Radiobiologically equivalent regimes

Question 1

What is the α/β for Generic Early Reacting tissue?

Answer 1

10

Question 2

What is the α/β for Generic Late Reacting tissue?

Answer 2

3

Question 3

What is the α/β for Early Reacting Head & Neck tissue?

Answer 3

10

Question 4

What is the α/β for Late Reacting Head & Neck tissue?

Answer 4

3 (non-CNS)

Question 5

What is the α/β for Early Reacting CNS tissue?

Answer 5

10

Question 6

What is the α/β for Late Reacting CNS tissue?

Answer 6

2

Question 7

What is the α/β for Early Reacting NSCLC tissue?

Answer 7

10

Question 8

What is the α/β for Late Reacting NSCLC tissue?

Answer 8

4.5

Question 9

What is the α/β for Early Reacting Cervix tissue?

Answer 9

14

Question 10

What is the α/β for Late Reacting Cervix tissue?

Answer 10

3

Question 11

What is the α/β for Early Reacting Breast tissue?

Answer 11

10

Question 12

What is the α/β for Late Reacting Breast tissue?

Answer 12

3

Question 13

What is the α/β for Early Reacting Prostate tissue?

Answer 13

1.5-5

Question 14

What is the α/β for Late Reacting Prostate tissue?

Answer 14

3

Question 15

What does the radiobiological value ‘k’ represent?

Answer 15

‘dose’ loss per day once treatment exceeds TDelay (time from commencing treatment until onset of rapid re-population)
It is sometimes given the units of ERD/day.

Question 16

What is the Generic radiobiological k value?

Answer 16

0.42

Question 17

What is the H&N radiobiological k value?

Answer 17

0. 1 if T<28

0. 9 if T>28

Question 18

What is the CNS radiobiological k value?

Answer 18

0. 1 if T<28

0. 9 if T>28

Question 19

What is the NSCLC radiobiological k value?

Answer 19

0. 1 at start

0. 9 at end

Question 20

What is the Cervix radiobiological k value?

Answer 20

0.5

Question 21

What is the Breast radiobiological k value?

Answer 21

0.3

Question 22

What is the Prostate radiobiological k value?

Answer 22

0.2

Question 23

What is the Generic Tdelay value?

Answer 23

28

Question 24

What is the H&N Tdelay value?

Answer 24

0 if T<28

28 if T>28

Question 25

What is the CNS Tdelay value?

Answer 25

0 if T<28

28 if T>28

Question 26

What is the Breast Tdelay value?

Answer 26

35

Question 27

Which radiobiological terms can be used for comparing different fractionation regimes?

Answer 27

EQDX, EQD2, BED

Question 28

What are the consequences of improved outcomes leading to increased survival?

Answer 28

Increased probability that patients will:

• experience relapse (original tumour)
• develop a new primary tumour
• require future palliative care

Question 29

What is the limiting factor of any future treatments for patients that have had radiotherapy?

Answer 29

The total OAR doses (though repair is taken into account usually with BED)

Question 30

What literature is used for guidance on management of gaps? What guidance is included?

Answer 30

Management of Gaps, 2008, RCR.
Guidance on techniques:
 - Accelerated treatments
 - multiple fractions per day
 - weekend catch up

Question 31

When would additional dose or a modified regime be required?

Answer 31

If there was a gap in treatment that took T to over the limit of Tdelay.

Question 32

What is the minimum time recommended between fractions, and why? Where does this come from?

Answer 32

> 6 hours. This allows normal tissue repair.

The value comes from RCR Guidelines 2008.