Search

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]

Today, there is a steadily growing interest in the use of proton beams for tumor therapy, as they permit to tightly shape the dose delivered to the target reducing the exposure of the surrounding healthy tissues. Nonetheless, accuracy in the determination of the dose distribution in proton-therapy is up to now limited by the uncertainty in stopping powers, which are presently calculated from the photon attenuation coefficients measured by X-ray tomography. Proton computed tomography apparatus (pCT) has been proposed to directly measure the stopping power and reduce this uncertainty. Main problem with proton imaging is the blurring effect introduced by multiple Coulomb scattering: single proton tracking is a promising technique to face this difficulty. As a first step towards a pCT system, we designed a proton radiography (pCR) prototype based on a silicon microstrip tracker (to characterize particle trajectories) and a segmented YAG:Ce calorimeter (to measure their residual energy). Aim of the system is to detect protons with a ∼1 MHz particle rate of and with kinetic energy in the range 250-270 MeV, high enough to pass through human body. Design and development of the pCR prototype, as well as the characterization of its single components, are described in this paper. [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]

As part of a program to investigate the feasibility of proton computed tomography, the most likely path (MLP) of protons inside an absorber was measured in a beam experiment using a silicon strip detector set-up with high position and angular resolution. The locations of 200 MeV protons were measured at three different absorber depth of PolyMethylMethAcrylate-PMMA (3.75, 6.25 and 12.5 cm) and binned in terms of the displacement and the exit angle measured behind the absorber. The observed position distributions were compared to theoretical predictions showing that the location of the protons can be predicted with an accuracy of better than 0.5 mm. [ABSTRACT FROM AUTHOR]