MDCB Practice Set 3 Questions with

MDCB Practice Set 3  Questions with Complete Solutions (Latest 2025) Which of the following statements regarding the geometric penumbra is true?

• Penumbra size is not dependent on the source size.
• The penumbra decreases as block to skin distance

increases, all other factors being equal.

• The penumbra increases as the distance from the source

increases, all other factors being equal.

• In general, the penumbra will become sharper on an

accelerator as the collimator setting is increased. - Correct Answers ✅C

• A 12 MeV electron beam displays which of the following

characteristics?

• Depth of the therapeutic range is ~ 3.0 cm.
• Depth of 80% isodose is ~ 4.0 cm
• Depth of the practical range is < 5 cm
• Depth of maximum dose is on the skin. - Correct

Answers ✅B

• Which calculation method independently calculates the

primary and the scattered components of dose at a point in the calculation volume?

• Convolution superposition 1 / 2

MDCB Practice Set 3  Questions with Complete Solutions (Latest 2025)

• Ray tracing
• Manchester
• Monte Carlo - Correct Answers ✅A
• A collimated field size is 10 x 10 cm2

. Thirty percent of the field is blocked. The effective field size is approximately how many cm2 ?

A. 5.5

B. 6.5

C. 7.5

• 8.5 - Correct Answers ✅D
• Which of the following statements is correct regarding the

concept of equivalent squares in dose calculation?

• A rectangular field is equivalent to a square field if they

have the same Area/Perimeter ratio.

• A rectangular photon field has the same output and

percentage depth dose (PDD) as a square field of the same area.

• Standard equivalent square table values for rectangular

fields are applied to electron

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