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We present a set-up for proton computed tomography (pCT), composed of a microstrip silicon tracker and a YAG:Ce calorimeter, able to directly measure the relative stopping power (RSP) maps to be used in hadron therapy. The system, tested with an electron density phantom at the Trento proton Therapy Center, is able to correlate measured and expected RSP with discrepancies of the order of 1% or less. Furthermore, pCT tomographies of an anthropomorphous head phantom taken with our device, when compared with x-ray CT images of the same object, evidence a significant reduction of artifacts induced by titanium spinal bone prosthesis and tungsten dental filling. [ABSTRACT FROM AUTHOR]

Proton therapy is a precise forms of radiation therapy that makes use of high energy proton compared to the conventional, more commonly used and less precise x-ray and electron beams. On the other hand, to fully exploit the proton therapy advantages, very accurate quality controls of the treatments are required. These are mainly related to the dose calculations and treatment planning. Actually dose calculations are routinely performed on the basis of X-Ray computed tomography while a big improvement could be obtained with the direct use of protons as the imaging system. In this work we report the results of Monte Carlo simulations for the study of an imaging system based on the use of high energy protons: the proton Computed. Tomography (pCT). The main limitation of the pCT and the current adopted technical solutions, based on the use of the Most Likely Path (MLP) approximation are illustrated. Simulation results are compared with experimental data obtained with a first prototype of pCT system tested with 200 MeV proton beams available at the Loma Linda University Medical Center (LLUMC) (CA). [ABSTRACT FROM AUTHOR]

Abstract: A first prototype of proton Computed Tomography (pCT) scanner, made of four planes and a calorimeter, has been developed by the PRIMA (PRoton IMAging) Italian collaboration and first results concerning tomographic image reconstruction of experimentally acquired data are discussed in this paper. The Filtered Back-Projection (FBP) algorithm was used to reconstruct projections of a phantom acquired with a 62MeV proton beam. Image noise and spatial resolution were assessed for different parameters of the filter used, with and without selection strategies on proton directions. A satisfactory image quality (0.88mm resolution and 2.5% noise) was achieved even when the backprojection line was defined using only the line connecting the impact points on the second and third planes and all the data were used, irrespective of the proton direction and residual energy. Probably due to the specific detector-phantom arrangement used in this experiment and due to the substantial reduction of the number of useful events, cuts on proton directions did not increase the image resolution significantly. The results confirm the good performances of the PRIMA scanner prototype. They also demonstrate that FBP can produce images of sufficient quality to be used for patient positioning and to initialize iterative pCT reconstruction methods. [Copyright &y& Elsevier]