Patients
prostate
SEMINAL VESICLES, PROSTATE
Fifty‐nine patients were enrolled in the study in five centers: two centers in Europe, which implanted the biodegradable balloon spacer in a total of 24 patients and three centers in the USA, which implanted the SpaceOAR in 35 subjects. The study received approval by the local Ethics Committees and Institutional Review Boards. All patients underwent prostate radiotherapy with either the balloon spacer or with the SpaceOAR.Computed tomography (CT) for planning was done before and after spacer implantation for all patients. For each patient, both CT scans were used to obtain comparable “pre and post” planning simulation using identical treatment planning and dose constraints: The clinical target volume (CTV) included the prostate with seminal vesicles, the planning target volume (PTV) was defined as the CTV with margins of 5 mm in all directions (including posterior direction), the rectum was contoured as a solid structure from the anus to the rectosigmoid flexure. Contouring of the rectum was limited, to the extent possible, to the same number of corresponding CT slices on both image sets (pre and post spacer implantation).