When the speed of imaging systems doubles, for example, when changing from a 200-speed to a 400-speed system, the necessary patient radiation exposure is ______ by approximately ______.
reduced, 50%
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
Depending on the area of the body being examined with a fluoroscopic image intensification system, for adult patients, a range of ______ kVp is generally used
75 - 110
A radiographer uses a high-speed digital system with optimal technical exposure factors to obtain an AP radiograph of a 3-week old child's chest. To maximize reduction of radiation exposure to the patient following adequate immobilization, the radiographer should:
collimate the x-ray beam than the margins of the image receptor and shield the child's reproductive organs.
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
When a fluoroscopic image is electronically amplified by the use of an image intensification system, which of the following benefits results ?1. Increased image brightness2. Saving of time for the radiologist3. Patient dose reduction
1, 2, and 3
When settings are changed from one mA to a neighboring mA station, the most that linearity can vary is :
10%
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 light from the imaging plate that is changed into an electronic signal by a device called a
photomultiplier tube
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
The luminance of a collimator light is determined by measuring the concentration of light :
over a particular field of view
What is the purpose of radiographic beam filtration?
To increase beam hardness, thereby reducing patient skin dose and the dose to superficial tissues
Compared with the former material in the front of a cassette (aluminum or cardboard), the cassette front containing carbon fiber absorbs approximately ______ as much radiation, resulting in a __________ dose for the patient because ________ radiographic techniques are required to produce the recorded image.
half, lower, lower
The control panel, where technical exposure factors are selected and seen on indicators by the equipment operator, must be located
behind a suitable protective barrier that has a radiation-absorbent window that permits observation of the patient during any procedure.
In standard image intensification fluoroscopy, an x-ray beam half-value-layer (HVL) of 3 to 4.5 mm Al Eq is considered acceptable when peak kilovoltage (kVp) ranges from
80 - 100
Sharper size restriction of the radiographic beam is achieved when a cone or cylinder is
longer
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
Federal government specifications recommend a minimum total filtration of _______________ for stationary (fixed) fluoroscopic x-ray units operating above 70 kVp
2.5-mm aluminum equivalent
Current federal standards limit entrance skin exposure (ESE) rates of general-purpose intensified fluoroscopic units to a maximum of ______________ measured at tabletop with the image intensifier entrance surface at a prescribed 30 cm above
100 mGya/min
CR imaging has greater ____________ flexibility than conventional screen-film radiography
kilovoltage
Which of the following is not an x-ray beam limitation device
filter
Of the following procedures, which involve extended fluoroscopic time:1. Biliary drainage2. Stent and filter placement3. Urinary or biliary stone removal
1, 2, and 3
Digital radiography images can be accessed
at several workstations at the same time, making image viewing very convenient for physicians providing patient care.
Computed radiography, because of its higher exposure latitude, makes grid use on the pediatric population
less necessary than was previously believed
To visualize smaller and lower contrast objects during interventional procedures, high-level-control fluoroscopy (HLCF) uses exposure rates that are ____________ those normally used in routine fluoroscopy
higher than
When using digital fluoroscopy systems, making use of the last-image-hold (LIH) feature can
be an effective dose reduction technique