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;
131 Cards in this Set
- Front
- Back
|
The 3 parts of the imaging system
|
x-ray tube, operating console, and high voltage generator
|
|
|
Where are electrons produced
|
filament
|
|
|
What type of tranformer is the filament transformer?
|
step down
|
|
|
What is the function of the focusing cup?
|
has a negative charge, so it repels and directs the electrons to the anode target
|
|
|
This target interaction occurs with the slowing down of electrons as it gets close to, but does not hit the nucleus.
|
Bremsstrahlung
|
|
|
This target interaction occurs when an inner shell electron is ejected and photons are given off as the the other electrons "cascade" down to fill vacencies.
|
Characteristic
|
|
|
What happens to wavelength as x-ray energy increases?
|
decreases
|
|
|
What happens to wavelength as frequency increases?
|
decreases
|
|
|
X-ray beam quality is controlled by:
|
kVp
|
|
|
x-ray beam quantity is controlled by:
|
mAs
|
|
|
Electromagnetic energy (radiation) intensity is inversely related to the square of the distance from the source. This is the :
|
Inverse Square Law
|
|
|
At what speed do x-rays travel
|
speed of light
|
|
|
In this photon interaction with matter an outer shell electron is ionized, the photon loses energy and is scattered in a different direction
|
Compton
|
|
|
In this interaction with matter, the incedent photon is absorbed and an inner shell electron is ionized
|
Photoelectric
|
|
|
With this photon interaction with matter, there is no loss in energy, but the photon changes direction. No ionization takes place
|
Coherent (Classical)
|
|
|
The reduction in the total number of photons as it passes through matter
|
attenuation
|
|
|
If the body part is more dense (bone vs muscle) is more or less radiation absorbed?
|
more
|
|
|
If the atomic number of the tissue increases, attenuation
|
increases
|
|
|
This component of the x-ray circuit adjusts the in-coming voltage to exactly 220 Volts
|
Line voltage compensator
|
|
|
60 pulses/second is produced with ______ rectification
|
half wave
|
|
|
A single phase machine's timer can be tested with___
|
a manual spinning top
|
|
|
A 3 phase machine's timere can be tested with a ____
|
synchronous spinning top
|
|
|
The boiling off of electrons
|
thermionic emission
|
|
|
What is the target made of?
|
Tungsten
|
|
|
The line-focus principle results in an ________size much less than the actual focal spot size
|
effective focal spot
|
|
|
What kind of a motor drives the rotating anode?
|
Induction Motor
|
|
|
These timers measure the quantity of radiation reaching the IR and automatically terminates the exposure when sufficient radiation to provide the required density is obtained
|
Automatic Exposure Control
|
|
|
Density adjustments on an AEC are set at _____% increments
|
30
|
|
|
3 primary parts of the High Voltage Generator
|
Step up tranformer, filament transformer, rectifiers
|
|
|
Controlls filament temperature
|
filament current
|
|
|
The filament transformer is a _____ _______ transformer
|
step down
|
|
|
Does the high voltage step up transformer operate on AC or DC?
|
AC
|
|
|
Converts AC to DC
|
rectifier
|
|
|
At least 4 diodes are required for:
|
Full wave rectification
|
|
|
Function of Image Intensifier
|
converts photons to visible light
|
|
|
Function of the input phosphor in an Image Intensifier
|
converts x-rays to visible light
|
|
|
function of the output phosphor in an Image intensifier
|
convert electrons to light
|
|
|
This helps to maintain a satisfactory image brightness during fluoroscopy studies by automatically varying kVp and/or mA
|
Automatic Brightness Control
|
|
|
A measure of the brightness of a source such as a digital display device; expressed in units of candela/m or nit
|
luminance
|
|
|
lighting in the room in which images areviewed
|
abient lighting
|
|
|
controlled by the matrix size
|
spatial resolution
|
|
|
brightness--the ability to distinguish many shades of gray from black to white
|
contrast resolution/dynamic range
|
|
|
Which has better contrast resolution--digital systems or film/screen systems?
|
digital
|
|
|
controls image density--brings density differences into the visual range
|
window level function
|
|
|
gray scale expansion or compression--controls image contrast
|
window width function
|
|
|
Used in imaging plates in CR
|
photostimulable phosphor
|
|
|
Are CR imaging plates more or less sensitive to scatter than film?
|
more
|
|
|
Directly converts x-ray photons to electronic signal
|
Direct flat panel detectors
|
|
|
work by a two part process--photons converted to light, then light to electronic signal (by the photodetector)
|
Indirect flat panel detectors
|
|
|
What is the difference between a stationary grid and a bucky grid system?
|
Bucky reciprocates during exposure
|
|
|
The faster the IRS, the ____ dose to patient
|
less
|
|
|
The slower the IRS, the _____ recorded detail
|
more
|
|
|
A 200 speed screen will require _____ as much exposure as a 400 speed screen
|
twice
|
|
|
A 12:1 grid cleans up ____ scatter than an 8:1 grid
|
more
|
|
|
A ______ grid requires that a certain SID be used.
|
focused
|
|
|
If a focused grid is inverted, there will be a decrease in density ________
|
At the edges of the image
|
|
|
Using a grid ______ scatter production
|
does nothing for
|
|
|
A 16:1 grid will require _____ exposure than an 8:1 grid
|
more
|
|
|
variation between the x-ray field and image receptor size must be within _____ of SID
|
+/-2%
|
|
|
x-ray beam bucky tray alignment must be within _____ of SID
|
+/-1%
|
|
|
3 parts of a QC program
|
visual inspection, environmental inspection, and performance testing
|
|
|
occurs when there are not enough photons to create the image
|
Quantum mottle
|
|
|
data from previous images will interfere with current image data
|
phantom image artifact
|
|
|
appear as dark bands at the interfaces of structures that differ widely in brightness level such as barium examinations or metal prosthesis
|
halo artifact
|
|
|
Area on the anode target that is exposed to electrons from the tube current
|
Actual focal-spot size
|
|
|
Computer-adapted mathematical calculation applied to raw data during image reconstruction
|
Algorithm
|
|
|
Oscillation of electricity in both directions within a conductor.
|
Alternating current (AC)
|
|
|
Technique by which graphics on the console guide the technologist in selection of a desired kVp and mAs.
|
Anatomically programmed radiography (APR)
|
|
|
Positively charged side of an x-ray tube that contains the target
|
Anode
|
|
|
Simple beam-restricting device that attaches a lead-lined metal diaphragm to the head of the x-ray tube.
|
Aperture diaphragm
|
|
|
Principle stating that the voltage received and the voltage provided are directly related to the number of turns of the transformer enclosed by the respective connections.
|
Autotransformer law
|
|
|
Device that provides a means of restricting the size of an x-ray field.
|
Beam-limiting device
|
|
|
Ability of the image intensifier to increase the illumination level of the image
|
Brightness gain
|
|
|
Ratio of incident radiation to transmitted radiation through a grid; ratio of patient dose with and without a grid.
|
Bucky factor (B)
|
|
|
Protective cover that automatically shields the Bucky slot opening during fluoroscopic examinations when the Bucky tray is at the foot of the table.
|
Bucky slot cover
|
|
|
Negative side of the x-ray tube; contains the filament and the focusing cup.
|
Cathode
|
|
|
Device used to restrict x-ray beam size and shape.
|
Collimator
|
|
|
Material inserted between an x-ray source and a patient to shape the intensity of the x-ray beam. An x-ray beam filter is designed to make the remnant beam more uniform in intensity.
|
Compensating filter
|
|
|
Circular metal tube that attaches to x-ray tube housing to limit the beam size and shape.
|
Cone
|
|
|
Type of vacuum tube in use today that allows x-ray intensity and energy to be selected separately and accurately
|
Coolidge tube
|
|
|
Grid on which lead strips run parallel to the long and short axes
|
Crossed grid/ cross-hatched grid
|
|
|
Instrument that measures the optical density of exposed film
|
Densitometer
|
|
|
Digital x-ray imaging system that produces a series of dynamic images with the use of an area x-ray beam and an image intensifier.
|
Digital fluoroscopy (DF)
|
|
|
Static images produced with a fan x-ray beam intercepted by a linear array of radiation detectors or an area x-ray beam intercepted by a photostimulable phosphor plate or a direct-capture solid-state device
|
Digital radiography (DR)
|
|
|
Flow of electricity in only one direction within a conductor.
|
Direct current (DC)
|
|
|
Instrument that detects and measures exposure to ionizing radiation.
|
Dosimeter
|
|
|
Radiographic film that has an emulsion coating on both sides of the base and a layer of supercoat over each emulsion.
|
Double-emulsion film
|
|
|
Range of values that can be displayed by an imaging system; shades of gray
|
Dynamic range
|
|
|
Accentuation of the interface between different tissues
|
Edge enhancement
|
|
|
Area projected onto the patient and the image receptor
|
Effective focal-spot
|
|
|
Ability of a radiographic unit to produce a constant radiation output for various combinations of mA and exposure time
|
Exposure linearity
|
|
|
Image matrix size provided by digital x-ray imaging systems
|
Field of view (FOV)
|
|
|
Part of the cathode that emits electrons, resulting in a tube current.
|
Filament
|
|
|
Removal of low-energy x-rays from the useful beam with aluminum or another metal. It results in increased beam quality and reduced patient dose.
|
Filtration
|
|
|
Emission of visible light only during stimulation.
|
Fluorescence
|
|
|
Ratio of the number of light photons at the output phosphor to the number of x-rays at the input phosphor
|
Flux gain
|
|
|
Region of the anode target in which electrons interact to produce x-rays.
|
Focal spot
|
|
|
Radiographic grid constructed so that the grid strips converge on an imaginary line
|
Focused grid
|
|
|
Metal shroud that surrounds the filament.
|
Focusing cup
|
|
|
Number of cycles or wavelengths of a simple harmonic motion per unit time. Expressed in Hertz (Hz). 1 Hz=1 cycle/s.
|
Frequency
|
|
|
Imaginary pivot point about which the x-ray tube and the image receptor move.
|
fulcrum
|
|
|
Circuit in which the negative half-cycle corresponding to the inverse voltage is reversed, so a positive voltage is always directed across the x-ray tube.
|
Full-wave rectification
|
|
|
Device used to reduce the intensity of scatter radiation in the remnant x-ray beam.
|
Grid
|
|
|
Absence of optical density on a radiograph caused by unintended x-ray absorption in a grid
|
Grid cutoff
|
|
|
Number of grid lines per inch or centimeter.
|
Grid frequency
|
|
|
Ratio of grid height to grid strip separation
|
Grid ratio
|
|
|
Thickness of absorber necessary to reduce an x-ray beam to half its original intensity
|
Half-value layer (HVL)
|
|
|
Condition in which the voltage is not allowed to swing negatively during the negative half of its cycle.
|
Half-wave rectification
|
|
|
Absorption of x-rays in the heel of the target, resulting in reduced x-ray intensity to the anode side of the central axis
|
Heel effect
|
|
|
One of three principal parts of an x-ray imaging system; it is always close to the x-ray tube.
|
High-voltage generator
|
|
|
Electronic vacuum tube that amplifies a fluoroscopic image to reduce patient dose.
|
Image intensifier
|
|
|
Medium that transforms the x-ray beam into a visible image; radiographic film or a phosphorescent screen.
|
Image receptor (IR)
|
|
|
Filtration of useful x-ray beams provided by the permanently installed components of an x-ray tube housing assembly and the glass window of an x-ray tube.
|
Inherent filtration
|
|
|
Sensitive phosphor that converts x-rays to light to shorten exposure time and reduce patient dose.
|
Intensifying screen
|
|
|
Ratio of exposure without screens to that with screens to produce the same optical density.
|
Intensification factor (IF)
|
|
|
Imaging modality in which the x-ray tube is mechanically attached to the image receptor and moves in one direction as the image receptor moves in the opposite direction.
|
Linear tomography
|
|
|
Matrix of data that manipulates the values of gray levels, converting an image input value to a different output value.
|
Look-up table (LUT)
|
|
|
Ratio of the square of the diameter of the input phosphor to the square of the diameter of the output phosphor.
|
Minification gain
|
|
|
a. Grainy or uneven appearance of an image caused by an insufficient number of primary x-rays. b. Uniform signal produced by scattered x-rays.
|
Noise
|
|
|
X-rays produced in the anode but not at the focal spot
|
Off-focus radiation
|
|
|
Artifact produced by an improperly positioned radiographic tube—not by an improperly positioned grid
|
Off-level grid
|
|
|
Simple grid in which all lead grid strips are parallel.
|
Parallel grid
|
|
|
Active layer of the radiographic intensifying screen closest to the radiographic film.
|
Phosphor
|
|
|
Emission of visible light during and after stimulation
|
Phosphorescence
|
|
|
All planned and systematic actions necessary to provide adequate confidence that a facility, system, or administrative component will perform safely and satisfactorily in service to a patient. It includes scheduling, preparation, and promptness in examination or treatment, reporting of results, and quality control.
|
Quality assurance (QA)
|
|
|
All actions necessary to control and verify the performance of equipment; part of quality assurance.
|
Quality control (QC)
|
|
|
Device that converts the energy of the x-ray beam into visible light to increase the brightness of an x-ray image
|
Radiographic intensifying screen
|
|
|
Principle that states that optical density on a radiograph is proportional only to the total energy imparted to the radiographic film.
|
Reciprocity law
|
|
|
Ratio of primary radiation to scattered radiation transmitted through the grid.
|
Selectivity
|
|
|
Optical step wedge that is used to construct a characteristic curve
|
Sensitometer
|
|
|
Transformer in which the voltage is decreased from the primary side to the secondary side.
|
Step-up transformer
|
