Initial analysis of Pro-Qura: A multi-institutional database of prostate brachytherapy dosimetry

Merrick, Gregory S.; Grimm, Peter D.; Sylvester, John; Blasko, John C.; Butler, Wayne M.; Allen, Zachariah A.; Chaudhry, Usman-Ul-Haq; Mazza, Anthony; Sitter, Mike

doi:10.1016/j.brachy.2006.10.002

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Volume 6, Issue 1 , Pages 9-15, January 2007

Initial analysis of Pro-Qura: A multi-institutional database of prostate brachytherapy dosimetry

Gregory S. Merrick
- Schiffler Cancer Center, Wheeling Hospital, Wheeling, WV
- Wheeling Jesuit University, Wheeling, WV
- Corresponding author. Schiffler Cancer Center, Wheeling Hospital, 1 Medical Park, Wheeling, WV 26003-6300, USA. Tel.: +1-304-243-3490; fax: +1-304-243-5047.
Peter D. Grimm
- Seattle Prostate Institute, Seattle, WA
- ProQura, Seattle, WA
John Sylvester
- Seattle Prostate Institute, Seattle, WA
- ProQura, Seattle, WA
John C. Blasko
- Seattle Prostate Institute, Seattle, WA
- ProQura, Seattle, WA
Wayne M. Butler
- Schiffler Cancer Center, Wheeling Hospital, Wheeling, WV
- Wheeling Jesuit University, Wheeling, WV
Zachariah A. Allen
- Schiffler Cancer Center, Wheeling Hospital, Wheeling, WV
- Wheeling Jesuit University, Wheeling, WV
Usman-Ul-Haq Chaudhry
- Schiffler Cancer Center, Wheeling Hospital, Wheeling, WV
Anthony Mazza
- Schiffler Cancer Center, Wheeling Hospital, Wheeling, WV
- Wheeling Jesuit University, Wheeling, WV
Mike Sitter
- Seattle Prostate Institute, Seattle, WA
- ProQura, Seattle, WA

Received 21 July 2006; received in revised form 24 October 2006; accepted 29 October 2006.

Abstract

Purpose

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 32.9cm³ in the I-125 and Pd-103 cohorts, respectively. The mean I-125 seed activity was 0.32 and 0.26mCi for monotherapy and boost, whereas for Pd-103 the mean seed activity was 1.59 and 1.27mCi, 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 D₉₀ >90% and a V₁₀₀ >80% for both isotopes. An adequate V₁₅₀ was defined as <60% for I-125 and <75% for Pd-103.

Results

The mean V₁₀₀ and D₉₀ were 88.9% and 101.9% of prescription dose, respectively. When analyzed in terms of patient sequence number for each institution, the mean V₁₀₀ for the first 10 patients was 87.4% and increased to 88.6% for patients 11–20 (p=0.036). Similarly, the mean D₉₀ for the first 10 patients was 98.9%, whereas for the second cohort of 10 patients the mean D₉₀ increased to 102.2% (p=0.001). In terms of mean V₁₀₀ and D₉₀, 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” (V₁₀₀ <80% and/or D₉₀ <90%). Approximately 16% of all implants were deemed “too hot” (D₉₀ >140% or V₁₅₀ >60% for I-125 or >75% for Pd-103).

Conclusions

Although a learning curve exists for prostate brachytherapy, high-quality brachytherapy is achievable in approximately 75–80% of patients treated at community centers.

Keywords: Prostate brachytherapy, Quality, Dosimetry, Pd-103, I-125