LETd Optimization Verification With an SOI Microdosimeter

V A Pan; L T Tran; T Madden; B Clasie; H Kooy; A B Rosenfeld; N Depauw

doi:10.1016/j.ijrobp.2023.12.036

LET_d Optimization Verification With an SOI Microdosimeter

Int J Radiat Oncol Biol Phys. 2024 Jan 31:S0360-3016(23)08310-4. doi: 10.1016/j.ijrobp.2023.12.036. Online ahead of print.

Authors

V A Pan¹, L T Tran², T Madden³, B Clasie³, H Kooy³, A B Rosenfeld², N Depauw³

Affiliations

¹ Centre for Medical and Radiation Physics, University of Wollongong, Wollongong, NSW, Australia. Electronic address: vp881@uowmail.edu.au.
² Centre for Medical and Radiation Physics, University of Wollongong, Wollongong, NSW, Australia.
³ Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.

PMID: 38300188
DOI: 10.1016/j.ijrobp.2023.12.036

Abstract

Purpose: A first of its kind experimental verification of dose-averaged linear energy transfer (LET_d) optimized treatment plans for proton therapy has been carried out using a silicon-on-insulator microdosimeter at the Massachusetts General Hospital (MGH), Boston, USA.

Methods and materials: Three clinical treatment plans of a typical ependymoma structure set were designed using the standard clinical approach, the proposed protocol approach, and a one-field approach. The plans were then reoptimized to reduce the LET_d-weighted dose in the brain stem. All six plans were delivered in a solid water phantom and the experimental y_D‾ measured.

Results: After LET_d optimization, a reduction in y_D‾ was found within the brain stem by an average of 12%, 19%, and 4% for the clinical, protocol, and one-field plans, respectively, while maintaining adequate coverage of the tumor structure. The experimental LET_d-weighted doses were in agreement with the treatment planning system calculations and Monte Carlo simulations and reinforced the improvement of the optimization.

Conclusions: This work demonstrates the first experimental verification of the clinical implementation of LET_d optimization for patient treatment with proton therapy.