Creating clinically competitive FLASH proton therapy treatment plans
Nathalie Lovgren,
United Kingdom
PO-1685
Abstract
Creating clinically competitive FLASH proton therapy treatment plans
Authors: Nathalie Lovgren1, Kristoffer Petersson1, Rudi Labarbe2, Lucian Hotoiu2, Ingrid Fagerström Kristensen3
1University of Oxford, Oncology, Oxford, United Kingdom; 2Ion Beam Applications (IBA), IBA Research, Louvain-la-Neuve, Belgium; 3Skåne University Hospital, Oncology, Lund, Sweden
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Purpose or Objective
FLASH proton therapy (FLASH-PT) aims to use ultra-high dose rates (≥ 40 Gy/s) to induce a normal tissue sparing effect whilst maintaining the anti-tumour effectiveness of conventional dose rates. The beam delivery, dose rates, and fractionation schemes for FLASH-PT differ from standard radiotherapy. Hence, no guidelines exist regarding the development of treatment plans for this novel technique. The purpose of this study is to determine if FLASH-PT treatment plans can be developed and if the in silico results are comparable to the treatment plans produced for standard radiotherapy.
Material and Methods
FLASH-PT and IMPT treatment plans were created using a novel research version of the MIROpt TPS developed by Ion Beam Applications SA from the open source version of UCLouvain. To produce conformal FLASH-PT plans the beam setup involved monoenergetic spot-scanned protons traversing through a conformal energy filter, a range shifter, and an aperture. The treatment plans were created for nine patient cases of bone (3), brain (3), and lung (3) metastases, all previously clinically treated with 3DCRT or VMAT. A dose rate of ≥ 40 Gy/s was included as an optimisation criterion for all FLASH-PT treatment plans for each patient case. Dose volume histograms (DVHs), boxplots, and the Wilcoxon Rank Sum Test were used to compare the FLASH-PT plans to the 3DCRT/VMAT and optimised IMPT plans. The statistical test was carried out with a 5% significance level and using DVH parameters V100%, V95%, V50%, D99%, D95%, and D2% for target and body structures.
Results
The qualitative and statistical comparisons yielded no significant differences between the optimised FLASH-PT plans and the clinical 3DCRT/VMAT and optimised IMPT plans.
Conclusion
The FLASH-PT treatment plans created in this study produced in silico results comparable to those of clinically competitive treatment plans. Future work involves the verification of the calculated dose against delivered dose and dose rate, to ensure that the produced treatment plans can be delivered safely and accurately, confirming the feasibility of the clinical implementation of conformal FLASH-PT.