D:-60 cm
Correct Answer:- Option-B
Question29:-Which is false with regard to 6MV photon beam ?
A:-Depth of maximum dose = 1.5 cm
B:-10 cm PDD = 61%
C:-Small penumbra
D:-Horns (beam intensity off-axis) due to flattening filter design is approximately 9%
Correct Answer:- Option-B
Question30:-With regard to composition of Lipowitz metal which is wrong
A:-13.3% tin
B:-50% bismuth
C:-3+6.7% lead
D:-10% cadmium
Correct Answer:- Option-C
Question31:-With regard to radiation treatment of patients with cardiac pacemakers which is wrong
A:-Pacemaker-implanted patients should never be treated with a betatron.
B:-Always keep the pacemaker outside the machine-collimated radiation beam, both during treatment and when taking
Portal films

C:-Before treatment, estimate and record the dose (from scatter) to be received by the pacemaker. The total
accumulated dose should not exceed approximately 1 Gy

D:-If treatment with these guidelines is not possible the physician should consider having the pacemaker either
temporarily of permanently moved before irradiation

Correct Answer:- Option-C
Question32:-With respect to interaction of electron beam with bone which is false ?

A:-The isodose contours in the shadow of the bone are shifted proximally

B:-Dose outside (inside) the bone-water interface increases (decreases) by approximately 15% as a result of loss of
side scatter equilibrium

C:-The lateral dimension of the region having its dose perturbed by the bone increases with depth

D:-Maximum dose increase expected as a result of back scattered electrons is 5% and the maximum dose increase
expected inside bone and in adjacent exit tissue is approximately 7%

Correct Answer:- Option-B
Question33:-Wrong about hot spot as per ICRU Report 62

A:-Volume outside PTV

B:-It receives dose >100% of specified PTV dose

C:-15mm diameter

D:-At least 2 “cm*(2)° in a section

Correct Answer:- Option-D

Question34:-The difference between the volume enclosed by the external contour of the patient and that of the CTVs and
OARs on the slice that have been imaged is

A:-Treated volume
B:-PRV
C:-Modified PTV
D:-None of the above
Correct Answer:- Option-D
Question35:-Which of the following is not correct for Rando phantoms ?

A:-They are used for determining the radiation absorption and reflection characteristics of the human body or a specific
organ
B:-The phantom is made of human tissue-equivalent materials to work with only for x-rays
C:-The bones in the phantom are real human bones and the same cavities are present as in the human body
D:-Phantom slice are 2.5 cm thick each. There are 3x 3 ‘cm*2° dosimetric spaces in each slice for TLD
Correct Answer:- Option-B
Question36:-What is the flexure dose ?
A:-Alpha/beta x 0.1
-Alpha/beta x 0.2
C:-Alpha/beta x 0.37
D:-Alpha/beta x 0.63
Correct Answer:- Option-A
Question37:-Which of the following match-ups is not correct concerning tissue and organ response to radiation ?
A:-Michalowski-flexible vs. hierarchical and alpha by beta ratio
B:-Rubin and Casarett-proliferation kinetics