Ch11 Final Flashcards
In the event that a pregnant patient is inadvertently irradiated:
the radiologic physicist should perform the calculations necessary to determine fetal dose.
When the speed of screen-film systems doubles, for example, when changing from a 200-speed to a 400-speed system, patient radiation exposure is ______ by approximately ______.
reduced, 50%
Digital radiography images can be accessed:
at several workstations at the same time, making image viewing very convenient for physicians providing patient care.
When obtaining a dorsoplantar projection of a foot, which of the following types of filters should be used to provide a greater uniform density of the anatomy?
Wedge filter
When an exposed computed radiography imaging plate is ready to be processed, an imaging reading unit is used to scan the photostimulable phosphor imaging plate with a helium–neon laser beam. This process results in the emission of violet light that is changed into an electronic signal by a device called a:
photomultiplier tube.
Of the following procedures, which involve extended fluoroscopic time?
1. Biliary drainage
2. Stent and filter placement
3. Urinary or biliary stone removal
1, 2, and 3
According to the American College of Radiology (ACR), abdominal radiologic examinations that have been requested after full consideration of the clinical status of a patient, including the possibility of pregnancy, need:
not to be postponed or selectively scheduled.
During a fluoroscopic examination, a resettable cumulative timing device times the x-ray beam-on time and sounds an audible alarm or temporarily interrupts the exposure after the fluoroscope has been activated for what length of time?
. 5 minutes
________________________ are the sensing devices most often used to measure skin dose directly.
Thermoluminescent dosimeters
Federal government specifications recommend a minimum total filtration of _______________ for stationary (fixed) fluoroscopic x-ray units operating above 70 kVp.
Correcta. 2.5-mm aluminum equivalent
When a fluoroscopic image is electronically amplified by the use of an image intensification system, which of the following benefits results?
1. Increased image brightness
2. Saving of time for the radiologist
3. Patient dose reduction
123
Specific area shielding may be selectively used during some x-ray procedures to protect which of the following?
1. Lens of the eye
2. Breast
3. Extremities
12
Which of the following are considered to be benefits of an aggressive repeat analysis program?
1. Increased awareness among staff and student radiographers of the need to produce optimal quality recorded images
2. Radiographers generally become more careful in producing their images because they are aware that the images are being reviewed
3. When the repeat analysis program identifies problems or concerns, in-service education programs covering these specific topics may be designed for imaging personnel
123
Any image that must be performed more than once because of human or mechanical error during the production of the initial image is known as a repeat image. What effect does a repeat image have on the radiation dose received by the patient?
The patient’s skin and possibly the gonads receive a double radiation dose
When settings are changed from one mA to a neighboring mA station, the most that linearity can vary is:
10%
When performing a mobile fluoroscopic procedure, to reduce the radiation exposure to the patient, the radiographer must use a minimal source-skin distance of:
30 cm
In standard image intensification fluoroscopy, an x-ray beam half-value-layer (HVL) of 3 to 4.5 mm aluminum is considered acceptable when peak kilovoltage ranges from
80 to 100
The genetically significant dose (GSD) for the population of the United States is about:
0.20 mSv
When using digital fluoroscopy systems, making use of the last-image-hold feature can:
be an effective dose reduction technique
Which of the following types of gonadal shielding provides the best protection for a male patient when AP, oblique, and lateral projections are obtained?
Shaped contact shield containing 1 mm of lead
Which of the following is not an x-ray beam limitation device?
Filter
Because most medical procedures result in fetal exposures
less than 0.01 Gy, the risk of abnormality is small.
When automatic exposure control (AEC) is not used, then to ensure uniform selection of technical x-ray exposure factors, efficient imaging departments:
use standardized technique charts for each x-ray unit.
What is the purpose of radiographic beam filtration?
To increase beam hardness, thereby reducing patient skin dose and the dose to superficial tissues
Which of the following must always be the first step in protection of the reproductive organs?
Adequate and precise collimation of the radiographic beam to include only the anatomy of interest
If a child is placed in a CT scanner and adult protocols are used:
the child will receive a higher dose than the adult.
Which of the following materials is commonly used in the tabletop of a radiographic examination table to make the tabletop as radiolucent as possible so that it will absorb only a minimal amount of radiation, thereby reducing the patient’s radiation dose?
Carbon fiber material
The radiation dose absorbed by an organ such as bone marrow:
cannot be measured by a direct method; it can only be estimated
During mammography, axillary projections should be done only on request of the:
radiologist
During a radiographic examination, which of the following combinations of technical exposure factors and filtration reduce patient radiation dose?
Higher kVp, lower mAs, increased filtration
