MDCB 2023 Test 2 questions with verified answers
A 12 MeV electron beam displays which of the following
characteristics?
A. Depth of the therapeutic range is ~ 3.0 cm.
B. Depth of 80% isodose is ~ 4.0 cm
C. Depth of the practical range is < 5 cm
D. Depth of maximum dose is on the skin. Ans✓✓✓ B. Depth of 80%
isodose is ~ 4.0 cm
A film of an implant is taken with the source at 100 cm and the film at
120 cm. The length of a 2 cm long source on the film is:
A. 1.6 cm.
B. 1.8 cm.
C. 2.2 cm.
D. 2.4 cm. Ans✓✓✓ D. 2.4 cm.
A patient is treated for lung cancer using AP/PA parallel-opposed,
equally weighted fields at 180 cGy/day. An anterior 30- degree wedge is
used daily, with a factor of 0.617. This factor was accidentally left out of
the calculation for the first 4 days of treatment, but the wedge was
used for treatment. What total dose did the patient receive after 4 days
of treatment?
A. 484 cGy
B. 544 cGy
, C. 582 cGy
D. 944 cGy Ans✓✓✓ C. 582 cGy
A patient is treated with a 6 MV photon beam, 12.5 x 12.5 cm2 at 110
cm SAD to a 9.0 cm depth. The machine is calibrated to deliver 1.0 cGy
per monitor unit at dmax for a 10 x 10 cm2 field at 100SSD. The number
of monitor units required to deliver 150 cGy at the isocenter is:
TISSUE MAXIMUM RATIO (TMR) FOR 6 MV PHOTONS
Depth (cm)
1.5 10 x 10 cm2 12 x 12 cm2 14 x 14 cm2
9.0 1.000 1.000 1.000
0.810 0.818 0.824
A. 183.
B. 210.
C. 247.
D. 221 Ans✓✓✓ D. 221
A radioactive material is assayed at noon and measures 10.0 mCi. The
following day at noon, the radioactive material is assayed and measures
8.0 mCi. What is the half-life of the material?
A. 60.0 hours
B. 65.4 hours
C. 74.5 hours
A 12 MeV electron beam displays which of the following
characteristics?
A. Depth of the therapeutic range is ~ 3.0 cm.
B. Depth of 80% isodose is ~ 4.0 cm
C. Depth of the practical range is < 5 cm
D. Depth of maximum dose is on the skin. Ans✓✓✓ B. Depth of 80%
isodose is ~ 4.0 cm
A film of an implant is taken with the source at 100 cm and the film at
120 cm. The length of a 2 cm long source on the film is:
A. 1.6 cm.
B. 1.8 cm.
C. 2.2 cm.
D. 2.4 cm. Ans✓✓✓ D. 2.4 cm.
A patient is treated for lung cancer using AP/PA parallel-opposed,
equally weighted fields at 180 cGy/day. An anterior 30- degree wedge is
used daily, with a factor of 0.617. This factor was accidentally left out of
the calculation for the first 4 days of treatment, but the wedge was
used for treatment. What total dose did the patient receive after 4 days
of treatment?
A. 484 cGy
B. 544 cGy
, C. 582 cGy
D. 944 cGy Ans✓✓✓ C. 582 cGy
A patient is treated with a 6 MV photon beam, 12.5 x 12.5 cm2 at 110
cm SAD to a 9.0 cm depth. The machine is calibrated to deliver 1.0 cGy
per monitor unit at dmax for a 10 x 10 cm2 field at 100SSD. The number
of monitor units required to deliver 150 cGy at the isocenter is:
TISSUE MAXIMUM RATIO (TMR) FOR 6 MV PHOTONS
Depth (cm)
1.5 10 x 10 cm2 12 x 12 cm2 14 x 14 cm2
9.0 1.000 1.000 1.000
0.810 0.818 0.824
A. 183.
B. 210.
C. 247.
D. 221 Ans✓✓✓ D. 221
A radioactive material is assayed at noon and measures 10.0 mCi. The
following day at noon, the radioactive material is assayed and measures
8.0 mCi. What is the half-life of the material?
A. 60.0 hours
B. 65.4 hours
C. 74.5 hours
