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In favour of using

compiled by Andreo

Current clinical experience is mostly based on dose-to-water, hence the use

of

allows direct

compliance with previous clinical experience

and with treatment planning based on analytical algorithms.

o

Doses reported in clinical trials, and therapeutic and normal-tissue

tolerance criteria, are based on

.

Reference dosimetry (beam calibration) of accelerators relies on dosimetry

protocols yielding a

reference absorbed dose to water

,

,

, which is

used to normalize the output of the TPS.

o

This is the reference quantity at the clinic, irrespective of the type of

calibration coefficient of the ionization chamber used, either in terms of

absorbed dose-to-water or air-kerma.

MCTP relies on the assumption that the codes used are ‘

accurate

’,

irrespective of the sometimes crude approximations made in the physical

models of these systems, often simpler than those in general MC codes.

April 2017

42

From P. Andreo, "Dose to 'water-like' media or dose to tissue in MV photons

radiotherapy treatment planning: still a matter of debate," Phys. Med. Biol. 60,

309-337 (2015)