A retrospective comparison of two different immobilization systems for radiotherapy of extremity soft tissue sarcomas and its influence on CTV-PTV margin

Journal of the Egyptian National Cancer Institute

Table 3 Random/ Systematic error and PTV margins for each immobilization technique

Variable	Random error				Systemic error				PTV Margin (Van Herk’s)
Variable	Vertical	Longitudinal	Lateral	Angle	Vertical	Longitudinal	Lateral	Angle	Vertical	Longitudinal	Lateral
Vac-Loc™	0.59	0.65	1.23	3.17	0.16	0.07	0.17	0.76	0.82	0.62	1.29
Thermoplastic Cast	0.81	0.56	0.56	2.26	0.06	0.04	0.11	0.54	0.71	0.49	0.67

Random errors, systemic errors and PTV margins measured in cm. Angular rotation random and systemic errors measured in Degree