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Sci—Thurs AM: YIS—02: Optimizing Number and Position of Catheters within Inverse Planning Simulated Annealing (IPSA) for Prostate and Breast High Dose Rate Brachytherapy
Author(s) -
Ayotte G,
D'Amours M,
Aubin S,
Lessard É,
Pouliot J,
Beaulieu L
Publication year - 2009
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3244162
Subject(s) - brachytherapy , prostate , medicine , prostate brachytherapy , catheter , radiation treatment planning , nuclear medicine , radiology , urology , surgery , radiation therapy , cancer
In clinical high dose rate (HDR) brachytherapy for prostate and breast, catheters are generally implanted using a template, without considering precise tumor size and shape. In this work, we present a method to optimize the number and position of catheters before the implantation stage. Methods: A research version of IPSA was modified to gradually remove uniformly distributed catheters on target volume, until the desired number of catheters is reached. Criterion for removal is based on the fraction of total treatment time attributable to each catheter. We have applied this method to a clinical prostate case implanted with 18 catheters and a breast implant of 21 catheters. For prostate case, some chosen catheters were fixed to take into account the low, but essential treatment time needed near the urethra. Results: For the studied prostate case, the cost function value is reduced for optimizations with 18 catheters down to 15, compared with the clinical plan. Bladder and urethra receive lower dose for all plans and rectum V75 is independent of the number of catheters. For the breast case, a plan with 19 catheters leads to a similar cost function value than the clinical case and optimized plans lead to a better skin protection, down to 13 catheters. Conclusion: We have devised a simple and efficient method to optimize the locations and number of catheters which could be extended to all types of interstitial HDR brachytherapy. The results indicate that it is possible to obtain clinically optimal treatment plans with fewer catheters.