iMPACT, innovative Medical Proton Achromatic Calorimeter and Tracker, is an ERC funded project hosted by University of Padova and INFN Padova that aims to design, develop and prototype a fast scanner for proton Computed Tomography, a crucial step to improve tumours treatment effectiveness in Hadron Therapy. Computed Tomography represents the first step of the treatment plan, where the 3D Stopping Power map of the patient body is reconstructed and used to calibrate the optimal energy and direction of the beam. Nowadays Computed Tomography is almost exclusively completed using X-Ray beams, even for treatments using protons or ions; in this perspective, using the same particles with the same energy loss features both for the imaging and the treatment leads to a better precision, as the physical interactions are the same. Moreover, in order to obtain comparable density resolutions, with pCT the deposited dose is at considerably lower than with X-rays CT. The main reason why proton Computed Tomography is not yet an applicable technique is the low acquisition rate of the current prototypes that leads to scanning times of the order of tens of minutes. The goal of the iMPACT project is to assemble an extremely fast scanning system, in order to overcome the time. The scanner consists of a silicon pixels tracker and a highly segmented scintillator calorimeter, exploiting leading edge technologies currently used in particle physics. During the development and prototyping phase two relevant issues, that are the focus of this thesis work, have been investigated and assessed. The first issue is to find the best wrapping method for the scintillators, in order to maximise the light collection and minimise the cross-talk between adjacent scintillators, with a low material budget constrain. The second goal is to parametrise the dependence of a single detector's response with respect to the position of the incident particles, in order to verify the response uniformity inside the whole volume of the calorimeter. These studies were conducted with the iLDA (iMPACT Labview Data Acquisition) setup: a ready-to-use desktop system, which exploits cosmic muons as a reliable, easily accessible, repeatable and well known signal source to generate reference datasets. This setup allows to easily carry out tests and characterizations on different candidate detector components for the realization of the iMPACT scanner. This thesis work begins discussing the limitations and advantages of hadron therapy with respect to X-rays therapy, focusing of the interactions of protons with matter. The current state of the art of proton Computed Tomography scanners and different concepts of calorimeters are presented, followed by the description of iMPACT project's scanner. The functioning principle of the SiPM technology used in the project is introduced, as well as the Geant4-based simulation tool specifically developed to study and predict the calorimeter behaviour. The iLDA data acquisition system is then described, followed by a quick overview on cosmic rays and on cosmic muons used for the purpose of this thesis work. The last section of the thesis focuses on the experimental procedure and the obtained results are presented.

Characterization with cosmic muons of plastic scintillators for the iMPACT project calorimeter

Sartore, Sofia
2019/2020

Abstract

iMPACT, innovative Medical Proton Achromatic Calorimeter and Tracker, is an ERC funded project hosted by University of Padova and INFN Padova that aims to design, develop and prototype a fast scanner for proton Computed Tomography, a crucial step to improve tumours treatment effectiveness in Hadron Therapy. Computed Tomography represents the first step of the treatment plan, where the 3D Stopping Power map of the patient body is reconstructed and used to calibrate the optimal energy and direction of the beam. Nowadays Computed Tomography is almost exclusively completed using X-Ray beams, even for treatments using protons or ions; in this perspective, using the same particles with the same energy loss features both for the imaging and the treatment leads to a better precision, as the physical interactions are the same. Moreover, in order to obtain comparable density resolutions, with pCT the deposited dose is at considerably lower than with X-rays CT. The main reason why proton Computed Tomography is not yet an applicable technique is the low acquisition rate of the current prototypes that leads to scanning times of the order of tens of minutes. The goal of the iMPACT project is to assemble an extremely fast scanning system, in order to overcome the time. The scanner consists of a silicon pixels tracker and a highly segmented scintillator calorimeter, exploiting leading edge technologies currently used in particle physics. During the development and prototyping phase two relevant issues, that are the focus of this thesis work, have been investigated and assessed. The first issue is to find the best wrapping method for the scintillators, in order to maximise the light collection and minimise the cross-talk between adjacent scintillators, with a low material budget constrain. The second goal is to parametrise the dependence of a single detector's response with respect to the position of the incident particles, in order to verify the response uniformity inside the whole volume of the calorimeter. These studies were conducted with the iLDA (iMPACT Labview Data Acquisition) setup: a ready-to-use desktop system, which exploits cosmic muons as a reliable, easily accessible, repeatable and well known signal source to generate reference datasets. This setup allows to easily carry out tests and characterizations on different candidate detector components for the realization of the iMPACT scanner. This thesis work begins discussing the limitations and advantages of hadron therapy with respect to X-rays therapy, focusing of the interactions of protons with matter. The current state of the art of proton Computed Tomography scanners and different concepts of calorimeters are presented, followed by the description of iMPACT project's scanner. The functioning principle of the SiPM technology used in the project is introduced, as well as the Geant4-based simulation tool specifically developed to study and predict the calorimeter behaviour. The iLDA data acquisition system is then described, followed by a quick overview on cosmic rays and on cosmic muons used for the purpose of this thesis work. The last section of the thesis focuses on the experimental procedure and the obtained results are presented.
2019-11-24
24
Scintillators, Cosmic Muons, Calorimeter
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.12608/22641