Evaluation of VMAT Planning Strategies for Prostate Patients with Bilateral Hip Prosthesis

To, David; Xhaferllari, Ilma; Liu, Manju; Liang, Jian; Knill, Cory; Nandalur, S.R.; Gustafson, Gary; Lack, Danielle

doi:10.1177/15330338211038490

Cited by 5 publications

(2 citation statements)

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“…The third plan was VMAT using 2 full arcs (clockwise and counterclockwise). The prosthesis region was avoided by applying a strict optimization constraint (<500 cGy to 10% volume) [15,31]. Dose to the prosthesis volume was assessed to evaluate the avoidance efficiency, because this criterion was not prioritized over target coverage during optimization.…”

Section: Treatment Planning and Robustness Evaluationmentioning

confidence: 99%

“…Therefore, beam arrangements that avoid the prosthesis region have been recommended to decrease uncertainties [14]. The current standard of RT practice for prostate cancer patients with hip prosthesis is volumetric modulated arc therapy (VMAT), which delivers the prescribed dose during a continuous rotation of the gantry around the isocenter, using prosthesis avoidance techniques, e.g., several partial arcs that could be cumbersome, and applying either avoidance sectors or avoidance optimization with full arcs [15][16][17][18][19][20]. PT has not been a feasible option so far due to beam interference with the prosthesis hardware.…”

Section: Introductionmentioning

confidence: 99%

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The Role of Proton Therapy for Prostate Cancer in the Setting of Hip Prosthesis

Moteabbed,

Bobić,

Paganetti

et al. 2024

Cancers

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Purpose: Given that the current standard of proton therapy (PT) for prostate cancer is through bilateral beams, this modality is typically avoided when it comes to treatment of patients with hip prosthesis. The purpose of this study was to evaluate whether novel PT methods, i.e., anterior proton beams and proton arc therapy (PArc), could be feasible options to treat this patient subpopulation. We evaluate PT methods in the context of dosimetry and robustness and compare with standard of practice volumetric modulated arc therapy (VMAT) to explore any potential benefits. Methods: Two PT and one VMAT treatment plans were retrospectively created for 10 patients who participated in a clinical trial with a weekly repeat CT (rCT) imaging component. All plans were robustly optimized and featured: (1) combination anterior oblique and lateral proton beams (AoL), (2) PArc, and (3) VMAT. All patients had hydrogel spacers in place, which enabled safe application of anterior proton beams. The planned dose was 70 Gy (RBE) to the entire prostate gland and 50 Gy (RBE) to the proximal seminal vesicles in 28 fractions. Along with plan dose–volume metrics, robustness to setup and interfractional variations were evaluated using the weekly rCT images. The linear energy transfer (LET)-weighted dose was evaluated for PArc plans to ensure urethra sparing given the typical high-LET region at the end of range. Results: Both PT methods were dosimetrically feasible and provided reduction of some key OAR metrics compared to VMAT except for penile bulb, while providing equally good target coverage. Significant differences in median rectum V35 (22–25%), penile bulb Dmean (5 Gy), rectum V61 (2%), right femoral head Dmean (5 Gy), and bladder V39 (4%) were found between PT and VMAT. All plans were equally robust to variations. LET-weighted dose in urethra was equivalent to the physical dose for PArc plans and hence no added urethral toxicity was expected. Conclusions: PT for treatment of prostate cancer patients with hip prosthesis is feasible and equivalent or potentially superior to VMAT in quality in some cases. The choice of radiotherapy regimen can be personalized based on patient characteristics to achieve the best treatment outcome.

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Section: Treatment Planning and Robustness Evaluationmentioning

confidence: 99%