MDCB: Mock Exam 2 Questions with 100

MDCB: Mock Exam 2 Questions with 100%

Verified Correct Answers A patient receiving treatment to the head and neck region has experienced a skin reaction and mucositis at a total dose much lower than anticipated. The radiation oncologist requests an evaluation of the treatment. Which of the following steps should be taken?

• recalculate the treatment plan
• ensure that the depth dose, build-up region, wedge parameters, and other pertinent information

for the treatment unit are correct

• review the treatment setup with the therapist
• recalculate the monitor unit settings
• all are correct - Correct Answer E

For megavoltage dosimetry, TLD can provide accuracy of:

• plus/minus 20%
• plus/minus 10%
• plus/minus 3%
• plus/minus 1% - Correct Answer C

With megavoltage film dosimetry, isodose curves can be measured to within:

• plus/minus 10%
• plus/minus 7% 1 / 4

• plus/minus 3%
• plus/minus 1% - Correct Answer C

In megavoltage therapy, typical use(s) of diodes is for:

• patient dosimetry
• beam scanning
• quality assurance
• all of the answers are correct - Correct Answer D

Which of the following is best suited for calibration of a megavoltage beam:

• diode detector
• thermoluminescence dosimetry
• film
• ionization chamber - Correct Answer D

The f-factor:

• is the roentgen to cGy conversion factor
• is greatest for high Z materials and low energy photons 2 / 4

• is 0.873 in air
• all of the answers are correct
• none of the answers are correct - Correct Answer D

Clinical application of MLC include which of the following?

• shaping of electron fields as a replacement for cerrobend blocks
• dynamic field shaping as a function of patient respiration
• field shaping without penumbra
• modulating beam intensity - Correct Answer D

The 104% isodose lines at the four corners of the target shown are due to the:

• inhomogeneity of the femur
• scatter from the femur
• horns of the beams
• weights of the lateral beams
• use of a wrong algorithm - Correct Answer C

Exposure is:

• the amount of energy in Joules/kg transferred from a photon beam to a material 3 / 4

• only defined for photons and charged particles below 3 MeV
• the charge liberated by photons in a given mass of air
• the absorbed dose multiplied by the quality factor
• None of the answers - Correct Answer C

The quantity that an ionization chamber actually measures is:

• roentgen
• gray
• charge
• kerma
• voltage - Correct Answer C

Geiger counters:

• are sensitive enough to detect individual photons or particles
• are less sensitive than ionization chambers
• are used to calibrate linac output
• operate on the principle of scintillation - Correct Answer A
• / 4