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SU‐F‐T‐15: Evaluation of 192Ir, 60Co and 169Yb Sources for High Dose Rate Prostate Brachytherapy Inverse Planning Using An Interior Point Constraint Generation Algorithm
Author(s) -
Mok Tsze Chung E,
Safigholi H,
Nicolae A,
Davidson M,
Ravi A,
Aleman D,
Song W
Publication year - 2016
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 - 10.1118/1.4956149
Subject(s) - brachytherapy , rectum , prostate , medicine , prostate cancer , nuclear medicine , urethra , urology , radiation treatment planning , volume (thermodynamics) , algorithm , mathematics , physics , radiation therapy , radiology , cancer , surgery , quantum mechanics
Purpose: The effectiveness of using a combination of three sources, 60 Co, 192 Ir and 169 Yb, is analyzed. Different combinations are compared against a single 192 Ir source on prostate cancer cases. A novel inverse planning interior point algorithm is developed in‐house to generate the treatment plans. Methods: Thirteen prostate cancer patients are separated into two groups: Group A includes eight patients with the prostate as target volume, while group B consists of four patients with a boost nodule inside the prostate that is assigned 150% of the prescription dose. The mean target volume is 35.7±9.3cc and 30.6±8.5cc for groups A and B, respectively. All patients are treated with each source individually, then with paired sources, and finally with all three sources. To compare the results, boost volume V150 and D90, urethra Dmax and D10, and rectum Dmax and V80 are evaluated. For fair comparison, all plans are normalized to a uniform V100=100. Results: Overall, double‐ and triple‐source plans were better than single‐source plans. The triple‐source plans resulted in an average decrease of 21.7% and 1.5% in urethra Dmax and D10, respectively, and 8.0% and 0.8% in rectum Dmax and V80, respectively, for group A. For group B, boost volume V150 and D90 increased by 4.7% and 3.0%, respectively, while keeping similar dose delivered to the urethra and rectum. 60 Co and 192 Ir produced better plans than their counterparts in the double‐source category, whereas 60 Co produced more favorable results than the remaining individual sources. Conclusion: This study demonstrates the potential advantage of using a combination of two or three sources, reflected in dose reduction to organs‐at‐risk and more conformal dose to the target. three sources, reflected in dose reduction to organs‐at‐risk and more conformal dose to the target. Our results show that 60 Co, 192 Ir and 169 Yb produce the best plans when used simultaneously and can thus be an alternative to 192 Ir‐only in high‐dose‐rate prostate brachytherapy.