Integration of microdosimetry into treatment planning systems using look-up tables (LUT): A proof-of-concept

Microdosimetry provides a statistical, measurable description of energy deposition at the sub-cellular level, directly linked to biological effectiveness. In recent years its application to proton therapy has shown promising improvements in the accuracy of radiobiological modelling. This paper introduces a novel approach for integrating microdosimetric quantities into the treatment planning process.

This study aims to demonstrate the feasibility of a method for incorporating microdosimetric quantities into TPS, through the creation of look-up tables (LUT) that account for the stochastic nature of energy deposition occurring during a proton treatment irradiation.

This work provides a preliminary set of LUT that relate the kinetic energy of incoming protons to the first-order stochastic means obtained from the corresponding microdosimetric spectra to proton kinetic energy. Such LUT are pre-produced via Monte Carlo simulations with sub-micrometre precision and can be immediately implemented into commercial TPSs. The resulting quantities are validated against complete Monte Carlo simulations, showing an agreement within 1 keV/µm for y¯_F, y^∗, and y¯_D from the entrance region through the 20 % distal fall-off, and within 3 keV/µm at greater depths. Applying the MKM model to y^∗, this process enables a microdosimetric RBE prediction with an agreement exceeding 98.5 %.

This work represents a promising initial step toward the successful implementation of microdosimetry in routine clinical practice. Establishing a standardized approach will enhance consistency and comparability across institutions.