MDCB Practice Questions With 100 Verified

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:

• use high energy photon beams to decrease the entrance dose.
• block the spinal cord out of all treatment fields after 40 Gy is delivered.
• use a BID treatment technique to achieve greater repair time for the normal tissue cells.
• 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?

• half-life 86.4 days.
• has life-long radiation protection issues.
• energy of 0.412 MeV.
• 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 change in the spectral energy distribution within the cavity.
• an increased primary photon transmission through the cavity.
• an enhanced absorption of dose in and beyond the cavity.
• 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:

• 800cGy in 1 fraction.
• 2000cGy in 5 fractions.
• 3000cGy in 10 fractions.
• 3750cGy in 15 fractions. - Correct Answer a. 800cGy in 1 fraction.

Mayneord F factor corrects PDD for:

• heterogeneity.
• scatter. 1 / 2

• Inverse square.
• 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?

• +- 1%
• +- 2%
• +- 3%
• +- 5% - Correct Answer b. +- 2%

The expected accuracy of treatment planning systems that perform brachytherapy dose calculations

should be within: a. +/- 3%

• +/- 5%
• +/- 7%
• +/- 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?

• 40 - 60 %
• 60 - 90 %
• 90 - 100 %
• > 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:

• Relative output factor
• Back scatter factor
• Percent depth dose
• 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?

• prophase
• metaphase
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