Resumen de Development of Monte Carlo techniques to improve quality control and treatment planning in radiotherapy
The present thesis is aimed at applying the Monte Carlo (MC) methods to solve specific problems related to external radiotherapy practice. It is presented as a compendium of several works described in a series of papers, and the papers are presented in order to show MC applications in all main steps of the treatment chain, both in physical and medical aspects. The main tool used in all the work was the Monte Carlo simulation code PENELOPE for radiation transport with the aid of the penEasy package, a general purpose "main programme" custom made for PENELOPE.
The topics to be addressed were chosen together with fellow scientists and doctors from hospitals because of clinical needs and the expected advantages of MC to solve radiation transport problems in radiotherapy. The main achievements were accomplished both from a simulation point of view, by implementing and using new techniques for speeding up results and reducing uncertainties of calculations, and from a clinical point of view, by improving clinical procedures. A brief summary of the main results obtained is given below.
Phase space files (PSF) of two different accelerator machines (Varian Clinac 2100CD and Varian Clinac 1800) and two cobalt teletherapy units (Eldorado 78 and Theratron-780, Nordion) were calculated and validated by comparison with experimental data.
PENELOPE simulation parameters were optimized by introducing analogue simulation, and various variance reduction techniques were implemented in the penEasy main programme to improve statistical uncertainties and reduce computation time. Moreover parallelization was used. These techniques were applied in the calculation of the response of ionization plane parallel chambers for the Co-60 beam quality and for Metal-Oxide-Field Effect Transistors (MOSFETs) used as radiation dosimeters.
