4D Brachytherapy, a novel real-time prostate brachytherapy technique using stranded and loose seeds.

What's known on the subject? and What does the study add? There are a number of techniques used successfully to perform brachytherapy, including 2-stage procedures and realtime techniques using loose seeds. This study demonstrates a one-stage realtime brachytherapy technique using stranded seeds with improved time efficiency and clinical outcome: 4D Brachytherapy. This paper reviews the development of a new one-stage prostate brachytherapy technique (4D Brachytherapy) using a combination of stranded and loose seeds. This novel technique utilizes a nomogram constructed from over 1000 procedures to calculate the seed requirement in advance of the implant. This allows stranded seeds to be pre-ordered and loaded prior to the procedure rather than per-operatively, resulting in a more efficient use of operating room time. The use of both stranded and loose seeds may reduce the risk of migration from peripherally placed seeds via the venous plexus, whilst maintaining the flexibility to optimize the dose within the prostate and especially at the apex of the gland. Prospectively collected data show significantly improved dosimetry: median D(90) 143 and 153 Gy (P < 0.005) and median V(100) 88% and 93% (P < 0.005) for the Seattle technique and 4D Brachytherapy implant technique, respectively. Also there was a reduced short-term urinary morbidity as assessed by the change in International Prostate Symptom Score (IPSS) at 3 months and 1 year compared with the Seattle technique. Mean (sd) change in IPSS from baseline at 1 year was 2.73 (5.92) and 0.97 (5.10) for the Seattle and 4D Brachytherapy series, respectively (P < 0.049).