Prospective multi-center dosimetry study of low-dose Iodine-125 prostate brachytherapy performed after transurethral resection

Abstract

PurposeTo evaluate in a multicenter setting the ability of centers to perform pre-implant permanent prostate brachytherapy planning, fulfilling dosimetric goals and constraints based on the Groupe de Curiethérapie-European Society for Radiotherapy and Oncology guidelines in the setting of implantation after prior prostate transurethral resection (TURP).Material and methodsA reference transrectal ultrasound image set of the prostate gland from a patient who had undergone TURP was used. Contouring of the prostate, clinical target volume and organs at risk was performed by the coordinating center. Goals and constraints regarding the dosimetry were defined.ResultsSeventeen of twenty-five centers invited to participate were able to import the Digital Imaging and Communications in Medicine-images into their planning computer and plan the implant using the defined guidelines. All centers were able to plan treatment, and achieve the recommended objectives and constraints. However, sector analysis has shown a risk of under-dosage in the anterior part of the prostate.ConclusionsCorrect pre-implantation planning with adherence to protocol guidelines and in compliance with defined dosimetric constraints seems feasible in a post-TURP setting, at least on a theoretical basis. A prospective study evaluating the outcome of prostate brachytherapy performed after TURP can therefore be undertaken with an expectation of a correct dosimetry in the multicenter setting.

Pre-plan parameters predict post-implant D 90 ≥ 140 Gy for 125 I permanent prostate implants

“…A multi-institutional study comparing 17 centers pre-plans for a single post-TURP patient, showed a propensity to lower doses anteriorly as compared to posteriorly [25]. Neither the previous studies nor our results showed statistical significance of IA quarter metrics as predictors in multivariate models.…”

The impact of body mass index on dosimetric quality in low-dose-rate prostate brachytherapy

“…Although other studies have reported that prostate volume also affects D 90 , our study did not find this correlation to be statistically significant, likely because all of our patients had a prostate volume < 50 cc. Previous studies analyzing implant quality have reported a tendency for lower doses to be delivered anteriorly as compared to the posterior prostate in patients treated with LDR brachytherapy [19, 20]. In a multi-institutional analysis of 4547 patients, Merrick et al .…”

Influence of Zonal Dosimetry on Prostate Brachytherapy Outcomes

“…As such, attention to dose painting is critical for tumor control and limiting toxicities. This is especially important for patients at higher risk of significant toxicity, such as those with a history of TURP [28].…”