No attempt was made to treat the pelvic lymph nodes. The most common dose prescription was 46 Gy
in 23 fractions (46 Gy/23), delivering 10 fractions daily for a fortnight, prescribed at the International Commission on Radiation Units check details and Measurements prescription point, using 18 MV photons. Patients were given instructions to have an empty rectum and “comfortably” full bladder for the treatment. Gold fiducial markers were used with a daily image-guided setup protocol since 2007. In all patients, the HDRB was used as a “boost” in combination with EBRT. Since initiation of the HDRB program, three progressive, escalated fractionation schedules were used. From November 1998 to August 2000 a schedule of 20 Gy/4 was used. From September 2000 to June 2006, the schedule changed to 18 Gy/3. From July 2006 until November 2008,
19 Gy/2 was the standard. Two patients planned to receive 18 Gy/3, but received one fraction ZVADFMK of 6 Gy and a second fraction of 10 Gy (16 Gy/2). This was because of the delays on Day 2, preventing a third fraction being delivered in a timely fashion. The technique has been previously described (8). Up until July 2006, metal needles were used. Subsequently, plastic catheters were used in an attempt to reduce trauma. These needles or catheters were placed transperineally using transrectal ultrasound and fluoroscopic imaging for guidance. The needles or catheters were placed within the bladder lumen to ensure adequate coverage of the prostate base. Before September 2005, replanning was not routine. Since then, patients were re-CT imaged on the simulator CT but only replanned if the needle movement
was estimated to be greater than 1 cm in the caudal DCLK1 direction. Since August 2008, all patients were replanned for each fraction. The identification of the apex in the planning images is essential to ensure adequate coverage of the prostate. Before September 2005, this was identified based on the planning CT images. Since September 2005, a fiducial marker has been placed at the apex under ultrasound guidance and used as a reference to improve the identification of the apex on the planning CT images. The target volume for the HDR component was the prostate with up to 6 mm in the cranial–caudal direction to account for microscopic extension and potential needle movement. Patients were planned using Plato (Nucletron, Veenendaal, The Netherlands) planning software until October 2009, since when the Nucletron Oncentra (Nucletron) planning system was routinely used. All fractions were given over one admission, at least 6 h apart. The HDRB was delivered by 192Ir source automatically afterloaded with a microSelectron 192Ir (Nucletron). As the prescribed dose changed over time, the dose to the urethra was limited so that no more than 10% of the urethral volume was to receive greater than 120% of the prescribed dose (D10 ≤ 120%).