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Updated: May 15, 2026
08:34
Proton Therapy Delivery and Its Clinical Application in Select Solid Tumor Malignancies
Published on: February 6, 2019
Impact of variable RBE on proton fractionation
Alexandru Dasu1, Iuliana Toma-Dasu
1Department of Radiation Physics UHL, County Council of Östergötland, Linköping, Sweden. alexandru.dasu@lio.se
Medical Physics
|January 10, 2013
Summary
Variable proton relative biological effectiveness (RBE) significantly impacts dose fractionation in radiotherapy. Accurate RBE accounting is crucial for predicting treatment outcomes, especially for tumors with low α∕β and low doses per fraction.
Area of Science:
- Radiation Oncology
- Medical Physics
- Radiobiology
Background:
- Proton therapy utilizes a generic relative biological effectiveness (RBE) of 1.1 for dose calculations.
- Experimental data indicates proton RBE varies with tissue type, dose, and linear energy transfer (LET).
Purpose of the Study:
- To investigate the influence of variable proton RBE on dose fractionation in clinical scenarios.
- To compare predictions using a variable RBE with a generic RBE and existing clinical data.
Main Methods:
- Employed an analytical expression of the linear-quadratic (LQ) model incorporating LET and α∕β dependence for proton simulations.
- Performed calculations for various LET values and fractionation sensitivities, simulating treatments for head and neck and prostate tumors.
Main Results:
- A generic RBE of 1.1 is adequate for high-throughput tissues with low LET radiation.
- Variable RBE models show significant differences for tissues with low α∕β and low doses per fraction, aligning better with clinical outcomes.
- Accurate accounting for proton radiobiological effectiveness is highlighted as important, potentially differing from photon study findings.
Conclusions:
- The LET dependence of RBE strongly influences the predicted efficacy of fractionated proton radiotherapy.
- Fractionation sensitivity and fractional dose modulate the impact of variable RBE, necessitating precise analysis.
- Caution is advised when altering clinical fractionation or interpreting results from proton therapy studies.
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