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An Efficient and Robust Algorithm for Catheter Optimization in High Dose Rate Brachytherapy

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E Poulin

E Poulin1-4*, C Collins Fekete1-4, M Letourneau1-4, A Fenster2, J Pouliot3, L Beaulieu1-4, (1) Universite Laval, Quebec, Qc, (2) Robarts Research Institute, London, ON, (3) UC San Francisco, San Francisco, CA, (4) Centre Hospitalier Univ de Quebec, Quebec, QC

SU-D-108-1 Sunday 2:05PM - 3:00PM Room: 108

Purpose: We present a simple, fast and robust method to optimize both the number and position of catheters in interstitial high dose rate (HDR) brachytherapy, using a modified version of the Centroidal Voronoi Tessellations algorithm.

Methods: 8 HDR clinical cases were chosen randomly for both prostate and breast to test our method. The dose distributions were obtained using a research version of IPSA. Clinically relevant dosimetric parameters were computed to evaluate our method and test the robustness. For the prostate, plans generated from our method were compared to the clinical cases with 17 catheters. The efficiency of the algorithm was also tested with breast cases. The robustness of the method to implantation error was evaluated using 100 iterations and an error of 1, 2, 3, or 5 mm to each catheter of the plan.

Results: A better or equal prostate V100 was obtained with as few as 12 catheters when compared with the clinical case. Plans with 9 or less catheters would not be clinically acceptable. Plans with 17 catheters were better than the clinical plans with the same number of catheters. The computation time to obtain 10 complete treatment plans ranging from 9 to 18 catheters, with the corresponding dosimetric indices, was 90 s. For the breast, on average, the RTOG recommendations would be satisfied with 12 catheters. Plans with 9 or less catheters would not be clinically acceptable in terms of V100, DHI and D90. Implantation errors up to 3 mm were acceptable.

Conclusion: We have devised a simple, fast, robust and efficient method to optimize the number and position of catheters in HDR brachytherapy. Ultimately, this catheter optimization algorithm could be coupled with a 3D ultrasound system to allow real-time guidance and planning for any interstitial brachytherapy sites.

Funding Support, Disclosures, and Conflict of Interest: Funding support: CIHR and NSERC

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