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Prescribing
•
Specify median dose - D
median
= D
50 %
Corresponds best to previous ICRU reference point dose
(≈ isocentre dose)
•
Often close to mean dose
•
Not influenced by ‘tails’ on the DVH
•
Accurately calculated in TPSs
NB useful to add units e.g D
50 %
or V
20 Gy