para cargar 200 a 300 Flashcards
- Materials that are exposed to thermal neutron beams:
(A) must not be handled for at least 3 minutes after exposure has ceased.
(B) must be stored in a lead-lined room.
(C) may be radioactive after exposure to neutrons has ceased.
(D) should be monitored by means of a neutron counter.
(E) present no particular problems since they cannot be radioactive.
(C) may be radioactive after exposure to neutrons has ceased.
- Lead is:
(A) a good neutron shield.
(B) corroded by neutron exposures.
(C) a relatively poor neutron absorber.
(D) an efficient conversion screen.
(C) a relatively poor neutron absorber.
- If 2 mm (0.08 in.) of plastic attenuates a thermal neutron beam by a factor of 2 then 2 cm (0.8 in.) will attenuate it by approximately a factor of:
(A) 10.
(B) 20.
(C) 100.
(D) 200.
(E) 1 000.
(E) 1 000.
- Materials in common usage for moderation of fast-neutron sources include:
(A) aluminum magnesium and tin.
(B) water plastic paraffin and graphite.
(C) neon argon and xenon.
(D) tungsten cesium antimony and columbium.
(B) water plastic paraffin and graphite.
- The main reason for using neutron radiography in place of X-radiography is:
(A) a lower cost.
(B) higher resolution.
(C) the ability to image objects and materials not possible with X-rays.
(D) a simpler radiographic procedure required than X-radiography.
(C) the ability to image objects and materials not possible with X-rays.
- A photographic record produced by the passage of neutrons through a specimen onto a film is called:
(A) a fluoroscopic image.
(B) a radiograph.
(C) an isotopic reproduction.
(D) a track-etch photograph.
(B) a radiograph.
- Many of the absorption differences between neutrons and X-rays indicate that the two techniques:
(A) cause radiation problems.
(B) complement each other.
(C) can be used interchangeably.
(D) can both be used to image hydrogenous materials equally well.(E) are in no manner related.
(B) complement each other.
- The penetrating ability of a thermal neutron beam is governed by:
(A) attenuating characteristics of the material being penetrated.
(B) exposure time.
(C) source-to-film distance.
(D) all of the above.
(A) attenuating characteristics of the material being penetrated.
- The transfer exposure method is used because:
(A) it is not influenced by gamma radiation in the primary beam.
(B) it produces greater radiographic sensitivity than the direct exposure using gadolinium.
(C) it is faster than the direct exposure method.
(D) the screens used in this method emit only internal conversion electrons of about 70 keV.
(A) it is not influenced by gamma radiation in the primary beam.
- Higher resolution can be achieved in direct neutron radiography by:
(A) placing a lead intensifying screen between a gadolinium screen and film.
(B) increasing the L/D ratio of the collimation system.
(C) increasing the exposure time.
(D) increasing the distance between the object and the film cassette.
(B) increasing the L/D ratio of the collimation system.
- The primary advantage of using a Cf-252 source for neutron radiography is its:
(A) portability.
(B) low cost per unit neutron flux compared to other neutron radiographic sources.
(C) high resolution.
(D) long useful life.
(A) portability.
- Quality of the results from a neutron radiographic exposure is best determined by:
(A) reference standards.
(B) image quality indicators.
(C) neutron flux measurement.
(D) densitometer readings.
(B) image quality indicators.
- The radiographic image of flaws in the imaging screens can be separated from actual flaws in a part being radiographed by:
(A) producing a photographic copy of the original neutron radiograph using X-ray duplicating film.
(B) comparing a neutron radiograph of the parts to a blank neutron radiograph of the same imaging screen with no parts in place.
(C) increasing the exposure time of the radiograph.
(D) decreasing the temperature of the developer solution.
(B) comparing a neutron radiograph of the parts to a blank neutron radiograph of the same imaging screen with no parts in place.
- For inspection of radioactive objects or those that emit gamma radiation when bombarded with neutrons a preferable detection technique is the:
(A) direct exposure technique.
(B) transfer technique.
(C) isotopic reproduction technique.
(D) electrostatic-belt generator technique.
(E) lead screen technique.
(B) transfer technique.
- Neutron radiography is an excellent tool for determining:
(A) the coating thickness of aluminum oxide on anodized aluminum.
(B) the size of voids in thick steel castings.
(C) the integrity of thin plastic material within a steel housing.
(D) none of the above.
(C) the integrity of thin plastic material within a steel housing.
- Neutron radiography extends radiographic capability for detecting cracks in small cylinders of:
(A) aluminum.
(B) iron.
(C) magnesium.
(D) plutonium.
(E) bronze.
(D) plutonium.
- Which of the following is not a preferred application of neutron radiography?
(A) Detecting the presence or absence of explosive material contained within a metal device.
(B) Detecting the presence of water in the cells of stainless steel honeycomb.
(C) Detecting the proper alignment of a rubber seal in a small steel valve assembly.
(D) Detecting the presence of a lead rupture diaphragm in a small aluminum safety valve assembly.
(D) Detecting the presence of a lead rupture diaphragm in a small aluminum safety valve assembly.
- The penetrating ability of an X-ray beam is governed by:
(A) kilovoltage or wavelength.
(B) time.
(C) milliamperage.
(D) source-to-film distance.
(A) kilovoltage or wavelength.
- Two X-ray machines operating at the same nominal kilovoltage and milliamperage settings:
(A) will produce the same intensities and energies of radiation.
(B) will produce the same intensities but may produce different energies of radiation.
(C) will produce the same energies but may produce different intensities of radiation.
(D) may give not only different intensities but also different energies of radiation.
(D) may give not only different intensities but also different energies of radiation.
- Which of the following X-ray generators would produce the narrowest cone of X-radiation?
(A) 10 MeV.
(B) 15MeV.
(C) 25 MeV.
(D) 1 MeV.
(E) Co-60.
(C) 25 MeV.
- Short wavelength electromagnetic radiation produced during the disintegration of nuclei of radioactive substances is called:
(A) X-radiation.
(B) gamma radiation.
(C) scatter radiation.
(D) backscatter radiation.
(E) beta radiation.
(B) gamma radiation.
- Almost all gamma radiography is performed with:
(A) natural isotopes.
(B) artificially produced isotopes.
(C) Radium.
(D) Tm-170.
(E) Co-60.
(B) artificially produced isotopes.
- The energy of gamma rays is expressed by which of the following units of measurement?
(A) Curie.
(B) Roentgen.
(C) half-life.
(D) Kiloelectron volts (keV) or Millions of electron volts (MeV).
(E) None of the above.
(D) K iloelectron volts (keV) or Millions of electron volts (MeV).
- Of the following the source providing the most penetrating radiation is:
(A) electrons from IR-192.
(B) Co-60.
(C) 220 kVp X-ray tube.
(D) 15 MeV betatron.
(D) 15 MeV betatron.
- Common sources of neutrons for neutron radiography are:
(A) electron linear accelerators.
(B) isotopes of Cobalt (Co-60 is one).
(C) nuclear reactors.
(D) betatrons.
(E) radioactive isotopes of iodine.
(C) nuclear reactors.
- The difference between the densities of two areas of a radiograph is called:
(A) radiographic contrast.
(B) subject contrast.
(C) film contrast.
(D) definition.
(E) opacity.
(A) radiographic contrast.
- The fact that gases when bombarded by radiation ionize and become electrical conductors makes them useful in:
(A) X-ray transformers.
(B) X-ray tubes.
(C) masks.
(D) radiation detection equipment.
(E) fluoroscopes.
(D) radiation detection equipment.
- The reason exposure time must be increased by a factor of four when the source-to-film distance is doubled is that the:
(A) intensity of radiation decreases at an exponential rate when the source-to-film distance is increased.
(B) energy of radiation is inversely proportional to the square root of the distance from the source to the film.
(C) intensity of radiation is inversely proportional to the square of the distance from the source to the film.
(D) scattered radiation effect is greater as the source-to-film distance increases.
(C) intensity of radiation is inversely proportional to the square of the distance from the source to the film.
- The most important factor in X-ray absorption of a specimen is:
(A) the thickness of the specimen.
(B) the density of the specimen.
(C) the atomic number of the material.
(D) Young’s Modulus of the material.
(E) the volume of the material.
(C) the atomic number of the materiai.
- Which of the following is the probable early effect of a 25 REM radiation dose to the whole body?
(A) No physical effect.
(B) Blood changes no serious injury.
(C) injury possible disability.
(D) Fatal to 50 percent of those receiving that dose.
(B) Blood changes no serious injury.
- Exposure to small doses of X-rays or gamma rays:
(A) have a cumulative effect that must be considered when monitoring for maximum permissible dose.
(B) are beneficial because they serve to build an immunity in humans to radiation poisoning.
(C) will have no effect on human beings.
(D) will have only a short-term effect on human tissues.
(A) have a cumulative effect that must be considered when monitoring for maximum permissible dose.
- Which of the following technique variables is most commonly used to adjust subject contrast?
(A) Source-to-film distance.
(B) Milliamperage.
(C) Kilovoltage.
(D) Focal spot size.
(E) All of the above.
(C) Kilovoltage.
- A basic difference between a radiograph and a fluoroscopic image is that:
(A) the fluoroscopic image is more sensitive.
(B) the fluoroscopic image is positive whereas the radiographic image is negative.
(C) the fluoroscopic image is brighter.
(D) there is no basic difference between the two.
(B) the fluoroscopic image is positive whereas the radiographic image is negative.
- Thin sheets of lead foil in intimate contact with X-ray film during exposure increase film density because they:
(A) fluoresce and emit visible light which helps expose the film.
(B) absorb the scattered radiation.
(C) prevent backscattered radiation from fogging the film.
(D) emit electrons when exposure to X and gamma radiation which helps to darken the film.
(E) absorb low energy components from the primary beam.
(D) emit electrons when exposure to X and gamma radiation which helps to darken the film.
- When viewing a radiograph an image of the back of the cassette superimposed on the image of the specimen is noted. This is most likely due to:
(A) undercut.
(B) overexposure.
(C) X-ray intensity being too high.
(D) backscattered radiation.
(D) backscattered radiation.
- A penetrameter is used to measure the:
(A) size of discontinuities in a part.
(B) density of the film.
(C) amount of film contrast.
(D) quality of the radiographic technique.
(E) amount of radiation that penetrates the test object.
(D) qual ity of the radiographic techniq ue.
- In film radiography 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.
(E) on the back side of the film.
(B) on the source side of the test object.
- At voltages above 400 kV the use of lead to provide protection may present serious structural problems. If this should be a serious problem which of the following materials would most likely be used as a substitute?
(A) Aluminum.
(B) Concrete.
(C) Steel.
(D) Boron.
(E) Polyethylene.
(B) Concrete.
- A distinctive characteristic of high voltage radiography is that:
(A) it results in comparatively high subject contrast.
(B) it results in comparatively high radiographic contrast.
(C) it is appiicabie to comparatively thick or highly absorbing specimens.
(D) all of the above are distinctive characteristics of high voltage radiography.
(C) it is appiicabie to comparatively thick or highly absorbing specimens.
- Given the radiographic equivalency factors of 1.4 for Inconel and 1.0 for 304 stainless steel what is the approximate equivalent thickness of inconel to produce the same exposure as a 0.15 in. thickness of 304 stainless steel?
(A) 3 mm (0.11 in.)
(B) 9 mm (0.35 in.)
(C) 18mm (0.7 in.)
(D) 36 mm (1.4 in.)
(A) 3 mm (0.11 in.)