ESTUDYR
ASNT RT I EXAM 120 QUESTIONS AND CORRECT DETAILED
ANSWERS UPDATE ALREADY A GRADE
Although there may be other reasons for using calcium tungstate screens in industrial
radiography, they are most usually used to:
A. Improve image contrast
B. Reduce film grain
C. Decrease exposure time (Correct)
D. Increase film resolution
Rationale: Calcium tungstate intensifying screens emit visible light that boosts film exposure,
allowing shorter exposure times.
In film radiography, penetrameters (penetrameters) are usually placed:
A. On the film side of the test object
B. On the source side of the test object (Correct)
C. Between film and cassette back
D. On the developer tray
Rationale: Penetrameters are placed on the source side to simulate a known thickness and
check technique.
The penetrating ability of an x-ray beam is primarily governed by:
A. Milliamperage (mA)
B. Kilovoltage (kV) (Correct)
C. Exposure time (s)
D. Focal spot size
Rationale: kV controls photon energy and thus beam penetrability.
Cobalt-60 used in nondestructive testing emits:
A. X-rays
B. Gamma rays (Correct)
C. Beta particles
D. Neutrons
Rationale: Co-60 is a gamma emitter used in industrial radiography.
A densitometer is an instrument for measuring:
A. Film thickness
B. Film density (Correct)
C. Radiation dose rate
,ESTUDYR
D. Grain size
Rationale: Densitometers quantify optical density on processed film.
Three liquids essential to properly process exposed film are:
A. Developer, fixer, and solvent
B. Fixer, water, and bleach
C. Developer, fixer, and water (Correct)
D. Developer, hardener, and solvent
Rationale: Standard manual processing uses developer, fixer, and thorough washing with
water.
The two most common causes for excessively high-density radiographs are:
A. Overdevelopment and underexposure
B. Overexposure and underdevelopment (Correct)
C. Low kV and small focal spot
D. Excessive filtration and short SFD
Rationale: Too much exposure or insufficient development control produce very dark films.
The time required for one-half of the atoms in a radioactive sample to disintegrate is called:
A. Decay constant
B. Half-life (Correct)
C. Activity
D. Curie
Rationale: Half-life is the standard term for radioactive decay half-time.
What does R/h refer to when speaking of intensity?
A. Rads per hour
B. Roentgens per hour (Correct)
C. Rems per hour
D. Röntgen-equivalents per hour
Rationale: R/h is an older unit indicating exposure rate in Roentgens per hour.
The ability to detect a small discontinuity or flaw is called:
A. Resolution
B. Radiographic sensitivity (Correct)
C. Contrast scale
D. DQE (detective quantum efficiency)
Rationale: Radiographic sensitivity describes the minimum detectable flaw size.
Movement, geometry, and screen contact are three factors that affect radiographic:
A. Contrast
, ESTUDYR
B. Density
C. Unsharpness (Correct)
D. Graininess
Rationale: These factors blur the recorded image and increase unsharpness.
The difference between the densities of two areas of a radiograph is called:
A. Latitude
B. Radiographic contrast (Correct)
C. Definition
D. Noise
Rationale: Contrast is the optical density difference that makes features distinguishable.
The most widely used unit for measuring rate of decay (activity) of a gamma source
historically is the:
A. Becquerel
B. Curie (Correct)
C. Gray
D. Sievert
Rationale: Curie is the traditional activity unit (Ci); SI unit is Becquerel (Bq).
Exposure to x-rays or gamma rays will have what effect on the body?
A. No cumulative effect with repeated low doses
B. It may have a cumulative effect which must be considered (Correct)
C. Only acute effects matter clinically
D. Radiation is harmless below any threshold
Rationale: Ionizing radiation can produce cumulative biological effects over time.
Which whole-body dose would be dangerous, if not fatal, if applied in a short period?
A. 1.5–15 R
B. 25–70 R
C. 200–800 R (Correct)
D. All of the above are fatal
Rationale: Acute whole-body doses in the hundreds of R (≈Gy) are potentially lethal.
When doing gamma-ray radiography with high-intensity emitters, sources are best handled:
A. With gloved hands and short exposure
B. By remote handling equipment (Correct)
C. Manually if shielded with lead aprons
D. By hand while wearing dosimeters only
Rationale: Remote handling reduces dose to personnel with high-activity sources.
ASNT RT I EXAM 120 QUESTIONS AND CORRECT DETAILED
ANSWERS UPDATE ALREADY A GRADE
Although there may be other reasons for using calcium tungstate screens in industrial
radiography, they are most usually used to:
A. Improve image contrast
B. Reduce film grain
C. Decrease exposure time (Correct)
D. Increase film resolution
Rationale: Calcium tungstate intensifying screens emit visible light that boosts film exposure,
allowing shorter exposure times.
In film radiography, penetrameters (penetrameters) are usually placed:
A. On the film side of the test object
B. On the source side of the test object (Correct)
C. Between film and cassette back
D. On the developer tray
Rationale: Penetrameters are placed on the source side to simulate a known thickness and
check technique.
The penetrating ability of an x-ray beam is primarily governed by:
A. Milliamperage (mA)
B. Kilovoltage (kV) (Correct)
C. Exposure time (s)
D. Focal spot size
Rationale: kV controls photon energy and thus beam penetrability.
Cobalt-60 used in nondestructive testing emits:
A. X-rays
B. Gamma rays (Correct)
C. Beta particles
D. Neutrons
Rationale: Co-60 is a gamma emitter used in industrial radiography.
A densitometer is an instrument for measuring:
A. Film thickness
B. Film density (Correct)
C. Radiation dose rate
,ESTUDYR
D. Grain size
Rationale: Densitometers quantify optical density on processed film.
Three liquids essential to properly process exposed film are:
A. Developer, fixer, and solvent
B. Fixer, water, and bleach
C. Developer, fixer, and water (Correct)
D. Developer, hardener, and solvent
Rationale: Standard manual processing uses developer, fixer, and thorough washing with
water.
The two most common causes for excessively high-density radiographs are:
A. Overdevelopment and underexposure
B. Overexposure and underdevelopment (Correct)
C. Low kV and small focal spot
D. Excessive filtration and short SFD
Rationale: Too much exposure or insufficient development control produce very dark films.
The time required for one-half of the atoms in a radioactive sample to disintegrate is called:
A. Decay constant
B. Half-life (Correct)
C. Activity
D. Curie
Rationale: Half-life is the standard term for radioactive decay half-time.
What does R/h refer to when speaking of intensity?
A. Rads per hour
B. Roentgens per hour (Correct)
C. Rems per hour
D. Röntgen-equivalents per hour
Rationale: R/h is an older unit indicating exposure rate in Roentgens per hour.
The ability to detect a small discontinuity or flaw is called:
A. Resolution
B. Radiographic sensitivity (Correct)
C. Contrast scale
D. DQE (detective quantum efficiency)
Rationale: Radiographic sensitivity describes the minimum detectable flaw size.
Movement, geometry, and screen contact are three factors that affect radiographic:
A. Contrast
, ESTUDYR
B. Density
C. Unsharpness (Correct)
D. Graininess
Rationale: These factors blur the recorded image and increase unsharpness.
The difference between the densities of two areas of a radiograph is called:
A. Latitude
B. Radiographic contrast (Correct)
C. Definition
D. Noise
Rationale: Contrast is the optical density difference that makes features distinguishable.
The most widely used unit for measuring rate of decay (activity) of a gamma source
historically is the:
A. Becquerel
B. Curie (Correct)
C. Gray
D. Sievert
Rationale: Curie is the traditional activity unit (Ci); SI unit is Becquerel (Bq).
Exposure to x-rays or gamma rays will have what effect on the body?
A. No cumulative effect with repeated low doses
B. It may have a cumulative effect which must be considered (Correct)
C. Only acute effects matter clinically
D. Radiation is harmless below any threshold
Rationale: Ionizing radiation can produce cumulative biological effects over time.
Which whole-body dose would be dangerous, if not fatal, if applied in a short period?
A. 1.5–15 R
B. 25–70 R
C. 200–800 R (Correct)
D. All of the above are fatal
Rationale: Acute whole-body doses in the hundreds of R (≈Gy) are potentially lethal.
When doing gamma-ray radiography with high-intensity emitters, sources are best handled:
A. With gloved hands and short exposure
B. By remote handling equipment (Correct)
C. Manually if shielded with lead aprons
D. By hand while wearing dosimeters only
Rationale: Remote handling reduces dose to personnel with high-activity sources.
