RT Level III questions with verified answers
0.2 in Ans✓✓✓ Given the linear attenuation coefficient for 0.6 MeV
photons passing through lead is 1.36/cm, what is the half value layer
thickness?
a. 0.1 cm
b. 0.1 in
c. 0.2 in
d. 1 cm
1 Ans✓✓✓ The imperial unit of radiation, the curie, is 3.7 x 10^10
disintegrations per second. How many disintegrations per second is the
SI unit, the becquerel?
a. 1000
b. 100
c. 10
d. 1
1.3 Ans✓✓✓ In general, when using the composite film viewing
technique (super imposed), each film should have a minimum density of:
a. 1.3
b. 1.5
c. 1.8
d. 2.0
,1.39 Ans✓✓✓ If the incident light intensity on a film is 30 units, and
the measured transmitted light intensity is 1.20 units, what would the
film density be?
(Use the formula: D = log (Io / It) (Io = Incident Light, It = Transmitted
Light)
a. 1.39
b. 2.3
c. 3.2
d. 18.5
1/16 Ans✓✓✓ An occupancy factor commonly used for design
purposes of uncontrolled sidewalk areas is:
a. 1/4
b. 1/5
c. 1/16
d. 1
10CFR20 Ans✓✓✓ Specific areas of the Code of Federal Regulations
used frequently by radiography licensees are:
a. 10CFR20
b. 10CFR40
c. 10CFR50
d. 10CFR70
,150 mR/hr Ans✓✓✓ A survey instrument is to be calibrated using a 3.4
Ci Co-60 source. It is desired to calibrate the 100 to 1000 mR/hr range
of the instrument at +/- 20% at two locations on the range. The two
locations are at the lower limit plus 15% and the upper limit minus 15%
of the range at that point. If the instrument response was +30% of the
required lower level reading, it would read approximately:
a. 325 mR/hr
b. 150 mR/hr
c. 111 mR/hr
d. 195 mR/hr
2.96 inches Ans✓✓✓ A material with a 9.83 inch Tenth-Value Layer,
has a Half-Value Layer of:
a. 0.983 inches
b. 2.96 inches
c. 3.24 inches
d. 4.92 inches
20.6 ft Ans✓✓✓ A survey instrument is to be calibrated using a 3.4 Ci
Co-60 source. It is desired to calibrate the 100 to 1000 mR/hr range of
the instrument at +/- 20% at two locations on the range. The two
locations are at the lower limit plus 15% and the upper limit minus 15%
of the range at that point. What is the distance from the calibration
source to the instrument detector to obtain the calculated intensity
required at the lower limit check in the above situation?
a. 61.9 ft
b. 20.6 ft
, c. 13.2 ft
d. 39.6 ft
20% Ans✓✓✓ When radiographing a steel specimen 0.75 inches thick
with 275 kV peak X-rays, the use of a copper filter that is ___ of the
specimen thickness is recommended (if more latitude is necessary)
a. 20%
b. 10%
c. 4%
d. 15%
34 eV Ans✓✓✓ The minimum amount of energy required to produce
an ion pair in air is approximately:
a. 100 eV
b. 68 keV
c. 0.510 MeV
d. 34 eV
6.25% Ans✓✓✓ After 4 half lives, what percentage of a radioisotope's
life remains?
a. 25%
b. 12.5%
c. 6.25%
d. 3.12%
0.2 in Ans✓✓✓ Given the linear attenuation coefficient for 0.6 MeV
photons passing through lead is 1.36/cm, what is the half value layer
thickness?
a. 0.1 cm
b. 0.1 in
c. 0.2 in
d. 1 cm
1 Ans✓✓✓ The imperial unit of radiation, the curie, is 3.7 x 10^10
disintegrations per second. How many disintegrations per second is the
SI unit, the becquerel?
a. 1000
b. 100
c. 10
d. 1
1.3 Ans✓✓✓ In general, when using the composite film viewing
technique (super imposed), each film should have a minimum density of:
a. 1.3
b. 1.5
c. 1.8
d. 2.0
,1.39 Ans✓✓✓ If the incident light intensity on a film is 30 units, and
the measured transmitted light intensity is 1.20 units, what would the
film density be?
(Use the formula: D = log (Io / It) (Io = Incident Light, It = Transmitted
Light)
a. 1.39
b. 2.3
c. 3.2
d. 18.5
1/16 Ans✓✓✓ An occupancy factor commonly used for design
purposes of uncontrolled sidewalk areas is:
a. 1/4
b. 1/5
c. 1/16
d. 1
10CFR20 Ans✓✓✓ Specific areas of the Code of Federal Regulations
used frequently by radiography licensees are:
a. 10CFR20
b. 10CFR40
c. 10CFR50
d. 10CFR70
,150 mR/hr Ans✓✓✓ A survey instrument is to be calibrated using a 3.4
Ci Co-60 source. It is desired to calibrate the 100 to 1000 mR/hr range
of the instrument at +/- 20% at two locations on the range. The two
locations are at the lower limit plus 15% and the upper limit minus 15%
of the range at that point. If the instrument response was +30% of the
required lower level reading, it would read approximately:
a. 325 mR/hr
b. 150 mR/hr
c. 111 mR/hr
d. 195 mR/hr
2.96 inches Ans✓✓✓ A material with a 9.83 inch Tenth-Value Layer,
has a Half-Value Layer of:
a. 0.983 inches
b. 2.96 inches
c. 3.24 inches
d. 4.92 inches
20.6 ft Ans✓✓✓ A survey instrument is to be calibrated using a 3.4 Ci
Co-60 source. It is desired to calibrate the 100 to 1000 mR/hr range of
the instrument at +/- 20% at two locations on the range. The two
locations are at the lower limit plus 15% and the upper limit minus 15%
of the range at that point. What is the distance from the calibration
source to the instrument detector to obtain the calculated intensity
required at the lower limit check in the above situation?
a. 61.9 ft
b. 20.6 ft
, c. 13.2 ft
d. 39.6 ft
20% Ans✓✓✓ When radiographing a steel specimen 0.75 inches thick
with 275 kV peak X-rays, the use of a copper filter that is ___ of the
specimen thickness is recommended (if more latitude is necessary)
a. 20%
b. 10%
c. 4%
d. 15%
34 eV Ans✓✓✓ The minimum amount of energy required to produce
an ion pair in air is approximately:
a. 100 eV
b. 68 keV
c. 0.510 MeV
d. 34 eV
6.25% Ans✓✓✓ After 4 half lives, what percentage of a radioisotope's
life remains?
a. 25%
b. 12.5%
c. 6.25%
d. 3.12%
