Radiobiological Models in Brachytherapy Treatment Planning and Evaluation
Z Chen*, DJ Carlson*, Yale Univ. School of Medicine, New Haven, CTTH-C-108-1 Thursday 10:30AM - 11:25AM Room: 108
Brachytherapy utilizes a multitude of radioactive sources and treatment techniques that often exhibit drastically different spatial and temporal dose delivery patterns from one another and from external beam radiotherapy. Typical photon energies vary from 0.02 MeV to 1 MeV and decay half-lives vary from days to years. Treatments can consist of single-fraction continuous low-dose-rate irradiations over a period of days or months to multi-fraction high-dose-rate irradiations of different dose fractionations. The clinical impact of such diverse spatial-temporal variations cannot be adequately assessed using traditional physical dose-based indices alone because these indices do not take into account the complex interplay between the dynamics of dose delivery and the biological response of the irradiated cells. Radiobiological models that capture the interacting effects of dose delivery with cellular biology can potentially provide a useful clinical tool for comparing and optimizing the relative clinical effectiveness of different brachytherapy treatment strategies. These models have been used increasingly by clinical medical physicists over the last decade in research settings. Currently, there are several different models presented in the literature with a range of applications and limitations. Information on model parameters, uncertainties, and their impact on model predictions are also scattered in the literature. The primary goal of this educational course is to provide a comprehensive review of existing radiobiological models and parameters, and their use in the evaluation of selected brachytherapy modalities. Particular emphasis will be placed on discussion of model limitations that may hinder the proper interpretation of model predictions and practical implementation.
The learning objectives are:
1. To understand the rationale and basis of existing radiobiological models used in the evaluation of brachytherapy treatments
2. To recognize the underlying assumptions and limitations of existing models and their proper application in the relative comparison of competing brachytherapy modalities
3. To be aware of the pitfalls regarding the selection, use, and interpretation of radiobiological models in treatment planning and evaluation
Funding Support, Disclosures, and Conflict of Interest: ZC would like to acknowledge partial support of NIH grant R01 CA134627