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Efficient Proton Arc Therapy with Column-Generation Planning

M Chen*, X Gu, W Lu, UT Southwestern Medical Center, Dallas, TX

Presentations

(Sunday, 7/12/2020)   [Eastern Time (GMT-4)]

Room: AAPM ePoster Library

Purpose:
Proton arc therapy (PAT) has the potential benefit of improved dose homogeneity and normal tissue sparing. However, conventional PAT plans could be very delivery-inefficient due to an enormous number of spots and energy switches required. In this work, we proposed a novel planning scheme to achieve high quality PAT plans with efficient delivery.

Methods:
We formulated the efficient PAT plan optimization problem as to find a minimal set of energies to approach the dose objectives and solved the optimization using column generation (CG) that progressively improves the plan quality. We used a Head&Neck case to study the proposed PAT-CG scheme and compared the results with those of using IMPT and conventional PAT (PAT-full). All plans were optimized with the PTV objective of 100Gy and underdose penalty being 10x overdose penalty. PTV dose-range (PTV-DR) and maximum OAR dose (OAR-D2) were used as plan quality metrics, and the inverse ratio of delivery time to that of IMPT was used to measure the delivery efficiency.

Results:
CG-based PAT plans achieved comparable plan qualities to those of PAT-full within 4 energy layers (PAT-CG4) and were much better than the IMPT plans. The PTV-DRs were 28.75Gy, 26.42Gy, 24.03Gy, and the OAR-D2s were 86.50Gy, 33.56Gy and 32.59Gy, for IMPT, PAT-CG4 and PAT-full, respectively. The delivery efficiency of PAT-CG4 and PAT-full were 84% and 19%, respectively. PAT-CG4 improved efficiency by four times without sacrificing plan quality compared to PAT-full.

Conclusion:
PAT is known to improve plan quality at the cost of long treatment time. With the novel energy optimization algorithm, it allows time-minimization in spots and energy switches while maintaining the PAT plan quality. The proposed method may pave the way to clinical implementation of PAT.

Download ePoster [PDF]

Funding Support, Disclosures, and Conflict of Interest: This work was supported in part by NIH grants (R01 CA235723, R01 CA218402).

Keywords

Optimization, Treatment Planning

Taxonomy

TH- External Beam- Particle/high LET therapy: Proton therapy – treatment planning/virtual clinical studies

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