Quiz 7: Radiography Testing

An excellent radiograph is obtained under given conditions of exposure with the film located at a distance of 914.4 mm (36 in.) from the target of the x-ray tube. If the film is now placed only 457.2 (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

The penetrating ability of an x-ray beam is governed by:

• a. kilovoltage

• b. time

• c. milliamperage

• d. source-to-film distance

Three liquids which are essential to process an exposed radiographic film properly are:

• a. stop bath, acetic acid and water

• b. developer, stop bath and H2O2

• c. developer, fixer and water

• d. acetic acid, fixer and stop bath

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

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:

• a. a reference plate

• b. a lead screen

• c. an image quality indicator (IQI)

• d. an illuminator

The radiation quality of a gamma ray source is:

• a. determined by the size of the focal spot

• b. determined by the isotope involved

• c. varied by the operator

• d. greater in Ir-192 than in Co-60

When referring to a 2T or 4T hole in the ASTM IQI, the T refers to the:

• a. part thickness

• b. plaque thickness

• c. time of exposure

• d. time for developing

Gamma radiation and x-radiation interact with matter and may be absorbed by:

• a. photoelectric absorption

• b. Compton scattering

• c. pair production

• d. all of the above

Low voltage x-ray tubes are generally fitted with windows made of:

• a. plastic

• b. beryllium

• c. glass

• d. lead

If it were necessary to radiograph a 177.8 mm (7 in.) thick steel product, which of the following gamma ray sources would most likely be used?

• a. Co-60

• b. Tm-170

• c. Ir-192

• d. Cs-137