An example for abdomen tumors(a) CTV (in red) was 416.08 ml, PTV1(in purple; expended margins of Zhou’s recommendation) was 839.18 ml; the PTV2(in green; expended margins of this study) was 691.35 ml. (b and c) The relationship of three volume, the intersectional volume of PTV1 and PTV2 was 682.89 ml, and VPTV1−PTV2=140.16 ml (b), VPTV2−PTV1=4.45 ml (c).