Radiobiological Model-Based Plan Evaluation for Patients Undergoing Radiotherapy Treatment

Radiotherapy treatment becoming essential in the treatment of most of the cancers. It is realised that technology is advancing rapidly which also impacted the advancement of radiotherapy techniques. With new modern techniques evolved with time, complexity as complementary attached to it. Modern techniques demand accuracy, knowledge of additional parameters and new approaches. Keeping in mind present thesis focused on efforts that how the radiotherapy treatment can be improved for the benefit of patients. Radiobiological models started to appear in 1980s since then it is continuously evolving. Medical physicist community is now understanding the importance of radiobiological models and many vendors started to incorporate radiobiological models with their treatment planning system. Still, most of the Medical physicist of the community hesitate to use radiobiological models because of uncertainty and complexity. Therefore, radiobiological models remained the topic of research. But with the efforts of researchers plenty of data have been produced with respect to biological models which is strengthening the reliability of these models. This work is motivated from the discussion during plan evaluation when one of the organ at risk (spinal cord) received dose beyond tolerance limit and it was impossible to achieve. The discussion moved from physical parameter based assessment to basic radiobiology of specific tissue of interest. It gives a kick, to study radiobiological models to handle complex scenarios during plan evaluation. Presently number of radiation oncologists are practicing altered fractionation depends on many clinical trials, changes in fractionation regimen drastically changes the treatment outcome. Therefore, if it is possible to understand the probability of outcome before it appears, it can lead in improvisation of treatment. There are number of biological models exist in literature and varies in terms of biological parameters. It is needed to choose appropriate biological model for better outcome and its validation before implementing in routine clinical practice. Present thesis work tried to answer doubts of radiobiological models and intended to bring in general practice.