Brachytherapy
Volume 7, Issue 1 , Pages 12-16, January 2008

A comparison of anatomy-based inverse planning with simulated annealing and graphical optimization for high-dose-rate prostate brachytherapy

  • Gerard C. Morton

      Affiliations

    • Department of Radiation Oncology, Odette Cancer Centre, University of Toronto, Toronto, Ontario, Canada
    • Corresponding Author InformationCorresponding author. Department of Radiation Oncology, Odette Cancer Centre, Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Avenue, Toronto, Ontario, Canada M4N 3M5. Tel.: +416-480-6165; fax: +416-480-6002.
    • ,
  • Raxa Sankreacha

      Affiliations

    • Department of Medical Physics, Odette Cancer Centre, University of Toronto, Toronto, Ontario, Canada
    • ,
  • Patrick Halina

      Affiliations

    • Department of Medical Physics, Odette Cancer Centre, University of Toronto, Toronto, Ontario, Canada
    • ,
  • Andrew Loblaw

      Affiliations

    • Department of Radiation Oncology, Odette Cancer Centre, University of Toronto, Toronto, Ontario, Canada

Received 16 July 2007; received in revised form 26 September 2007; accepted 2 October 2007. published online 26 November 2007.

Abstract 

Background and purpose

Dose distribution in a high-dose-rate (HDR) brachytherapy implant is optimized by adjusting source dwell positions and dwell times along the implanted catheters. Inverse planning with fast simulated annealing (IPSA) is a recently developed algorithm for anatomy-based inverse planning, capable of generating an optimized plan in less than 1min. The purpose of this study is to compare dose distributions achieved using IPSA to those obtained with a graphical optimization (GrO) algorithm for prostate HDR brachytherapy.

Methods and materials

This is a retrospective study of 63 consecutive prostate HDR brachytherapy implants planned and treated using on-screen GrO to a dose of 10Gy per implant. All plans were then recalculated using IPSA, without changing any parameters (contours, catheters, number, or location of dwell positions). The IPSA and GrO plans were compared with respect to target coverage, conformality, dose homogeneity, and normal tissue dose.

Results

The mean volume of target treated to 100% of prescription dose (V100) was 97.1% and 96.7%, and mean Conformal Index 0.71 and 0.68 with GrO and IPSA, respectively. IPSA plans had a higher mean homogeneity index (0.69 vs. 0.63, p<0.001) and lower volume of target receiving 150% (30.2% vs. 35.6%, p<0.001) and 200% (10.7% vs. 12.7%, p<0.001) of the prescription dose. Mean dose to urethra, rectum, and bladder were all significantly lower with IPSA (p<0.001). IPSA plans tended to be more reproducible, with smaller standard deviations for all measured parameters.

Conclusions

Plans generated using IPSA provide similar target coverage to those obtained using GrO but with lower dose to normal structures and greater dose homogeneity.

Keywords: High dose rate, Optimization, Prostate, Inverse planning, Brachytherapy

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 This work was presented in part at the May 2006 annual scientific meeting of the American Brachytherapy Society, Philadelphia, PA.

PII: S1538-4721(07)00252-8

doi:10.1016/j.brachy.2007.10.001

Brachytherapy
Volume 7, Issue 1 , Pages 12-16, January 2008

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