Robust, accurate and patient-specific treatment planning for proton therapy

Barragan Montero, Ana Maria [UCL]

The survival statistics for cancer patients treated with radiation therapy using photon beams show that many treatments fail due to poor tumour local control (TLC). A potential solution would be to increase the target dose, but this often entails high toxicity in the nearby healthy tissue. Unlike photons, protons release most of their energy at the end of their path (the so-called Bragg peak), reducing the dose to healthy tissue, which might be the key for safe dose escalation. Moreover, functional images can reveal spatial heterogeneity in the tumor radioresistance pattern and therefore allow for improved targeting (dose painting) and possibly enhanced TLC. In this context, special care must be taken to accurately model the possible uncertainties in the position of the Bragg peak, since they can strongly deteriorate treatment quality, especially in very heterogeneous dose distributions as in dose painting plans. In this thesis, we investigated the use of the most advanced techniques, such as Monte Carlo dose calculation and robust optimization, to ensure accurate and robust planning for (dose painted) proton therapy treatments.