Systematisation of spatial uncertainties for comparison between a MR and a CT-based radiotherapy workflow for prostate treatments

Table 1 Estimated positioning uncertainties CT resp. MR based treatment procedure

	CT based workflow						MR based workflow
	CT/MR-systematic			CT/MR-Random			MR-systematic			MR-random
Contributing factor	ΣRL mm	ΣAP mm	ΣHF mm	σRL Mm	σAP mm	σgHF mm	ΣRL mm	ΣAP mm	ΣHF mm	σRL mm	σAP mm	σHF mm
Prostate delineation	1.8	1.8	2.8	-----	-----	-----	1.8	1.8	2.8	-----	-----	-----
Geometrical distortions	0.2	0.2	0.2	-----	-----	-----	0.2	0.2	0.2	-----	-----	-----
MR to CT registration	2	2	2	-----	-----	-----	-----	-----	-----	-----	-----	-----
*Total treatment planning uncertainty*	*2.7*	*2.7*	*3.4*	-----	-----	-----	*1.8*	*1.8*	*2.8*	-----	-----	-----
Intra-fraction motion	-----	-----	-----	0.4	1.4	1.4	-----	-----	-----	0.4	1.4	1.4
CT to X-ray registration	-----	-----	-----	0.7	0.7	1.4	-----	-----	-----	-----	-----	-----
Fidutial marker uncertainty	1.0	1.0	1.0	-----	-----	-----	-----	-----	-----	-----	-----	-----
X-ray Imaging uncertainty	1.0	1.0	1.0	-----	-----	-----	-----	-----	-----	-----	-----	-----
MR Imaging uncertainty/distortion	-----	-----	-----	-----	-----	-----	0.5	0.5	0.5	0.5	0.5	0.5
MR to MR registration	-----	-----	-----	-----	-----	-----	-----	-----	-----	0.5	0.5	1.25
Calibration vector determination	-----	-----	-----	-----	-----	-----	0.1	0.2	0.1	-----	-----	-----
Weight correction	-----	-----	-----	-----	-----	-----	-----	0.6	0.2	-----	-----	-----
Docking mechanism	-----	-----	-----	-----	-----	-----	-----	-----	0.5	-----	-----	0.7
*Total Set-up uncertainty*	*1.4*	*1.4*	*1.4*	*0.8*	*1.6*	*2.0*	*0.5*	*0.8*	*0.7*	*0.8*	*1.6*	*2.1*
Total uncertainty	3.0	3.0	3.7	0.8	1.6	2.0	1.9	2.0	2.9	0.8	1.6	2.1

ISSN: 1748-717X