Variseed 8

The prescribed dose of ¹²⁵I seed implantation alone was 160 Gy [18 (link),19 (link)], whereas that in combination with EBRT was 110 Gy [18 (link),19 (link)]. The clinical target volume for the LDR brachytherapy included the whole prostate. The implantation was based on peripheral loading technique with real time dynamic dose calculation using VariSeed^® 8.0 (Varian Medical Systems, Palo Alto CA, USA). The target for the EBRT was determined 1 month after seed implantation, and the patients received 45 Gy (25 fractions, 1.8 Gy per fraction) using 10-MV photon energy and the three-dimensional conformal technique. The clinical target volume included both the entire prostate and the proximal third of the seminal vesicles. Post-implant dosimetry analysis was performed at 1-month post-seed implant.

Transrectal ultrasound (TRUS) images of the prostate were obtained at 0.5 cm intervals using the brachytherapy stepper (Amertek Medical Inc, Singer Island, FL, USA). Intra-operative physics planning was done with a 0.5 cm radial margin at the apex and base, ensuring that the urethra did not overlap with the 150% isodose line, and V_100% of the rectum was less than 1 cm³ (VariSeed 8.0, Varian Medical Systems, Palo Alto, CA) [9 (link)]. Rapid strands were placed peripherally and loose seeds were placed centrally; needles were placed beginning with the position furthest from the ultrasound probe to minimize image distortion.