Challenges in Monte Carlo Simulations as Clinical and Research Tool in Particle Therapy: A Review

Abstract

The use and interest in Monte Carlo (MC) techniques in the field of medical physics have been rapidly increasing in the past years. This is the case especially in particle therapy, where accurate simulations of different physics processes in complex patient geometries are crucial for a successful patient treatment and for many related research and development activities. Thanks to the detailed implementation of physics processes in any type of material, to the capability of tracking particles in 3D, and to the possibility of including the most important radiobiological effects, MC simulations have become an essential calculation tool not only for dose calculations but also for many other purposes, like the design and commissioning of novel clinical facilities, shielding and radiation protection, the commissioning of treatment planning systems, and prediction and interpretation of data for range monitoring strategies. MC simulations are starting to be more frequently used in clinical practice, especially in the form of specialized codes oriented to dose calculations that can be performed in short time. The use of general purpose MC codes is instead more devoted to research. Despite the increased use of MC simulations for patient treatments, the existing literature suggests that there are still a number of challenges to be faced in order to increase the accuracy of MC calculations for patient treatments. The goal of this review is to discuss some of these remaining challenges. Undoubtedly, it is a work for which a multidisciplinary approach is required. Here, we try to identify some of the aspects where the community involved in applied nuclear physics, radiation biophysics, and computing development can contribute to find solutions. We have selected four specific challenges: i) the development of models in MC to describe nuclear physics interactions, ii) modeling of radiobiological processes in MC simulations, iii) developments of MC-based treatment planning tools, and iv) developments of fast MC codes. For each of them, we describe the underlying problems, present selected examples of proposed solutions, and try to give recommendations for future research.

Localization of anatomical changes in patients during proton therapy with in‐beam PET monitoring: A voxel‐based morphometry approach exploiting Monte Carlo simulations

“…Another possibility is the usage of fast MC simulation codes, which are being more and more frequently used in clinical practice. 52…”

Coupling Radiation Transport and Track-Structure Simulations: Strategy Based on Analytical Formulas Representing DNA Damage Yields

“…In this work, we have analyzed the previously published comprehensive database of PARTRAC simulations on DNA damage induced by light ions [20,21]. Model cell nuclei were irradiated by 1 H, 4 He, 7 Li, 9 Be, 11 B, 12 C, 14 N, 16 O or 20 DSBs, DSB clusters and DSB sites were scored. From absolute numbers of the lesions and the deposited dose, damage yields per Gy per Gbp were calculated.…”

“…Radiation transport codes are a key tool for many research and practical applications dealing with radiation-matter interactions. Many codes exist, including FLUKA, Geant4, MCNP, PHITS or TOPAS [1][2][3][4][5]; recent reviews focused on radiotherapy applications can be found in [6,7]. In most cases a common issue has to be faced: The radiation field and the resulting dose distribution have to be captured at a rather large spatial scale, e.g., in a human body, in a high-energy physics detector, or in a shielding layer in a space habitat.…”

“…Its recent applications included a model that provided mechanistic interpretation for the biological effectiveness of neutrons[14,15], a model of radiation-induced bystander effects[26][27][28][29][30], or a study on radiation effects on mitochondrial DNA[31].In this work, we have analyzed the previously published comprehensive database of PARTRAC simulations on DNA damage induced by light ions[20,21]. Model cell nuclei were irradiated by 1 H,4 He,7 Li,9 Be, 11 B,12 C, 14 N,16 O or20 Ne ions at starting energies of 0.25, 0.5, 1, 2, 4, 8, 16, 32, 64, 128, 256 or 512 MeV/u. The ions were started fully stripped of electrons.…”

Charge identification of nuclear fragments with the FOOT Time-Of-Flight system

“…This quantity, needed to calculate biological dose and to predict treatment outcomes, demonstrates a complex dependency on several physical and biological parameters, among which the spectrum of nuclear fragments produced in interactions of the particle beam with the patient tissue [2][3][4]. To simulate the biological effect of these fragments and take it into account in particle therapy treatment planning, it is important to accurately model their production [5,6]. Differential cross section measurements for nuclear fragment production in thin targets are the most valuable for this purpose.…”