IMRT 2018

3"parameters"affecting dose distribution"and"treatment time

• Fan%beam%thickness%(FBT) • Modulation%Factor%(MF) • Pitch%(P)

Parameter:

Effect%on: Dose%distrib. Treatment%time%

FBT:%%% ! MF:%%% ! Pitch: !

worsens improves worsens

decreases (directly%proportional)

increases decreases

A%judicious/wise%selection%of%pitch,%modulation%factor%and%field%size%is%required%to produce%a%homogeneous%dose%distribution%along%with%an%acceptable%treatment%time.

Hui: MP 32 (10) 2005, 3214-3224