Test Bank for Patient Care in Radiography 9th Edition by Ehrlich.
Patient Care in Radiography: With an Introduction to Medical Imaging 9th Edition by Ruth - Ch. 1-22
Patient Care in Radiography: With an Introduction to Medical Imaging 9th Edition by Ruth - Ch. 1-22
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Test Bank: Patient Care in Radiography: With an Introduction to
Medical Imaging 9th Edition by Ruth - Ch. 1-22,
9780323353762, with Rationales
Exposure Time - ANSWER:is a measure of how long the exposure will continue and is measured in
units of seconds, fractions of seconds, or milliseconds.
What happens when there's an increase or decrease to exposure time - ANSWER:a longer exposure
time results in the production of more x-rays
Increased time= darker image
Decreased time= less radiation and a lighter image
Automatic Exposure Control (AEC) - ANSWER:these devices terminate the exposure when a specific
quantity of radiation has reached the IR
Milliamperage (mA) - ANSWER:is a measure of the current flow rate in the x-ray tube circuit. It
determines the number of electrons available to cross the tube and thus the rate at which x-rays are
produced.
Why a high mA setting? - ANSWER:Because it's used to shorten the needed exposure time when
motion during a longer exposure would likely cause blurring of the radiographic image
Milliampere-Seconds (mAs) - ANSWER:measurement of milliamperage multiplied by the exposure
time in seconds, which controls the total quantity of x-ray photons produced in the x-ray tube.
indicates the amount of radiation in the exposure
Kilovoltage (kVp) - ANSWER:measure of the potential difference across the x-ray tube. an increase in
kvp results a more penetrating x-ray beam and a greater degree of exposure to the IR, producing a
darker image.
kVp - ANSWER:determined the speed of electrons in the electron stream. determines the amount of
kinetic energy each electron has when it collides with the target
kVp energy - ANSWER:the energy is expressed by the wavelength of the photons. x-ray photons with
shorter wavelengths have more energy and are more penetrating than those with longer wavelengths
kVp settings for different body parts - ANSWER:50-60 kVp= usually for upper or lower extremities
(hand, wrist, foot, etc)
Spine= between 75 to 85 kVp
>100= chest radiography or for studies of the digestive tract
Source-to-Image Distance (SID) - ANSWER:the distance between the source of the x-rays (usually the
focal spot of the x-ray tube) and the image receptor
inverse square law - ANSWER:the relationship between radiation intensity and the SID: radiation
intensity is inversely proportional to the square of the SID
computed radiography - ANSWER:imaging plate that consists of photo-stimulable phosphors
digital radiography - ANSWER:does not use conventional equipment. they have radiation receptors
within the radiographic table , upright bucky or stand-alone DR receptors that transmit digital signals
directly to the computer system
, Exposure Index (EI) numbers - ANSWER:digital processing systems usually display an exposure
indicator number on the monitor. This number is monitored on the screen to ensure that exposures
are of diagnostic quality and are not excessive
Picture Achieving & Communications Systems (PACS) - ANSWER:the computer hardware and software
technology used to manage digital images in hospitals and healthcare facilities. provides archived for
the storage of images from all digital imagining modalities
Optical Density - ANSWER:The overall blackness of the image.
What is Optical Density influenced by? - ANSWER:In filmless radiographic systems, the radiographic
density of the image is mostly controlled by the computer; a change in mAs exposure factors will not
necessarily darken or lighten the image; however, if underexposed, a "grainy" appearing image will be
produced because of the lack of sufficient x-ray photons striking the IR.
-Meaning mAs can influence optical density
tissue density vs optical density - ANSWER:TD= refers to the mass density of anatomic parts. increase
in TD results in a lighter image
OD: increase in OD indicates the image is darker
Image contrast - ANSWER:the difference in the optical density of adjacent structures within the image
High-contrast image - ANSWER:black-and-white appearance. structures in the gray areas are easily
distinguished, but no details can be seen the very dark or very light portions of the image.
(few grays, few steps)
Low-contrast image - ANSWER:an overall gray appearance, and the structures tend to blend into one
another.
(many grays, many steps)
What is the primary contract control factor? - ANSWER:kVp
Other= nature of the subject, the characteristics of the IR, and the amount of scatter radiation
affecting the IR.
What is needed for a desired radiographic density - ANSWER:High kVp, low mAs
When higher contrast is desired... - ANSWER:the kVp is decreased. It will result in less penetration by
the x-ray beam, a beam of greater intensity is needed, and the mAs must be increased.
SID and OID - ANSWER:increasing the SID sharpens the image, whereas increasing OID reduces
sharpness.
*Increase SID and decrease OID!!
Distortion - ANSWER:refers to a variation in the size or shape of the image compared with the object
it represents.
Factors that affect magnification - ANSWER:OID and SID
Reason behind shape distortion - ANSWER:The result of unequal magnification of various parts of the
subject. Angulation of the x-ray beam, the IR, or the object in relation to the IR will cause some
degree of distortion.
How to avoid shape distortion? - ANSWER:when the plane of the object is parallel to the plane of the
IR and the central ray is perpendicular to it.
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