ABR ABR Radiation Dosimetry 2

Question 1

What phantom material is required for reference dosimetry measurements per TG-51?

Accepted Answer

Liquid water

Answer

Solid water

Answer

PMMA

Answer

RW3 plastic

Question 2

Which of the following best describes the percent depth dose (PDD) curve for a megavoltage photon beam?

Accepted Answer

Builds up to a maximum then exponentially decreases

Answer

Decreases monotonically from the surface

Answer

Remains constant throughout the phantom

Answer

Peaks at the surface then rapidly drops

Question 3

What is the tissue-phantom ratio (TPR) used to characterize in radiation dosimetry?

Accepted Answer

Beam quality and off-axis output factors

Answer

Absolute dose calibration

Answer

Electron contamination

Answer

Brachytherapy source strength

Question 4

In electron beam dosimetry, what is the recommended reference depth for calibration per TG-51?

Accepted Answer

dref = 0.6·R50 – 0.1 cm

Answer

dmax

Answer

5 cm

Answer

10 cm

Question 5

What is the primary purpose of a farmer chamber's graphite wall in dosimetry?

Accepted Answer

To provide charged particle equilibrium

Answer

To reduce energy dependence

Answer

To shield against neutrons

Answer

To improve spatial resolution

Question 6

Which AAPM protocol provides dosimetry recommendations for low-energy photon brachytherapy sources such as 125I seeds?

Accepted Answer

TG-43

Answer

TG-51

Answer

TG-61

Answer

TG-142