloys, the chemical test, or chemical spot test method, utilizes application of sensitive chemicals that can indicate the presence of individual alloying elements. Electrochemical methods, such as electrochemical fatigue crack sensors, utilize the tendency of metal structural material to oxidize readily in order to detect progressive damage, analyzing and documenting a non-destructive failure mode can also be accomplished using a high-speed camera recording continuously until the failure is detected. Detecting the failure can be accomplished using a detector or stress gauge which produces a signal to trigger the high-speed camera. These high-speed cameras have advanced recording modes to capture some non-destructive failures, after the failure the high-speed camera will stop recording. The capture images can be played back in slow motion showing precisely what happen before, during and after the non-destructive event, NDT is used in a variety of settings that covers a wide range of industrial activity, with new NDT methods and applications, being continuously developed. In manufacturing, welds are used to join two or more metal parts. Because these connections may encounter loads and fatigue during product lifetime, the typical welding defects could cause a structure to break or a pipeline to rupture. Welding techniques may also be monitored with acoustic emission techniques before production to design the best set of parameters to use to properly join two materials. In the case of stress or safety critical welds, weld monitoring will be employed to confirm the specified welding parameters are being adhered to those stated in the welding procedure. This verifies the weld as correct to procedure prior to nondestructive evaluation, structure can be complex systems that undergo different loads during their lifetime, e. g. Lithium-ion batteries
Non-destructive testing
–
Chest radiography indicating a peripheral
bronchial carcinoma.
Non-destructive testing
–
1. Section of material with a surface-breaking crack that is not visible to the naked eye. 2. Penetrant is applied to the surface. 3. Excess penetrant is removed. 4. Developer is applied, rendering the crack visible.
Non-destructive testing
–
An example of a 3D replicating technique. The flexible high-resolution replicas allow surfaces to be examined and measured under laboratory conditions. A replica can be taken from all solid materials.
50.
X-rays
–
X-radiation is a form of electromagnetic radiation. Most X-rays have a wavelength ranging from 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz, X-ray wavelengths are shorter than those of UV rays and typically longer than those of gamma rays. Spelling of X-ray in the English language includes the variants x-ray, xray, X-rays with high photon energies are called hard X-rays, while those with lower energy are called soft X-rays. Due to their ability, hard X-rays are widely used to image the inside of objects, e. g. in medical radiography. The term X-ray is metonymically used to refer to an image produced using this method. Since the wavelengths of hard X-rays are similar to the size of atoms they are useful for determining crystal structures by X-ray crystallography. By contrast, soft X-rays are easily absorbed in air, the length of 600 eV X-rays in water is less than 1 micrometer. There is no consensus for a definition distinguishing between X-rays and gamma rays, one common practice is to distinguish between the two types of radiation based on their source, X-rays are emitted by electrons, while gamma rays are emitted by the atomic nucleus. This definition has problems, other processes also can generate these high-energy photons. One common alternative is to distinguish X- and gamma radiation on the basis of wavelength, with radiation shorter than some arbitrary wavelength, such as 10−11 m and this criterion assigns a photon to an unambiguous category, but is only possible if wavelength is known. Occasionally, one term or the other is used in specific contexts due to precedent, based on measurement technique. Thus, gamma-rays generated for medical and industrial uses, for radiotherapy, in the ranges of 6–20 MeV. X-ray photons carry enough energy to ionize atoms and disrupt molecular bonds and this makes it a type of ionizing radiation, and therefore harmful to living tissue. A very high radiation dose over a period of time causes radiation sickness. In medical imaging this increased risk is generally greatly outweighed by the benefits of the examination. The ionizing capability of X-rays can be utilized in treatment to kill malignant cells using radiation therapy. It is also used for material characterization using X-ray spectroscopy, hard X-rays can traverse relatively thick objects without being much absorbed or scattered. For this reason, X-rays are widely used to image the inside of visually opaque objects, the most often seen applications are in medical radiography and airport security scanners, but similar techniques are also important in industry and research
X-rays
–
Spectrum of the X-rays emitted by an X-ray tube with a
rhodium target, operated at 60
kV. The smooth, continuous curve is due to
bremsstrahlung, and the spikes are
characteristic K lines for rhodium atoms.
X-rays
–
X-rays are part of the
electromagnetic spectrum, with wavelengths shorter than
visible light. Different applications use different parts of the X-ray spectrum.
X-rays
–
A
chest radiograph of a female, demonstrating a
hiatus hernia
X-rays
–
An arm radiograph, demonstrating broken
ulna and
radius with implanted
internal fixation.
.
