Thesis

A new concept of proton therapy treatment planning based on nanodosimetric ionization detail.

• Call:

  ProtoTera Call 2021/2

• Academic Year:

  2021

• Supervisor:

  Ana Belchior

• Co-Supervisor:

  Reinhard Schulte

• Host Institution:

  C2TN - Centro de Ciências e Tecnologias Nucleares

• Granting Degree Institution:

  Instituto Superior Técnico (Universidade de Lisboa)

• Typology:

  Mixed

• Abroad Institution:

  Instituto Superior Técnico (Universidade de Lisboa)

• Abroad Supervisor:

  Antoni Rucinski

• Abstract:

  As the number of patients treated with proton therapy has increased, unexpected late effects have been observed [1]. Side effects could be caused by uncertainties in the relative biological effectiveness (RBE) of proton stopping in organs at risk. A constant RBE of 1.1 is still accepted in clinical practice, but experimental evidence shows that RBE varies with LET, fraction size, and biological endpoint. Experimentally measured RBE values across the spread-out Bragg peak can be as high as 1.7 [2]. The DNA damage caused by particles with higher LET is more complex and more difficult to repair. Rather than continuing with a constant RBE of 1.1, we propose a novel nanodosimetric approach independent of RBE. This project aims to study a novel treatment planning concept based on nanodosimetry. To accomplish this, we will study the distribution of ionization along particle tracks in small target volumes of DNA size both experimentally with a low-pressure gas-based nanodosimeter and with Monte Carlo track structure simulations, using the Geant4-DNA based TOPAS-nBio program. We will develop a novel ionization detail formalism and incorporate it in proton treatment planning systems. We will then systematically compare the normal tissue completion probability predicted with this approach to LET/RBE based planning techniques. Dr. Antoni Rucinski, Co-supervisor at the Krakow Centre for Proton Therapy, will guide me in the use of Monte Carlo based proton treatment planning. At Loma Linda University, Co-Supervisor Prof. Reinhard Schulte will introduce me to the concept of ID based treatment planning and TOPAS-nBio to calculate ID parameters. C2TN's supervisor in Lisbon, Dr. Ana Belchior, will provide overall guidance for the dissertation throughout the duration of the working programme. Close cooperation among the supervisors will contribute to achieving the project objectives and provide technology and knowledge transfer to future proton facilities in Portugal.