Simulations

Abstract

Simulations are important in hadron therapy for tumors located in areas that do not allow invasive procedures, such as inoperable neck carcinoma (see Fig. 1.12), uveal melanoma and pediatric tumors. The simulations act as a precision instrument that can be employed in these cases [15, 17]. Simulations using the Monte Carlo method can take into account all of the physical effects caused by the interaction of the particle beam with body tissue. The Monte Carlo code Geant4 (geometry and tracking) is often used for application development. This code is widely employed at CERN [1, 2, 9, 10] to study interactions in high-energy physics. The simulations and the results obtained are compared with experimental data, to analyze the limitations of physical models. This approach is valuable in hadron therapy. One problem is the computational time needed to implement the Monte Carlo method [17]. A computer with high processing speed and a large memory is required, because depending on the type and complexity of the application, long processing times may be necessary. This feature is available in Brazil through access to the computers at the CESUP (the National Center for Supercomputing at the Federal University of Rio Grande do Sul [UFRGS]). Internationally, several universities allow the use of their mainframe computers. A computer system for dosimetry in radiotherapy is available in Brazil, known as SISCODES, in which depth-dose profiles and isodose curves can be generated and superimposed. This system was developed by Bruno Trindade at the Nuclear Engineering Department, Federal University of Minas Gerais (NRI/UFMG). Simulations of hadron therapy also use data from the Visible Human Project, which may also demand long processing times. Working with simulations requires high-quality hardware.