Initial analysis of Pro-Qura: A multi-institutional database of prostate brachytherapy dosimetry (original) (raw)

The study aimed to analyze the Pro-Qura database in terms of patient implant sequence number for each institution to determine evidence for a dosimetric learning curve. METHODS AND MATERIALS: In the Pro-Qura database, 2833 of a total of 4614 postplans from 57 brachytherapists were analyzed for evidence of a dosimetric learning curve. The median time between implant and postimplant CT scan was 30 days. I-125 was used in 2123 patients (1687 monotherapy and 536 boost) and Pd-103 in 710 patients (367 monotherapy and 343 boost). Preimplant prostate volume was 35.3 and 32.9 cm 3 in the I-125 and Pd-103 cohorts, respectively. The mean I-125 seed activity was 0.32 and 0.26 mCi for monotherapy and boost, whereas for Pd-103 the mean seed activity was 1.59 and 1.27 mCi, respectively. Postimplant dosimetry was performed in a standardized fashion by overlaying the preimplant ultrasound and the postimplant CT scan. Criteria for implant adequacy included a D 90 O90% and a V 100 O80% for both isotopes. An adequate V 150 was defined as !60% for I-125 and !75% for Pd-103. RESULTS: The mean V 100 and D 90 were 88.9% and 101.9% of prescription dose, respectively. When analyzed in terms of patient sequence number for each institution, the mean V 100 for the first 10 patients was 87.4% and increased to 88.6% for patients 11e20 ( p 5 0.036). Similarly, the mean D 90 for the first 10 patients was 98.9%, whereas for the second cohort of 10 patients the mean D 90 increased to 102.2% ( p 5 0.001). In terms of mean V 100 and D 90 , there was minimal further change for subsequent 10 patient institutional groupings of patient sequence numbers. For the first 10 cases, 27.2% were deemed ''too cool'' (V 100 !80% and/or D 90 !90%). Approximately 16% of all implants were deemed ''too hot'' (D 90 O140% or V 150 O60% for I-125 or O75% for Pd-103). CONCLUSIONS: Although a learning curve exists for prostate brachytherapy, high-quality brachytherapy is achievable in approximately 75e80% of patients treated at community centers.