VERIFIED RESPOSES
low voltage x-ray tubes are generally fitted with windows made of: - answer-beryllium
a monochromatic x-ray beam is: - answer-a beam consisting of a single wavelength
the general method of producing x-rays involves the sudden deceleration of high
velocity electrons in a solid body called a: - answer-target
if it were necessary to radiograph a 7" thick steel product, which gamma ray source
would most likely be used? - answer-co-60
a co-60 gamma source has an approximate practical thickness limit of: - answer-9" of
steel or its equivalent
the absorption of gamma rays from a given source when passing through matter
depends on the: - answer-atomic number, density, and thickness of the matter
the fact that gases, when bombarded by radiation ionize and become electrical
conductors make them useful in: - answer-radiation detection equipment
the velocity of electrons striking the target in an x-ray tube is a function of the: - answer-
voltage difference between the cathode and anode
the uneven distribution of developed grains within the emulsion of a processed x-ray
film causes the subjective impression of: - answer-graininess
the gamma ray intensity at 1 ft from a 1 Ci source of radioactive co-60 is nearest to: -
answer-15 R/h
the focal spot in an x-ray tube: - answer-should be as small as possible without unduly
shortening the life of the tube
in an x-ray tube, the filament and focusing cup are the two essential parts of the: -
answer-cathode
the quantity of radiation which will produce, by means of ionization, one electrostatic
unit of electricity in 0.001293 g of dry air is known as a: - answer-Roentgen
the specific activity of an isotopic source is usually measured in: - answer-curies per
gram (Ci/g)
which isotope has the longest half-life? - answer-Cs- 137
, the primary form of energy conversion when electrons strike a target in an x-ray tube
results in the production of: - answer-heat
the slope of a straight line joining two points of specified densities on a characteristic
curve of a film is known as the: - answer-average gradient
an x-ray film having wide latitude also has, by definition: - answer-low contrast
the purpose of circulating oil in some types of x-ray tubes is to: - answer-dissipate heat
an x-ray tube with a small focal spot is considered better than one with a large focal
spot when it is desired to obtain: - answer-better definition
one method of reducing radiographic contrast is to: - answer-decrease the wavelength
of the radiation used
thin sheets of lead foil in intimate contact with x-ray film during exposure increases film
density because they: - answer-emit electrons when exposed to x- and gamma radiation
which help darken the film
x-ray tubes are often closed in a shockproof casing in order to: - answer-protect the
operator from high- voltage shock
an x-ray tube is rated for a maximum of 250 kVp. this tube may be operated at a
maximum of: - answer-250,000 V peak voltage
a voltage selector consisting of an iron core transformer with a single winding having a
series of taps at various points on the winding is called: - answer-an autotransformer
in x-ray radiography, alternating current must be changed to pulsating direct current in
order to satisfy the need for unidirectional current. this change may be accomplished by:
- answer-cathodes
value tubes are used in x-ray equipment to: - answer-provide cessary rectification
when sharp, black, bird- foot shaped marks which are known not to correspond with any
discontinuities appear at random on radiographs, they are probably caused by: -
answer-static charges caused by friction
the adjustment of tube current in conventional x-ray tube circuits is made by: - answer-
adjusting the filament heating current
in comparison with lower-voltage radiographs, high- energy radiographs show: -
answer-greater latitude