A similar technique of CIRT for prostate cancer, which has been reported from NIRS, was used in the present study [7 (link)]. The feet of patients were positioned in a customized cradle (Moldcare; Alocare, Tokyo, Japan) and the pelvis was immobilized with a low-temperature thermoplastic sheet (Shellfitter; Kuraray, Co., Ltd., Osaka, Japan). At CT simulation, the bladder was filled with 100 mL sterilized saline and the rectum was emptied using an enema.
Treatment planning was performed using CT images of 2 mm thickness with fused MRI images with Xio-N (Elekta, Stockholm, Sweden and Mitsubishi Electric, Tokyo, Japan) [8 (link)]. The clinical target volume (CTV) included the prostate and the proximal seminal vesicles (SV). In T3b cases, we include the part of seminal vesicle as CTV where was involved by prostate cancer at diagnosis (pre neoadjuvant hormonal therapy) at least. The initial planning target volume (PTV1) was created by adding the anterior and lateral margins of 10 mm, cranial and caudal margins of 6 mm, and a posterior margin of 5 mm to the CTV, with lateral margins to the SV of 3 mm. According to the protocol from the NIRS, boost therapy was performed using the second PTV (PTV2), in which the posterior edge was set in front of the anterior wall of the rectum after the completion of nine fractions while the other margins remained the same as for PTV1 [9 (link)]. Each field was defined using spread-out Bragg peak and shaped by multi-leaf collimators and compensation bolus for each patient.
CIRT was performed at a total dose of 57.6 Gy (RBE) in 16 fractions over 4 weeks, with a fractional dose of 3.6 Gy (RBE) at four fractions a week. One field was used for each session, including one anterior field and a pair of lateral ports for PTV1 and another pair of lateral ports for PTV2. The bladder was also filled with 100 mL sterilized saline at each treatment session from the anterior direction. Patient positioning was three-dimensionally corrected using the same treatment couch used at the NIRS. All treatment plans were approved by the institutional conference prior to administering treatment.
Treatment planning was performed using CT images of 2 mm thickness with fused MRI images with Xio-N (Elekta, Stockholm, Sweden and Mitsubishi Electric, Tokyo, Japan) [8 (link)]. The clinical target volume (CTV) included the prostate and the proximal seminal vesicles (SV). In T3b cases, we include the part of seminal vesicle as CTV where was involved by prostate cancer at diagnosis (pre neoadjuvant hormonal therapy) at least. The initial planning target volume (PTV1) was created by adding the anterior and lateral margins of 10 mm, cranial and caudal margins of 6 mm, and a posterior margin of 5 mm to the CTV, with lateral margins to the SV of 3 mm. According to the protocol from the NIRS, boost therapy was performed using the second PTV (PTV2), in which the posterior edge was set in front of the anterior wall of the rectum after the completion of nine fractions while the other margins remained the same as for PTV1 [9 (link)]. Each field was defined using spread-out Bragg peak and shaped by multi-leaf collimators and compensation bolus for each patient.
CIRT was performed at a total dose of 57.6 Gy (RBE) in 16 fractions over 4 weeks, with a fractional dose of 3.6 Gy (RBE) at four fractions a week. One field was used for each session, including one anterior field and a pair of lateral ports for PTV1 and another pair of lateral ports for PTV2. The bladder was also filled with 100 mL sterilized saline at each treatment session from the anterior direction. Patient positioning was three-dimensionally corrected using the same treatment couch used at the NIRS. All treatment plans were approved by the institutional conference prior to administering treatment.
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