Radiobiology 3

Question 1

What do quantec and emami figures refer to?

Answer 1

1.8-2.0 Gy daily fractionation.
Total dose is also considered.
Changing the way dose is delivered can change the OAR and effects.

Question 2

What does the triangle analogy refer to?

Answer 2

Total dose and biological effect around the right angle. Angle ‘d’ is the dose per fraction.
Basically, changing the dose per fraction has a direct impact on the biological effect. (good if tumour response, not if OAR)

Question 3

What is NTCP?

Answer 3

Normal Tissue Complication Probability. It is always a secondary consideration to TCP.

Question 4

OAR - Bladder?

Answer 4

Volume consistency problems are common, consequently bladder prep is used.

Not usually a dose limiting structure.

Hard to model mathematically.

Question 5

OAR - Rectum?

Answer 5

Must be consistent in defining the sup and inf borders. Size can change.