Barbara Caccia

MedLinac2: a GEANT4 based software package for radiotherapy

Dose distribution evaluation in oncological radiotherapy treatments is an outstanding problem that requires sophisticated computing technologies to optimize the clinical results (i.e. increase the dose to the tumour and reduce the dose to the healthy tissues). Nowdays, dose calculation algorithms based on the Monte Carlo method are generally regarded as the most accurate tools for radiotherapy. The flexibility of the GEANT4 (GEometry ANd Tracking) Monte Carlo particle transport simulation code allows a wide range of applications, from high-energy to medical physics. In order to disseminate and encourage the use of Monte Carlo method in oncological radiotherapy, a software package based on the GEANT4 Monte Carlo toolkit has been developed. The developed package (MedLinac2) allows to simulate in an adequate flexible way a linear accelerator for radiotherapy and to evaluate the dose distributions.

The influence of dose rate and oxygen on the irradiation induced degradation in ethylene-propylene rubber

Abstract The ESR technique was used to study the influence of dose rate and oxygen on the radiation induced effects on an ethylene-propylene loaded with antioxidant characterized by an NH functional group. It was shown that the oxidative degradation takes place during irradiation and the oxidation products increase with decreasing dose rate [H. Kashiwabara and T. Seguchi, in: Radiation Processing of Polymers, eds. A. Singh and J. Silverman (Hanser, 1992)].

Fast and high temperature hyperthermia coupled with radiotherapy as a possible new treatment for glioblastoma

BackgroundA new transcranial focused ultrasound device has been developed that can induce hyperthermia in a large tissue volume. The purpose of this work is to investigate theoretically how glioblastoma multiforme (GBM) can be effectively treated by combining the fast hyperthermia generated by this focused ultrasound device with external beam radiotherapy.Methods/DesignTo investigate the effect of tumor growth, we have developed a mathematical description of GBM proliferation and diffusion in the context of reaction–diffusion theory. In addition, we have formulated equations describing the impact of radiotherapy and heat on GBM in the reaction–diffusion equation, including tumor regrowth by stem cells. This formulation has been used to predict the effectiveness of the combination treatment for a realistic focused ultrasound heating scenario.Our results show that patient survival could be significantly improved by this combined treatment modality.DiscussionHigh priority should be given to experiments to validate the therapeutic benefit predicted by our model.

A computational tool for evaluating HIFU safety

BACKGROUND High Intensity Focused Ultrasound (HIFU) is a noninvasive treatment for therapeutic applications, in particular the treatment of either benign or malignant tumor lesions. HIFU treatment is based on the power of a focused ultrasound beam to locally heat biological tissues over a necrotic level with minimal impact on the surrounding tissues. Therapies based on HIFU are becoming widely spread in the panorama of options offered by the Health Care System. Consequently, there is an ever increasing need to standardise quality assurance protocols and to develop computational tools to evaluate the output of clinical HIFU devices and ensuring safe delivery of HIFU treatment. AIMS Goal of this study is the development of a computational tool for HIFU ablation therapy to assure safety of the patient and effectiveness of the treatment. RESULTS The simulated results provide information about the behaviour of the focalized ultrasound in their interaction with different biological tissues. CONCLUSIONS Numerical simulation represents a useful approach to predict the heath deposition and, consequently, to assess the safety and effectiveness of HIFU devices.

Validation of Geant4 Nuclear Reaction Models for Hadron Therapy and Preliminary Results with BLOB

Reliable nuclear fragmentation models are of utmost importance in hadron therapy, where Monte Carlo (MC) simulations are used to compute the input parameters of the treatment planning software, to validate the deposited dose calculation, to evaluate the biological effectiveness of the radiation, to correlate the \( \beta + \) emitters production in the patient body with the delivered dose, and to allow a non-invasive treatment verification. Despite of its large use, the models implemented in Geant4 have shown severe limitations in reproducing the measured secondaries yields in ions interaction below 100 MeV/A, in term of production rates, angular and energy distributions. We present a benchmark of the Geant4 models with double-differential cross section of the secondary fragments produced in the \( ^{12} {\text{C}} \) fragmentation at 62 MeV/A on thin carbon target. Such a benchmark includes the recently implemented model “Liege Intranuclear Cascade’’. Moreover, we present the preliminary results, obtained in simulating the same interaction, with the “Boltzmann-Langevin One Body’’ model (BLOB). BLOB is a semiclassical one-body approaches to solve the Boltzmann-Langevin equation. It includes a mean-field propagation term, on the basis of an effective interaction. In addition to the mean field term, BLOB introduces fluctuations in full phase space through a modified collision term where nucleon-nucleon correlations are explicitly involved. It has been developed to simulate the heavy ion interactions in the Fermi-energy regime. In this work, we show the BLOB capabilities in describing \( ^{12} {\text{C}} \) fragmentation, in the perspective of a direct implementation in Geant4. Monte Carlo simulation, nuclear interaction, nuclear fragmentation, hadron therapy.

EURADOS intercomparison exercise on Monte Carlo modelling of a medical linear accelerator

BACKGROUND In radiotherapy, Monte Carlo (MC) methods are considered a gold standard to calculate accurate dose distributions, particularly in heterogeneous tissues. EURADOS organized an international comparison with six participants applying different MC models to a real medical linear accelerator and to one homogeneous and four heterogeneous dosimetric phantoms. AIMS The aim of this exercise was to identify, by comparison of different MC models with a complete experimental dataset, critical aspects useful for MC users to build and calibrate a simulation and perform a dosimetric analysis. RESULTS Results show on average a good agreement between simulated and experimental data. However, some significant differences have been observed especially in presence of heterogeneities. Moreover, the results are critically dependent on the different choices of the initial electron source parameters. CONCLUSIONS This intercomparison allowed the participants to identify some critical issues in MC modelling of a medical linear accelerator. Therefore, the complete experimental dataset assembled for this intercomparison will be available to all the MC users, thus providing them an opportunity to build and calibrate a model for a real medical linear accelerator.