SBRT 2016

Intrafractional motion

2 TYPES OF MOTION: A: Slow drift motion  Mainly posterioly and inferiorly  Can reach large extends over long time periods  Probably due to pelvic musculature relaxation or/and  Gradually Moving rectal content B: Erractic motion  Sudden and transient  Often significant extend  Probably related due to peristaltic motion C: Combination of A and B

Langen et al, IJROBP, Volume 71, Issue 4 , 15 July 2008