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RT Exposure - PartII

Review-Bushong Chptrs. 10,11,12, 13, 14

Question	Answer
Interaction involving incident x-ray interacting with outer-shell loosely bound electrons	Compton Effect or Scattering
Compton scattering reduces image __________	contrast
During fluroscopy the greatest source of scattered radiation	PATIENT
Compton or photoelectric increases with increasing kVp	Compton
Effect of atomic number of absorber on Compton scattering	No effect
As the mass density of absorber increases; there is increase or decrease in Compton	Increase
Inner-shell electron interaction and total absorption of incoming x-ray	Photoelectric
The probability of photoelctric effect and the atomic number of absorbing material	directly to the third power
As kVp increases the amount of photoelectric increases or decreases	decreases
As the mass density of patient body part increases the amount of photoelectric	proportional increase
using radiation and film to produce an image is known as _________ effect	photographic
T or F don't worry about placing your lead R or L marker on an image - just add later!	False - any lawyer can argue that you took the wrong side of body and added marker to correct
T or F Radiographic film has an expiration date	True
T or F Film should be stored in an upright position.	True
T or F Due to the ability to add any patient information to an image after processing don't worry about getting correct information	False - lawyers!
The active layer of film is the _______________	emulsion containing silver halide crystals
Radiographic film will LOSE or GAIN contrast if stored in temperatures above 68 degrees	loss of contrast and also too high developer temperature,radiation fog,increased shelf life
Too dry storage conditions or humidity below 40% results in ______ ________ artifacts	static electricity
Low contrast films produces images with ______________ (color?)	many shades of gray
High contrast film produces images with ______________________ (color?)	black-and-white
The ________ of a screen-film is its sensitivity to x-rays and light	Speed
An 800 screen-film combination requires more radiation than an 100 speed system. T or F	False
The range of acceptable exposure technique to produce an image is known as this	latitude
T or F Automatic processing is common in current imaging departments	False - laser printers
During the developing stage of film processing is when the _______ image to _________ image	latent to visible
The purpose of the fixer is this	clearing underexposed silve halide from film and hardening of film emulsion
Which stage of processing is associated with archival quality	fixer
Using an incorrect safelight may result in fogging of a film T or F	True
In addition to turning on the main switch of a processor what other step must be taken	turn on the water supply
T or F Daylight processors were the latest technology before digital processing	True
The purpose on an intensifying screen	convert incoming x-rays to light after interaction with screen's phosphor
The ________ is the active layer of the radiographic intensifying screen	phosphor
Term for matching of screen light wavelength or color with film sensitivity	Spectral matching
Exposure required without screens/ exposure with screens	Intensification Factor (IF)
Speckeled appearance on an image cause by increase in screen speed and too little mAs	image noise or quantum mottle
Emitting light(phosphor) in response to some outside stimulation	luminescence or fluorescence
Emitting light (phosphor) even after stimulation	phosphorescence
Other terms for phosphorescence	screen laf or afterglow
Definition of detective quantum efficiency (DQE)	Percentage of x-rays absorbed by image receptor
Definition of conversion efficiency (CE) of screens	amount of light emitted by screen phosphor for each x-ray absorbed
Grainy,mottled or splotchy image	quantum mottle
Ability to image small objects that have high subject contrast	spatial resolution
Ability to distinguish between and to image similar tissues.	contrast resolution
Faster(high) speed screens have more or less spatial resoultion	less
Spatial resolution may be measured in units of______________	line pairs per millimeter
The rigis holder that contains the radiographic film and intensifying screens	cassette
An increase in photoelctric effect results in Increase or Decrease in patient dose	increase because of photoelctric absorption
Increase kVp results in more _____________	scattered radiation
Scatter radiation Increases or Decreases as the field size of the x-ray beam increases	increases
Scatter radiation from not enough collimation will result in ________ contrast and ________	decreased contrast and increased film density
Increasing patient thickness results in greater scatter radiation; to minimize this effect use_____________________	compression paddle or compression belt or possible turn patient
State three examples of beam-restricting devices	variable aperture collimator, variable diaphragm and cones or cylinders
What is the purpose of a PBL	positive beam limiting device, type of automatic collimation and beam size is not larger than cassette size
A device used to reduce the amount of scatter radiation reaching the image receptor	grid
The grid is found between the ________ and the ____________	patient and image receptor
The ________ ratio grid ________ patient dose	high ratio increases dose or low ratio grid reduces
The formula to claculate grid ratio	grid ratio = h/D
The radiolucent material found between the grid strips	interspace material
The number of grid strips per centimeter is called grid ____________	frequency
the use of higher frequency grids result in having to use ____________ exposure technique and ________ radiation exposure	greater and greater
Specially designed grids having ratios of ___________ are used in mammography	4:1 or 5:1
Define nonhygrososcopic	doesn't absorb moisture
Interspace material	aluminum or plastic fiber
Grid strip material	lead
The major function of a grid	improve image contrast
k = image contrast with grid/image contrast without grid	contrast improvement factor
The contrast improvement factor is ________ for high-ratio grids	higher
B = patient dose with grid/patient dose without grid	Bucky Factor
When going from using no grid to using a 16:1 grid you need to increase the original mAs about _________ times	5- 6 times
The undesirable absorption of x-rays by the grid resulting in absence of optical density	grid cutoff
Grid 'cutoff" most common with __________ grids	parallel
This type of grid has strips running parallel to long and short axes of the grid	crossed
This type of grid has strips coincide with the divergence of the x-ray beam	focused
T or F High-ratio grids have less positioning latitude than low-ratio grids	True
A reason for grid cutoff when using a focused grid	wrong distance used
Moving grids are common in the imaging department	True or False
Appearance of cutoff when the grid is off-focus or upside-down	grid cut-off toward the edges
Grid ratios up to _____ are used for 90 kVp and under	8:1
When using no grid and then switching to a 16:1 grid you need to increase your kVp by ___________ kVp	30 - 40
Using grids in the air-gap technique results in _________ contrast and ________ scatter radiation	improved contrast and reduced scatter
T or F During the air gap technique radiation scatter is reduced because the air filters the low energy x-rays	False - air can't filter x-rays; the distance from patient to grid prevents x-rays from reaching the grid/film

Created by: fleury21 on 2011-02-13

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RT Exposure - PartII

Review-Bushong Chptrs. 10,11,12, 13, 14