Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
118 Cards in this Set
- Front
- Back
|
Aberration
|
An undersirable characteristic of a lens or optical system. It prevents the lens from providing an exact reproduction of the original subject, by degrading or distorting the image
|
|
|
Absorbed Dose
|
Means the energy imparted by ionizing radiation per unit mass of irradiated material. The unit of absorbed dose are the rad and the gray (Gy)
|
|
|
Absorption (Differential, rare earth screen, specific rate of, visible light)
|
The transfer of energy from an X-ray beam to the atoms or molecules of the matter through which it passes. The process whereby radiation is stopped and reduced in intensity as it passes through matter. Lead, which is denser than most materials, is one of the best absorbers of x-rays.
|
|
|
Active trace:
|
The part of the television scanning system utlized to reproduce the subject
|
|
|
Adult
|
Means an individual 18 years or more of age
|
|
|
ALARA
|
Acronym for "as low as reasonably achievable" means making every reasonable effort to maintain exposures to radiation as far below the dose limits in this part as is practical consistent with the purpose for which the licensed activity is undertaken, taking into account the state of technology, the economics of improvements in relation to the state of technology, the economics of improvements in relation to the benefits to the public health safety, and other societal and socioeconomic considerations and in relation to utilization of nuclear energy and licensed materials in the public interest
|
|
|
Algorithm
|
A formula or set of steps for solving a problem
|
|
|
Aluminum Equivalent
|
The thickness of type 1100 aluminum alloy affording the same attenuation, under specific conditions, as the material in question
|
|
|
Ambient
|
The natural or inherent environment in which some event or activity is to take place. For example, ambient lighting would refer to the normal level of illumination in a particular area
|
|
|
Ampere
|
The unit of electrical current equal to the steady current produced by one volt applied across a resistance of one ohm. This electrical current determines the quantity of x-rays produced at the anode (target) of the x-ray tube.
|
|
|
Amplifier
|
A device in which an electrical signal may be strengthened
|
|
|
Analog
|
A continuous variable electrical signal
|
|
|
Analog-to-Digital Converter (ADC)
|
Device that converts an analog signal into a digital signal
|
|
|
Angstrom (A)
|
A unit of length used primarily to indicate the wavelength of the visible or shorter wavelength portion of the spectrum. One angstrom equals 10^-10 meters
|
|
|
Angular magnification
|
A measure of the angle subtended at the eye by an object compared to some fixed standard reference. The object for the eye may be a real or virtual image created in the optical instrument.
|
|
|
Anode
|
A positive electrode, also referred to as a target, toward which electrons are accelerated from the cathode. The target is usually composed of tungsten. When these electrons hit the anode or target some of their kinetic energy is converted to x-rays
|
|
|
Aperture:
|
(For CT)-the opening in the collimation that allows radiation to reach the detector
|
|
|
Artifact
|
Any density or mark on a radiograph that is caused by something not belonging to the part being x-rayed
|
|
|
II-Tube artifact
|
Minute particles of imperfection within an image tube. They appear as small dark spots on the output screen of the II-Tube
|
|
|
Attenuation
|
The process by which an x-ray beam of radiation is reduced in intensity by absorption or scattering when passing through material
|
|
|
Attenuation Block
|
A block or stack of material with a cross section larger than the beam with a total thickness equivalent to 3.8 cm of type 1100 aluminum
|
|
|
Automatic Exposure Control (AEC)
|
Means a device which automatically controls one or more technical factors in order to obtain at a prescribed location a required quantity of radiation.
|
|
|
Bandwidth
|
The total number of cycles per unit of time (usually one second) which may be used to modulate the electron beam in a television camera
|
|
|
Barrier, Protective
|
Barrier or attenuating materials used to reduce radiation exposure
|
|
|
Primary Barrier
|
Barrier sufficient to attenuate the useful beam to the required degree
|
|
|
Secondary Barrier
|
Barrier sufficient to attenuate stray radiation to the required degre
|
|
|
Base Density
|
The optical density of a film is the optical density that would result if an unexposed film were processed through the fixer, washer, and dryer, without first passing through the developer. The optical density is due to the supporting base of the film alone.
|
|
|
Base Plus Fog Density
|
The optical density of a film due to its base density plus any action of the developer on the unexposed silver halide crystals. The base plus fog density can be measure by passing an unexposed film through the entire processing cycle and measuring the resultant optical density with a densitometer.
|
|
|
Beam
|
A flow of electromagnetic radiation (see useful beam)
|
|
|
Beam Limiting/Defining Device
|
A device in which provides a means to restrict the dimensions of the useful beam. In regions outside the beam the device, if in integral part of the radiation-producing equipment, shall provide shielding adequate to meet the leakage requirements of the source assembly to which it is attached.
|
|
|
Beam Splitter
|
An optical element used to divide a beam of light so that it may be simultaneously projected in two different directions
|
|
|
The Law Of Bergonie and Tribondeau
|
The empirical rule which states that the radiosensitivity of the tissues depends on the number of undifferentiated cells which the tissue contains, the degree of mitotic activity in the tissue and the length of time the cells of the tissue stay in active proliferation. Generally, the more undifferentiated the cell line, the greater the radiosensitivity.
|
|
|
Black Level
|
The level in the composite video signal at which the kinescopic electron beam is completely extinguished.
|
|
|
Blanking
|
That period of time during the television scanning process when the electron beam is automatically driven to the black level for retrace
|
|
|
Blind spot
|
The point where the optic nerve enters the retina. Since there is an absence of all light sensitive cells, no vision is developed.
|
|
|
Bone Marrow
|
A soft tissue which constitutes the central filling of many bones and serves as a producer of red blood cells. Bone marrow is especially sensitive to X-rays.
|
|
|
Boost Position
|
The high level control setting of fluoroscopic equipment that enables it to override routine exposure limits.
|
|
|
Bucky
|
See Grid
|
|
|
Caliper
|
An instrument to measure patient thickness. The measurement should be done where the central ray (CR) enters and exits the body part.
|
|
|
Carcinogenic
|
Producing Cancer
|
|
|
Cassette
|
A light-tight film holder containing intensifying screens mounted within front and back structures that are hinged together and which are made of low x-ray absorption material
|
|
|
Cataract
|
A clouding of crystalline lens of the eye which obstructs the passage of light
|
|
|
Cathode
|
A negative electrode; electrode in the x-ray tube from which electrons are emitted. It consists of one or two filaments and a focusing cup.
|
|
|
Centigray
|
0.01 Gray. 1cGy equals one rad
|
|
|
Central Ray (Central beam) (CR)
|
Refers to the x-rays in the center of the useful or primary beam
|
|
|
Certified Source Assembly
|
A source assembly certified by an assembler to comply with the leakage requirements of the Radiation Control for Health and Safety Act of 1968
|
|
|
Chamber, Pocket Ion
|
A small pocket-sized ionization chamber used for monitoring radiation exposure of personnel. Before use it is given a charge and the amount of discharge during the period of use is a measure of the total radiation exposure during the period.
|
|
|
Characteristic Curve
|
A type of input-output curve used to express the change in density with the change in radiation dose of the photographic or x-ray film. Aso sometimes known as an H&D curve. The characteristic curve graphically demonstrates the relationship between the density and radiation dose. In technical terms: Characteristic curve is a graph of photographic density against logarithm of radiation dose.
|
|
|
Chromosome
|
Important macromolecules found in all body cells. Chromosomes contain the genes of heredity-determining units
|
|
|
Chronic Exposure
|
Irradiation that is spread out over a period of years
|
|
|
Cine Camera
|
A camera used for recording motion- in cinefluoroscopy one that usually visualizes either 16 or 35 mm film. Frame rates may be on the order of 15 to 60 frames per second.
|
|
|
Cinefluorography or Cine
|
The production of motion picture photographic records of the image formed on the output phosphor of an image intensifier by the action of x-rays transmitted through the patient (often called cineradiography).
|
|
|
Cineradiography
|
Means the making of a motion picture record of the successive images appearing on a fluorescent screen
|
|
|
Closed Circuit
|
The distribution of a television signal by means of a coaxial cable or microwave transmission. Permits selective transmission as compared to a normal broadcast.
|
|
|
Coaxial cable
|
A type of special cable used to transmit the composite video signal from the camera to the monitor and or magnetic recorders. THe signal conductor in the center of the cable has a protective grounded metallic sheath around it.
|
|
|
Collective Dose
|
Is the sum of the individual doses received in a given period of time by a specified population from exposure to a specified source of radiation
|
|
|
Collimating Lens
|
A highly corrected lens used to collect light form some source and project it into space as a family of parallel-light beams.
|
|
|
Collimator
|
A device for restricting/confining/limiting a beam of radiation within an assigned solid angle
|
|
|
Color Translation
|
A technique for rendering a fluoroscopic or radiographic image in a more dramatic manner. The original gray scale is converted into a multicolored scale
|
|
|
Compliance Test
|
A compliance test is performed on x-ray equipment to ensure that the x-ray unit meets the radiation safety regulations.
|
|
|
Composite video signal
|
The composite television signal transmitted from the camera, consisting of three parts: Video, blanking, and synchronizing pulses.
|
|
|
Compression Cone
|
This device is an attachment for use in fluoroscopy of the GI tract and serves to permit the examiner to apply pressure to various parts being examined, displace some of the overlying structures, and improve the examination.
|
|
|
Compton effect or scattering
|
An interaction between an incoming x-ray photon and an outer shell electron of an atom of the irradiated object in which the photon surrenders a portion of its kinetic energy to dislodge the electron from its orbit and then continues on its way but in a new direction. This process accounts for most of the scattered radiation produced during diagnostic x-ray examinations.
|
|
|
Computed Tomography (CT)
|
See tomography
|
|
|
Cone
|
A round/circular metal tube/shield attached to the x-ray tube housing or placed in front of the x-ray tube to limit the size of the x-ray beam to a predetermined size and shape
|
|
|
Cones
|
One of the two types of cells contained in the retina of the human eye. Cones are less sensitive than are the rods, but are responsible for creating color differences.
|
|
|
Contrast
|
In radiology, contrast is defined as the difference in density between light and dark areas on the processed film. Contrast can be measured from a characteristic or H&D curve by finding the tangent of the straight line portion of the curve.
|
|
|
Contrast (Fluoroscopy image)
|
The ratio of the brightness on the open field at a given exposure to the brightness underneath a lead disk covering 10 percent of the useful central imaging area in a second exposure. Contrast for modern image intensifiers exceeds 15:1
|
|
|
Contrast Agents or Media
|
Low toxicity materials such as barium or iodine that posses a high atomic numbers and thus decreases the transmission of x-rays. The absorption of x-rays in barium and iodine is much greater than that in bone and tissue which have much lower effective atomic numbers. When these materials are administers to vessels or organs they allow increased visualization of their structures. The use of contrast agents in diagnostic radiology is derived from their ability to enhance the photoelectric effect.
|
|
|
Control Chart
|
A chart used to record and control the performance of a radiographic processor as a function of time
|
|
|
Controlled Area
|
Means an area, outside of a restricted area but inside the site boundary, access to which can be limited by the licensee for any reason (it is an area in which radiation safety rules are enforced)
|
|
|
Coulomb
|
Means a unit of electric charge equal to 1 ampere-second (The quantity of electricity transferred by a current of one ampere in one second).
|
|
|
Conversion Factor (of an image intensifier)
|
The quotient of the luminescense of the output phosphor of the image intensifier divided by the kerma rat at the input phosphor. The recommended means of expressing the luminance gain of an image intensifier tube. Defined as being the ratio of the output screen luminance in candela per square meter to the input exposure rate in millirads per second
|
|
|
Creep
|
the horizontal or vertical movement of fluoroscopic equipment during an x-ray examination
|
|
|
CT Number
|
One of a set of numbers on a linear scale which are related to the linear attenuation coefficients calculated by a computer tomographic device. One of the specific set of CT numbers on a scale from -1000 for air to +1000 for bone, with water equal zero, which is called a hounsfield unit.
|
|
|
Cycle
|
A complete sets of events, or changes, during which some process of a periodic nature returns to its original starting point. In the case of a television system, it is used to measure the length of time it takes to start, stop, and prepare to start an electrical signal.
|
|
|
Dead-Man Switch
|
Means a switch so constructed that a circuit-closing contact can only be maintained by continuous pressure by the operator
|
|
|
Deflection
|
In television, a sweeping movement of an electron beam through an angle in order to generate the raster. The beam deflection is usually caused by creating a magnetic field around the electron beam.
|
|
|
Declared Pregnant Woman
|
Mens a woman who has voluntarily informed her employer, in writing, of her pregnancy and the estimated date of conception.
|
|
|
Deep-Dose Equivalent
|
Applies to external whole-body exposure and is the dose equivalent in a tissue depth of 1 cm (1000 mg/cm^2)
|
|
|
Densitometer
|
An instrument used to measure film density that is the degree of blackening of film by measuring the ratio of the light intensity incident on the film to the light intensity transmitted through the film. (The densitometer is a device designed to measure the optical density of an exposed and processed film. It means the density of the individual steps on films exposed by a sensitometer, and is commonly used for daily processor quality control)
|
|
|
Density
|
Film blackening or the amount of light transmitted through the film. (The density on a radiograph is related to the amount of silver deposited on the film base)
|
|
|
Department
|
Means the State department of health services
|
|
|
Depth of Focus
|
The allowable out-of-focus condition in the image plane that may be tolerated and still maintain a specified resolving power
|
|
|
Detail (Definition)
|
In radiography, detail refers to the sharpness of structure lines or contour lines on the processed films
|
|
|
Developer
|
The chemical solution (alkaline) used in film processing that makes the latent image visible
|
|
|
Developer Replenishment
|
The purpose of developer replenishment is to maintain the proper alkalinity, chemical activity, and level of solution in the developer tank
|
|
|
Diagnostic Source Assembly
|
A diagnostic source housing (x-ray tube housing) assembly with a beam limiting device attached. The assembly shall be so constructed that the leakage radiation air kerma measured at a distance of one meter from the source does not exceed 1mGy in one hour when the source is operated at its leakage technique factors.
|
|
|
Diagnostic-type Tube Housing
|
Means an x-ray tube housing so constructed that the leakage radiation measured at a distance of 1 meter from the source cannot exceed 100 millirads in 1 hour when the tube is operated at its maximum continuous rate of current for the maximum rated tube potential
|
|
|
Diaphragm
|
A plate, usually lead, with a central aperature so placed as to restrict the useful x-ray beam. See collimator
|
|
|
Diffraction
|
The spreading of a beam of light or other electromagnetic radiation when passing through an aperture or over an opaque edge.
|
|
|
Diffuse Reflection
|
One of two types of reflection realized when light strikes a diffusing or matte surface such that light is reflected in a scattered pattern
|
|
|
Digital
|
Input that has a restricted number of discrete, or limited, values.
|
|
|
Digital Radiography
|
A diagnostic procedure using an appropriate radiation source and an imaging system which collects, processes, stores, recalls, and presents image information in a digital rather than analog fashion.
|
|
|
Digital Subtraction
|
An image processing procedure used to improve image contrast by subtracting one digital image from another
|
|
|
Digital-to-Analog Converter (DAC)
|
Device that converts digital signals into analog signals
|
|
|
Diopter
|
A measurement of the power of a lens; defined as being the reciprocal of the focal length of the lens measured in meters
|
|
|
Direct Effect
|
The effect of ionizing particles interacting directly with (Transferring their energy to) biologic macromolecules such as DNA, RNA, ATP, proteins or enzymes: the chemical bonds of these macromolecules break and they become abnormal structures.
|
|
|
Dispersion
|
The decompression of white light into its component colors, most commonly done by passing the light through a prism
|
|
|
Distortion
|
Unequal magnification of different portions of body area being x-rayed. A variation in magnification across the field of an image. If a camera lens has distortion, the image it produces, of a square object, will have curved lines leading to either barrel or pin cushion shapes.
|
|
|
Dominant Mutation
|
A genetic mutation that will probably be expressed in the offspring.
|
|
|
Dose or radiation dose
|
Is a genetic term that means absorbed dose, dose equivalent, effective dose equivalent, committed dose equivalent, committed dose equivalent, or total effective dose equivalent, as defined in other paragraphs of this section.
|
|
|
Absorbed dose
|
The amount of energy imparted by ionizing radiation per unit mass of irradiated material. The units of absorbed dose are the rad (1 rad equals 100ergs per gram) and the gray (gy). The SI unit of absorbed dose is the gray. There are 100 rads per Gy.
|
|
|
Dose Equivalent
|
Means the product of the absorbed dose in tissue, quality factor, and all other necessary modifying factors at the location of interest. The units of dose equivalent are the rem and sievert.
|
|
|
Gonad Dose
|
The amount of radiation absorbed by the gonads resulting fro any part of the body being exposed to x-rays.
|
|
|
Dose Rate
|
Absorbed dose (Or dose equivalent) delivered per unit of time
|
|
|
Dosimeter
|
An instrument used to detect and measure accumulated radiation exposure
|
|
|
Personal Dosimeters
|
Devices designed to be worn or carried by an individual for the purpose of determining the dose equivalent received (e.g., film badges, pocket chambers, pocket dosimeters, ring badges, thermoluminescent dosimeters, etc)
|
|
|
Personal Dosimetry
|
The use of instrument and associated procedures (including calibration and quality assurance) to ascertain the radiation dose absorbed by personnel
|
|
|
Dosimetry processor
|
Means an individual or organization that processes and evaluations individual monitoring equipment in order to determine the radiation dose delivered to the equipment.
|
|
|
Dropouts
|
Minute blank spots in the magnetic recording media. They cause the loss of part or all of a horizontal line
|
|
|
Dual Field Tubes
|
One type of x-ray image intensifier tube in which the input screen is a fixed size, but having the capability of displaying this input screen on the output screen at two different sizes. The two field sizes are created by changing the "crossover" point of the electron beam.
|
|
|
Duty Factor
|
The ratio of on-to-off time of some machine or process. A 100 percent duty factor would indicate continual usage. A 50 percent duty factor would indicate an average of 1/2 off and 1/2 on
|
|
|
Dynamic Range
|
The maximum black-to-white range of which the television system is capable
|
|
|
Dynode
|
That section of a photomultiplier tube in which secondary electrons are emitted, thus providing amplification
|
|
|
Effective Dose Equivalent
|
The sum of the products of the dose equivalent to the organ or tissue and the weighting factor applicable to each of the body organs or tissues that are irradiated
|
|
|
Elective Examination
|
An examination not requiring immediate execution and therefore able to be planned for the patient's convenience and safety
|
|
|
Electron Volt
|
A unit of energy equivalent to the energy gained by an electron in passing through a potential difference of one volt.
|
