Dose constraints

Question 1

Brainstem constraint

Answer 1

Max dose <54 Gy

Question 2

Cochlear constraint

Answer 2

Mean dose <45 Gy

Question 3

Globe (including retina)

Answer 3

Mean dose <35 Gy
Max dose <50 Gy

Question 4

Retina

Answer 4

Max dose <50 Gy

Question 5

Hippocampus

Answer 5

ALARA
Mean <5-10 Gy

Where possible spare the hippocampus contralateral to the tumour to <5Gy if not possible to spare bilaterally

Question 6

Inner ear

Answer 6

Max <45 Gy with the aim to keep doses <40 Gy

Question 7

Lacrimal gland

Answer 7

Mean <25 Gy

Question 8

Lens

Answer 8

Max dose ideally <6 Gy

Absolute <10Gy

Question 9

Optic chiasm

Answer 9

Max dose <54 Gy

Question 10

Optic nerves

Answer 10

Max dose <54 Gy

Question 11

Pituitary gland

Answer 11

Mean <45 Gy

Question 12

Spinal cord

Answer 12

Max dose <45Gy

Question 13

What is the risk of myelopathy of spinal cord at doses 50GY, 60GY, 69Gy?

Answer 13

Max dose:
<50 Gy, to keep risk of myelopathy ≤0.2%
<60 Gy, to keep risk of myelopathy ≤6%
<69 Gy, to keep risk of myelopathy ≤50%

Question 14

What is the risk of radiation induced optic neuropathy at a dose 55-60Gy vs >60Gy?

Answer 14

max dose 55-60 Gy risk of RION <3-7%
max dose >60 Gy risk of RION 7-20%

NN had RION at 60Gy to undamaged chiasm!