MDCB Practice Questions With 100% Verified
Correct Answers
A patient is to receive 55 Gy to a tumor in the mediastinum. In order to meet the acceptable dose
limits for the spinal cord, you could:
a. use high energy photon beams to decrease the entrance dose.
b. block the spinal cord out of all treatment fields after 40 Gy is delivered.
c. use a BID treatment technique to achieve greater repair time for the normal tissue cells.
d. utilize a 3DCRT beam arrangement including oblique beam angles. - Correct Answer d. utilize a
3DCRT beam arrangement including oblique beam angles.
Which of the following statements are true for Iodine-125?
a. half-life 86.4 days.
b. has life-long radiation protection issues.
c. energy of 0.412 MeV.
d. decays exclusively by electron capture. - Correct Answer d. decays exclusively by electron capture.
The most significant effect(s) of an air cavity in a megavoltage beam treatment is:
a. a change in the spectral energy distribution within the cavity.
b. an increased primary photon transmission through the cavity.
c. an enhanced absorption of dose in and beyond the cavity.
d. a partial gain of electronic equilibrium at the cavity interface. - Correct Answer b. an increased
primary photon transmission through the cavity.
For patients with limited life expectancy the common dose fractionation for cord compression is:
a. 800cGy in 1 fraction.
b. 2000cGy in 5 fractions.
c. 3000cGy in 10 fractions.
d. 3750cGy in 15 fractions. - Correct Answer a. 800cGy in 1 fraction.
Mayneord F factor corrects PDD for:
a. heterogeneity.
b. scatter.
, c. Inverse square.
d. exponential attenuation. - Correct Answer b. Inverse square- does not correct for scatter
For quality assurance of brachytherapy treatment planning computers, the dose rates should agree
with published data tables to which of the following degrees?
a. +- 1%
b. +- 2%
c. +- 3%
d. +- 5% - Correct Answer b. +- 2%
The expected accuracy of treatment planning systems that perform brachytherapy dose calculations
should be within: a. +/- 3%
b. +/- 5%
c. +/- 7%
d. +/- 10% - Correct Answer b. +/- 5%
With LINAC based SBRT/SABR and a plan that has a 100% maximum IDL, what is the typical range of
prescription isodose line covering the PTV?
a. 40 - 60 %
b. 60 - 90 %
c. 90 - 100 %
d. > 100 % - Correct Answer c. 90 - 100 %
The ratio of the dose rate of a given field size to the dose rate of the reference field size is:
a. Relative output factor
b. Back scatter factor
c. Percent depth dose
d. Tissue maximum ratio - Correct Answer A. Relative output factor
During which stage of mitosis do the chromosomes align across the equator of the spindle fibers?
a. prophase
b. metaphase
Correct Answers
A patient is to receive 55 Gy to a tumor in the mediastinum. In order to meet the acceptable dose
limits for the spinal cord, you could:
a. use high energy photon beams to decrease the entrance dose.
b. block the spinal cord out of all treatment fields after 40 Gy is delivered.
c. use a BID treatment technique to achieve greater repair time for the normal tissue cells.
d. utilize a 3DCRT beam arrangement including oblique beam angles. - Correct Answer d. utilize a
3DCRT beam arrangement including oblique beam angles.
Which of the following statements are true for Iodine-125?
a. half-life 86.4 days.
b. has life-long radiation protection issues.
c. energy of 0.412 MeV.
d. decays exclusively by electron capture. - Correct Answer d. decays exclusively by electron capture.
The most significant effect(s) of an air cavity in a megavoltage beam treatment is:
a. a change in the spectral energy distribution within the cavity.
b. an increased primary photon transmission through the cavity.
c. an enhanced absorption of dose in and beyond the cavity.
d. a partial gain of electronic equilibrium at the cavity interface. - Correct Answer b. an increased
primary photon transmission through the cavity.
For patients with limited life expectancy the common dose fractionation for cord compression is:
a. 800cGy in 1 fraction.
b. 2000cGy in 5 fractions.
c. 3000cGy in 10 fractions.
d. 3750cGy in 15 fractions. - Correct Answer a. 800cGy in 1 fraction.
Mayneord F factor corrects PDD for:
a. heterogeneity.
b. scatter.
, c. Inverse square.
d. exponential attenuation. - Correct Answer b. Inverse square- does not correct for scatter
For quality assurance of brachytherapy treatment planning computers, the dose rates should agree
with published data tables to which of the following degrees?
a. +- 1%
b. +- 2%
c. +- 3%
d. +- 5% - Correct Answer b. +- 2%
The expected accuracy of treatment planning systems that perform brachytherapy dose calculations
should be within: a. +/- 3%
b. +/- 5%
c. +/- 7%
d. +/- 10% - Correct Answer b. +/- 5%
With LINAC based SBRT/SABR and a plan that has a 100% maximum IDL, what is the typical range of
prescription isodose line covering the PTV?
a. 40 - 60 %
b. 60 - 90 %
c. 90 - 100 %
d. > 100 % - Correct Answer c. 90 - 100 %
The ratio of the dose rate of a given field size to the dose rate of the reference field size is:
a. Relative output factor
b. Back scatter factor
c. Percent depth dose
d. Tissue maximum ratio - Correct Answer A. Relative output factor
During which stage of mitosis do the chromosomes align across the equator of the spindle fibers?
a. prophase
b. metaphase
