Basic Radiobiology for the Radiotherapy Physicist: Colin Orton, Question Set

Basic Radiobiology for the Radiotherapy Physicist: Colin Orton, Question set

1. The principle radiobiological rationale for fractionating radiotherapy treatments is that

A. this improves utilization of treatment machines

B. cells of late-reacting normal tissues are better able to repair than those of most cancers

C. this gives the staff time to rest between treatments

D. survival curves for cancer cells are typically “curvier” than for normal cells

E. cancer cells repair faster than normal cells so session times have to be kept short

Correct answer: B

Ref: Colin G. Orton, “Fractionation: Radiobiological Principles and Clinical Practice”, in Treatment Planning in Radiation Oncology, Eds. Khan and Gerbi, 3rd Edition, Chapter 21, Lippincott Williams & Wilkins, New York, New York, 2011

2. The main reason why we need to leave at least six hours between fractions is to

A. allow time for late-reacting normal tissue cells to repopulate

B. allow time for tumor cells to repopulate

C. give the patient ample time to rest between treatments

D. allow time for late-reacting normal tissue cells to repair

E. allow time for cancer cells to repair

Correct answer: D

Ref: Basic Clinical Radiobiology, Eds. Joiner and van der Kogel, 4th Edition, p. 145, Hodder Arnold, London, England, 2009

3. One reason why the CHART technique might be better for reducing the overall time of a course of treatment than conventional accelerated fractionation is that, with CHART

A. there will be increased probability of reoxygenation of hypoxic cancer cells

B. treatments are more convenient to deliver

C. there is reduced risk of late complications

D. there is a reduced risk of severe acute complications

E. severe acute reactions peak after the course of radiotherapy has been completed

Correct answer: E

Ref: Ref: Colin G. Orton, “Fractionation: Radiobiological Principles and Clinical Practice”, in Treatment Planning in Radiation Oncology, Eds. Khan and Gerbi, 3rd Edition, Chapter 21, Lippincott Williams & Wilkins, New York, New York, 2011

4. Hypofractionation might better than other forms of fractionation because

A. with fewer fractions,reduced reoxygenation will protect late-reacting normal tissues

B. longer treatment times will allow some cancer cells to repair

C. fewer fractions will be more cost-effective

D. shorter courses of radiotherapy will reduce the risk of acute reactions

E. shorter courses of radiotherapy will reduce the risk of late complications

Correct answer: C