Avaliação do uso de detectores finos para a produção de imagem com feixes de prótons

Abstract

Since the earliest works proposing the use of protons for imaging, the main advantage of protons over X-rays was expected to be a result of the specific property of the proton flux dropping off very steeply at the end of the particle range. This idea was declared but was not checked. In the present work, this assumption was investigated using the Monte Carlo simulation, with the help of SRIM-2008 software, for the case of a detector that registers only a small part of the proton exit energy (thin detector). First, a thickness of such detector was determined for the investigated water object of 20 cm. Then, it was studied the minimum dose absorbed by an object that is necessary to distinguish two water objects with the thicknesses of 20 cm and 20.1 cm as a function of the initial energy. The results were compared with the case of thick detector that registers the total exit energy. The carried out investigation shows that the principal idea of proton imaging to work near the end of the proton range is not correct in the case of thin detector as well as for thick one. In general, detector systems based on the measurement of the total exit energy are preferable to systems based on thin detectors.