RT / X-ray Level I Flashcards
Although there may be other reasons for using calcium tungstate screens in industrial radiography, they are most often used to:
a. improve definition and resolution in radiographic images
b. improve contrast in radiographic images
c. decrease exposure time
d. make films respond to multimillion volt radiation
c. decrease exposure time
An excellent radiograph is obtained under given conditions of exposure with the film located at a distance of 36 in. from the target of the X-ray tube. If the film is now placed only 18 in. from the target, and all exposure conditions except time are held constant, the new exposure time will be:
a. unchanged
b. longer by approximately 80%
c. shorter by approximately 55%
d. only about 25% as long as the original exposure time
d. only about 25% as long as the original exposure time
An excellent radiograph is obtained under given exposure conditions with a tube current of 5 mA and an exposure time of 12 min. If other conditions are not changed, what exposure time would be required if the X-ray tube current could be raised to 10 mA?
a. 24 min
b. 12 min
c. 6 min
d. 3 min
c. 6 min
In film radiography, image quality indicators (penetrameters) are usually placed:
a. between the intensifying screen and the film
b. on the source side of the test object
c. on the film side of the test object
d. between the operator and the radiation source
b. on the source side of the test object
When radiographing to the 2-2T quality level, an ASTM image quality indicator (IQI) for 0.5 in. thick 2024 aluminum alloy has a thickness of:
0.010 in.
The penetrating ability of an X-ray beam is governed by:
a. kilovoltage
b. time
c. milliamperage
d. source-to-film distance
a. kilovoltage
Co-60 used in nondestructive testing emits:
gamma rays
A densitometer is an instrument for measuring:
film density
Three liquids which are essential to process an exposed film properly are:
developer, fixer and water
The two most common causes for excessively high density radiographs are:
overexposure and overdevelopment
The time required for one-half of the atoms in a particular sample of radioactive material to disintegrate is called:
a half-life
What does the term R/h refer to?
roentgen per hour
The ability to detect a small detail is called radiographic:
sensitivity
The difference between the densities of two areas of a radiograph is called:
a. radiographic contrast
b. subject contrast
c. film contrast
d. definition
a. radiographic contrast
The unit of measurement used for the output of a gamma ray source is the:
becquerel (curie)
Exposure to X-rays or gamma rays:
a. may have a cumulative effect which must be considered
b. will be beneficial since they build up an immunity to radiation poisoning
c. will have no effect on human beings
d. will have only a short-term effect on human tissues
a. may have a cumulative effect which must be considered
Which dose would be dangerous, if not fatal, if applied to the entire body in a short period of time?
a. 15-150 mSv (1.5-15 R)
b. 250-700 mSv (25-70 R)
c. 5000-8000 mSv (500-800 R)
d. all of the above doses would most likely be fatal
c. 5000-8000 mSv (500-800 R)
When doing gamma ray radiography with high-intensity emitters, the sources are best handled:
by remote handling equipment
If a film is placed in a developer solution and allowed to develop without any agitation:
a. the radiograph may not show proper contrast
b. it will be impossible to fix the radiographic permanently
c. there will be a general “fogging” condition over the entire radiograph
d. uneven development or streaking could occur
d. uneven development or streaking could occur
The selection of the proper type of film to be used for the X-ray examination of a particular part depends on:
a. the thickness of the part
b. the material of the specimen
c. the voltage range of the available X-ray machine
d. all of the above
d. all of the above
A Co-60 source has a half-life of:
5.27 years
X-ray tube current is controlled by:
a. the current passing through the filament
b. the distance from the cathode to the anode
c. the type of material used in the target
d. the voltage and waveform applied to the X-ray tube
a. the current passing through the filament
Lead foil in direct contact with X-ray film:
a. intensifies the scatter radiation more than the primary radiation
b. decreases the contrast of the radiographic image
c. intensifies the primary radiation more than the scatter radiation
d. should not be used when gamma rays are emitted by the source of radiation
c. intensifies the primary radiation more than the scatter radiation
Lead intensifying screens are usually mounted in pairs in rigid holders called:
cassettes
In order to decrease geometric unsharpness:
a. radiation should proceed from as small a focal spot as other considerations will allow
b. radiation should proceed from as large a focal spot as other considerations will allow
c. the film should be as far as possible from the object being radiographed
d. the distance from the anode to the material examined should be as small as is practical
a. radiation should proceed from as small a focal spot as other considerations will allow
As the kilovoltage applied to the X-ray tube is raised:
a. X-rays of longer wavelength and more penetrating power are produced
b. X-rays of shorter wavelength and more penetrating power are produced
c. X-rays of shorter wavelength and less penetrating power are produced
d. X-rays of longer wavelength and less penetrating power are produced
b. X-rays of shorter wavelength and more penetrating power are produced
In order to increase the intensity of X-radiation:
a. the tube current should be increased
b. the tube current should be decreased
c. the test specimen should be moved farther from the film
d. a lower kilovoltage should be applied to the tube
a. the tube current should be increased
Primary radiation which strikes a film holder or cassette through a thin portion of the specimen will cause scattering into the shadows of the adjacent thicker portions producing an effect called:
a. radiation imaging
b. spotting
c. undercut
d. unsharpness
c. undercut
Scattered radiation caused by any material, such as a wall or floor, on the film side of the specimen is referred to as:
backscattered radiation
Which of the following materials is suitable for use in containers used to mix processing solutions?
stainless steel
Of the following, which would be especially sensitive to injury by excessive exposure to X-rays or gamma rays?
a. blood
b. lens of the eye
c. internal organs
d. all of the above
d. all of the above
Film overexposure from X-ray radiography may be caused by:
a. the direct beam from the X-ray tube target
b. scatter radiation arising from the objects in the direct beam
c. residual radiation that exists for the first few minutes after X-ray machine has been returned to the “off” position
d. both a and b may be causes
d. both a and b may be causes
A general rule often employed for determining the kilovoltage to be used when X-raying a part is that:
a. the kilovoltage should be as high as other factors will permit
b. the kilovoltage should be as low as other factors will permit
c. the kilovoltage is always a fixed value and cannot be changed
d. the kilovoltage is not an important variable and can be changed over a wide range without affecting the radiograph
b. the kilovoltage should be as low as other factors will permit
If a piece of lead 0.5 in. thick is placed in the path of a beam of radiation emanating from Co-60, it will reduce the dose rate at a given location by:
a. one-third
b. one-quarter
c. one-half
d. three-quarters
c. one-half
Excessive exposure of film to light prior to development of the film will most likely result in:
a foggy film
Reticulation resulting in a puckered or net-like film surface is probably caused by:
a. crimping film after exposure
b. sudden extreme temperature change while processing in the developer
c. water or developer on unprocessed film
d. excessive object-to-film distance
b. sudden extreme temperature change while processing in the developer
Frilling or loosening of the emulsion from the base of the film is most likely caused by:
a. water or developer on unprocessed film
b. low temperature of processing solutions
c. developer solution contamination
d. warm or exhausted fixer solution
d. warm or exhausted fixer solution
If an exposure time of 60 s was necessary using a 4 ft source-to-film distance for a particular exposure, what time would be necessary if a 2 ft source-to-film distance is used and all other variables remain the same?
15 s
One of the general rules concerning the application of geometric principles of shadow formation to radiography is:
a. the X-rays should proceed from as large a focal spot as other considerations will allow
b. the film should be as far as possible from the object being radiographed
c. the distance between the anode and the material examined should always be as great as possible
d. all of the above
c. the distance between the anode and the material examined should always be as great as possible
As a check on the adequacy of the radiographic technique, it is customary to place a standard test piece on the source side of the specimen. This standard test piece is called:
an image quality indicator (IQI)
An IQI is used to indicate the:
a. size of discontinuity in a part
b. density of the film
c. amount of film contrast
d. sensitivity of the radiographic technique
d. sensitivity of the radiographic technique