Showing papers by "Pedro Rodrigues published in 2003"
CERN1
TL;DR: The GEANT4 Monte Carlo radiation transport toolkit as discussed by the authors provides the basic services and infrastructure required for the development of flexible simulation frameworks and applications which have found generalized use in high energy physics, nuclear physics, astrophysics and medical physics research.
Abstract: The GEANT4 Monte Carlo radiation transport toolkit provides the basic services and infrastructure required for the development of flexible simulation frameworks and applications which have found generalized use in high energy physics, nuclear physics, astrophysics and medical physics research. GEANT4 object-oriented design provides the possibility to implement or modify any physics process in GEANT4 without changing other parts of the software. This feature makes GEANT4 open to extension of its physics modeling capabilities and to the implementation of alternative physics models. In this paper, the development a simulation platform for performance studies and detector optimization of the Clear-PEM scanner, a high-performance positron emission mammography prototype, and the implementation of precise low energy bremsstrahlung angular generators for the GEANT4 low energy electromagnetic physics category are described.
46 citations
19 Oct 2003
TL;DR: A series of achievements associated with Geant4-based applications in medical physics and, in particular, in radiotherapy, protontherapy, PEM, PET, MRT, metabolic therapy, IORT are presented.
Abstract: We present a series of achievements associated with Geant4-based applications in medical physics and, in particular, in radiotherapy (external beams and brachytherapy), protontherapy, PEM, PET, MRT, metabolic therapy, IORT; projects in microdosimetry and radiobiology are beginning. The Geant4 CT-interface allows to reproduce realistically the patient anatomy, the integration to the GRID allows to run the applications sharing distributed computing resources. The Geant4 Medical Physics Group has born from the collaboration of Geant4 with several research and medical physics institutes in Europe.
39 citations
TL;DR: Applying a simplified model based on the fact that the photons originating Compton electrons (at the first and subsequent collisions) have similar characteristics in air for all the additional collimators, it was shown that these electrons were also responsible for the shift of d(max) in the beam central axis.
Abstract: In radiosurgery narrow photon beams, the depth of maximum dose d max , in the beam central axis increases as the size of the additional collimator increases. This behavior is the opposite of what is observed in radiotherapy conventional beams. To understand this effect, experimental depth dose curves of the additional collimators were obtained for a Siemens KD2 linear accelerator in 6 MV photon mode and the shift of d max varied from 11.0±0.6 mm for the 5 mm collimator to 14.5±0.6 mm for the 23 mm collimator.Monte Carlo simulations showed that the photons that had no interactions in the additional collimators, contributing more than 90% to the total dose in water, were responsible for the shift in d max . Monte Carlo simulations also showed that electrons originated from these photons and contributing to the dosedeposit in water in the beam central axis could be divided in two groups: those that deposit energy far away from their point of origin (the point of the first photon collision in water) and those that deposit energy locally (originated at more than one photon collision in water). Applying a simplified model based on the fact that the photons originating Compton electrons (at the first and subsequent collisions) have similar characteristics in air for all the additional collimators, it was shown that these electrons were also responsible for the shift of d max in the beam central axis. Finally, it was shown that the changes in the initial gradients of the depth dose curves of the additional collimators were mainly due to electrons originated from the first photon collision in water.
15 citations
01 Sep 2003
TL;DR: Geant4 is a powerful and versatile simulation toolkit suitable to a variety of bio-medical applications; opened to extension and evolution.
Abstract: Geant4 is a powerful and versatile simulation toolkit suitable to a variety of bio-medical applications; opened to extension and evolution. The main characteristics of Geant4 are described. Some significant activities in progress both in diagnostic and therapy are presented.
12 citations
01 Jan 2003
TL;DR: The GEANT4 Monte Carlo radiation transport toolkit as discussed by the authors is a tool for high energy physics, nuclear physics, astrophysics and medical physics research, which is developed by the RD44/GEANT4 collaborations.
Abstract: The GEANT4 Monte Carlo radiation transport toolkit, developed by the RD44 and GEANT4 collaborations, aims to become a tool of generalized application in high energy physics, nuclear physics, astrophysics and medical physics research. Due to its Object-Oriented design, GEANT4 is a distinct new approach for the development of flexible simulation applications, while offering a wide energy range coverage both for electromagnetic and hadronic physics processes. GEANT4 provides also an optical physics process category, allowing to describe the production and propagation of scintillation and Cherenkov emitted light. Such capabilities are well tailored for the requirements of the new generation of astrophysics experiments to be installed in the International Space Station, like EUSO and AMS. In this paper, the system architecture of a GEANT4 based simulation framework and its application to EUSO/ULTRA and AMS/RICH performance studies are presented.