Radiobiological Outcomes, Microdosimetric Evaluations and Monte Carlo Predictions in Eye Proton Therapy

Abstract

CATANA (Centro di AdroTerapia ed Applicazioni Nucleari Avanzate) was the first Italian protontherapy facility dedicated to the treatment of ocular neoplastic pathologies. It is in operation at the LNS Laboratories of the Italian Institute for Nuclear Physics (INFN-LNS) and to date, 500 patients have been successfully treated. Even though proton therapy has demonstrated success in clinical settings, there is still a need for more accurate models because they are crucial for the estimation of clinically relevant RBE values. Since RBE can vary depending on several physical and biological parameters, there is a clear need for more experimental data to generate predictions. Establishing a database of cell survival experiments is therefore useful to accurately predict the effects of irradiations on both cancerous and normal tissue. The main aim of this work was to compare RBE values obtained from in-vitro experimental data with predictions made by the LEM II (Local Effect Model), Monte Carlo approaches, and semi-empirical models based on LET experimental measurements. For this purpose, the 92.1 uveal melanoma and ARPE-19 cells derived from normal retinal pigmented epithelium were selected and irradiated in the middle of clinical SOBP of the CATANA proton therapy facility. The remarkable results show the potentiality of using microdosimetric spectrum, Monte Carlo simulations and LEM model to predict not only the RBE but also the survival curves.

Non-Cancer Effects following Ionizing Irradiation Involving the Eye and Orbit

“…For example, the mean RBE value of 1.1 for protons has been accepted for practical clinical purposes for years but is currently challenged due to rare unexplained toxicities and the rapid expansion of proton facilities worldwide [ 5 ]. The complications associated with the known increase in the RBE towards the distal part of the spread-out Bragg peak (SOBP) and the inherent risk associated with it have led to microdosimetric in silico or experimental approaches and have shown significant variations along the beam path [ 6 ]. Numerous clinical and translational studies are being performed to assess the impact of RBE on outcomes.…”

Applications of Medical Physics

“…In the frame of eye proton therapy optimization for personalized treatments, Petringa et al [4] compare Relative Biological Effectiveness (RBE) values obtained from in vitro experimental data with predictions made by the Local Effect Model, Monte Carlo approaches, and semi-empirical models based on Linear Energy Transfer (LET) experimental measurements. Their results evidence how a Treatment Planning System based on an RBE and LET prediction could improve the estimation of the radiobiological response of the treated neoplasia as well as the surrounding healthy tissues.…”