Work

Reducing the dose delivered to major intracranial blood vessels in brain radiotherapy using spot‐scanning proton arc therapy

Year: 2026

Type: article

Abstract: Background Glioblastoma (GBM) patients have poor clinical prognoses, which may partially be explainable by correlations between radiation‐induced killing of circulating blood cells (CBCs) and worse clinical outcomes. Proton radiotherapy is currently delivered via intensity‐modulated proton therapy (IMPT), for which the target is irradiated from a few different angles. Spot‐scanning proton arc therapy (SPArc), for which the target is irradiated from arc trajectories, is associated with dosimetric benefits, and the first SPArc treatments of head‐and‐neck cancer patients have now been reported. However, since SPArc increases the low‐dose bath, concerns have been raised about potentially higher killing of CBC. Purpose This study aims to evaluate and compare blood vessel dose and dose‐averaged linear energy transfer (LET d ) distributions between IMPT and SPArc, with and without blood vessel sparing, in patients with GBM. Methods For 10 GBM patients, patient‐specific cerebrovasculature models were developed, and IMPT and SPArc treatment plans were created according to current clinical standards (IMPT Conv and SPArc Conv ) and with sparing of delineated blood vessels (IMPT Sparing and SPArc Sparing ) for every patient. Dose and LET d distributions were then compared across all treatment plans. Results While treatment plans maintained comparable target coverage, blood vessel sparing significantly reduced the mean dose to delineated blood vessels, with values of 6.5 ± 2.9 Gy(RBE) for IMPT Conv , 5.3 ± 2.3 Gy(RBE) for IMPT Sparing , 5.6 ± 2.2 Gy(RBE) for SPArc Conv , and 3.8 ± 1.6 Gy(RBE) for SPArc Sparing . The dose within the 10% of blood vessel volume receiving the highest dose (D 10% ) was 29.5 ± 13.4 Gy(RBE) for IMPT Conv , 23.2 ± 11.0 Gy(RBE) for IMPT Sparing , 24.5 ± 12.6 Gy(RBE) for SPArc Conv , and 13.4 ± 8.7 Gy(RBE) for SPArc Sparing . Conclusions Implementation of blood vessel sparing resulted in successful reductions in blood vessel dose metrics while preserving target coverage, and SPArc further reduced blood vessel dose metrics compared with IMPT, with the potential to reduce radiation‐induced lymphopenia and improve clinical outcomes.

Source: Journal of Applied Clinical Medical Physics

DOI: 10.1002/acm2.70780

Authors: Peilin Liu, Sebastian Tattenberg, Xiaoda Cong, Peter Y. Chen, Xuanfeng Ding, Abdelkhalek Hammi