General CNS Constraints

Question 1

Spinal Cord

Answer 1

max 50Gy (full cord cross-section); tolerances increases by 25% 6 months after 1st course (QUANTEC)

Question 2

Brain max

Answer 2

72Gy (partial brain); avoid>2Gy/fx or hyperfractionation (QUANTEC)

Question 3

Chiasm / optic nerves

Answer 3

max55Gy (QUANTEC)

Question 4

Brainstem

Answer 4

Entire brainstem <1-10cc (QUANTEC)

Question 5

Eyes (globe)

Answer 5

Mean <35Gy (RTOG 0225), max 54Gy (RTOG 0615)

Question 6

Lens

Answer 6

max 7Gy (RTOG 0539)

Question 7

Retina

Answer 7

max 50Gy (RTOG 0539)

Question 8

Lacrimal Gland

Answer 8

max 40Gy (Parsons)

Question 9

Inner ear / cochlea

Answer 9

mean <35Gy with concurrent cisplatin

Question 10

Pituitary gland

Answer 10

max 45Gy (for panhypopituitarism, lower for GH deficiency)

Question 11

Cauda equina

Answer 11

max 60Gy (Emami)

Question 12

Spinal cord (single fraction)

Answer 12

max 13Gy (if 3fx, max 20Gy) (QUANTEC)

Question 13

Brain (single fraction)

Answer 13

V12Gy<5-10cc (QUANTEC)

Question 14

Chiasm / optic nerves (single fraction)

Answer 14

max 10Gy (QUANTEC)

Question 15

Brainstem (single fraction)

Answer 15

max 12.5Gy (QUANTEC)

Question 16

Sacral Plexus (single fraction)

Answer 16

V18Gy <5cc (RTOG 0631)

Question 17

Cauda equina (single fraction)

Answer 17

V16Gy <5cc (RTOG 0631)