Rapid RBE-Weighted Proton Radiation Dosimetry Risk Assessment

Abstract

Proton therapy dose is affected by relative biological effectiveness differently than X-ray therapies. The current clinically accepted weighting factor is 1.1 at all positions along the depth-dose profile. However, the relative biological effectiveness correlates with the linear energy transfer, cell or tissue type, and the dose per fraction causing variation of relative biological effectiveness along the depth-dose profile. In this article, we present a simple relative biological effectiveness-weighted treatment planning risk assessment algorithm in 2-dimensions and compare the results with those derived using the standard relative biological effectiveness of 1.1. The isodose distribution profiles for beams were accomplished using matrices that represent coplanar intersecting beams. These matrices were combined and contoured using MATLAB to achieve the distribution of dose. There are some important differences in dose distribution between the dose profiles resulting from the use of relative biological effectiveness ¼ 1.1 and the empirically derived depth-dependent values of relative biological effectiveness. Significant hot spots of up to twice the intended dose are indicated in some beam configurations. This simple and rapid risk analysis could quickly evaluate the safety of various dose delivery schema.

National Cancer Institute Workshop on Proton Therapy for Children: Considerations Regarding Brainstem Injury

“…Solutions to this include more biologic research, evolving radiation planning approaches, and software development to show biologic dose visually in a format that is easier to understand and analyze. [73] As well, the field needs to monitor limited-term morbidities, especially as we introduce IMPT routinely in managing pediatric brain tumors. Inter-patient variability might be substantial, affecting both proton and photon treatments and thus making it difficult to identify effects solely caused by elevated RBE values.…”

Radiation-agent combinations for glioblastoma: challenges in drug development and future considerations

“…Radiomics enables high-output extraction of medical image quantitative features, providing a comprehensive non-invasive assessment of tumor phenotype [42]. Radiomics has spurred interest in near-term research initiatives that include photon and particle radiotherapy delivery platforms driven by treatment planning software utilizing (a) biologic rather than physical dose [43], (b) grid therapy [44], and (c) avoidance algorithms for eloquent brain [45]. How best to integrate radiomics into clinical trials remains under study.…”

Moving Forward in the Next Decade: Radiation Oncology Sciences for Patient-Centered Cancer Care

“…Therefore, the initial proposed mechanisms may not be what is operative with time. That the relative biological effectiveness (RBE) at the end or edge of a particle beam matters greatly for potential toxicity with proton therapy was recognized after treatments had been administered for years ( 8 ). Our future is now exceptional technology, induced biological changes and multimodality treatments with regulatory ( https://www.fda.gov/medical-devices/premarket-submissions/premarket-notification-510k# ), and clinical implementation that require broad understanding of safety and short- and long-term efficacy as they move from research into routine clinical practice.…”