Advanced TP

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

 Possible to move from isocentre dose (CRT) to median dose (IMRT) with confidence

• NB useful to add units e.g D 50 %

or V 20 Gy