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Updated: Jun 14, 2026
06:08
Use of a Linear Accelerator for Conducting In Vitro Radiobiology Experiments
Published on: May 26, 2019
Dose-rate effects in external beam radiotherapy redux.
C Clifton Ling1, Leo E Gerweck, Marco Zaider
1Varian Medical Systems, Palo Alto, CA, USA. lingc@mskcc.org
Summary
The dose-rate effect in radiotherapy is crucial, especially in hypofractionated treatments. Late-responding normal tissues are more sensitive to dose-rate variations than tumors, impacting overall radio-response.
Area of Science:
- Radiation oncology
- Radiobiology
- Medical physics
Background:
- External beam radiotherapy advancements necessitate re-evaluating dose-rate effects.
- Dose-rate influences radio-response through factors like DNA repair and tissue sensitivity.
Purpose of the Study:
- To review and analyze the impact of dose-rate on radio-response in radiotherapy.
- To estimate the influence of overall treatment time on clinical outcomes using radiobiological models.
Main Methods:
- Comprehensive literature review on dose-rate effects.
- Application of radiobiological principles and the linear-quadratic (LQ) model.
- Estimation of dose-rate influence on tumor and normal tissue response.
Main Results:
- Dose-rate effects are significant in hypofractionated treatments with large doses per fraction.
- Late-reacting normal tissues show higher sensitivity to dose-rate changes compared to tumors and early-reacting tissues.
- In conventional fractionation (1.8-2Gy/fraction), dose-rate influence is minimal.
Conclusions:
- Overall beam-on-time, not average or instantaneous dose-rate, governs the dose-rate effect in external beam radiotherapy.
- Clinical strategies should consider dose-rate implications, particularly for late-responding tissues in hypofractionated regimens.
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