Studies for a proton tomography scanner

iMPACT, innovative Medical Proton Achromatic Calorimeter and Tracker, is a University of Padova and INFN project, funded by the European Research Council. The project aim is to design, develop and prototype an extremely fast and accurate proton Computed Tomography Scanner, with the ultimate goal of enabling the realization of a clinically viable proton Computed Tomography (pCT) system. Proton Computed Tomography is an extremely promising technique able to reconstruct density maps (images) of the human body with minimal dose release and high tissue density accuracy, a particularly critical feature in cancer hadron-therapy treatment planning. Hadron-therapy is a leading edge technique where protons or heavy-ions, instead of X-rays, are used to target and destroy the tumor within the human body. By exploiting the peculiar energy deposition distribution such highly ionizing, heavy particles exhibit, it is in fact possible to confine within a volume of few mm3 most of the energy released, hence sparing the healthy tissues surrounding the tumor. However, despite all its beneficial aspects, hadron-therapy is not yet widespread as other more established procedures, such as X-ray therapy. One of the reasons is that the current X-ray Computed Tomography (X-ray CT), currently used to produce body density maps, cannot deliver maps accurate enough to exploit the intrinsic accuracy of the hadron treatment. To precisely aim the hadron energy release with millimeter precision, it is in fact necessary to possess very accurate knowledge of the density it traverse before reaching the tumor. The idea standing behind the development of a pCT scanner is that using the same energy loss behaviour for both the imaging process and the treatment would improve the performance of the latter, the physical interaction process being the same. Currently, several pCT scanner prototypes are being developed around the world; pCT scanner technology however is still far from being applicable in a clinical environment, mainly due to the slow acquisition rates. The iMPACT project therefore plans to develop a pCT scanner able to overcome such limitations, leading the way toward medically sound apparatuses. This thesis work begins by displaying both limitations and advantages of the hadron-therapy technique; the pCT state-of-the-art is then reviewed, highlighting positive features as well as constraints that limit its applicability. The current state of the iMPACT scanner, which embeds a tracker system and a calorimeter, is illustrated and discussed. The thesis then focuses on the development of the calorimeter part of the scanner. The development of a Monte Carlo simulation is presented together with a calibration procedure based on data collected at proton beam tests. Additional studies with proton data are presented with an outlook on future developments.ope

Caratterizzazione pre e post irraggiamento di transistor in tecnologia CMOS 65 nm

E' stata studiata la risposta di transistor PMOS e NMOS, in una tecnologia commerciale CHOS 65 nm, ad effetti di total ionizing dose fino a 1Grad (SiO2)ope

Development of LGAD sensors with a thin entrance window for soft X-ray detection

We show the developments carried out to improve the silicon sensor technology for the detection of soft X-rays with hybrid X-ray detectors. An optimization of the entrance window technology is required to improve the quantum efficiency. The LGAD technology can be used to amplify the signal generated by the X-rays and to increase the signal-to-noise ratio, making single photon resolution in the soft X-ray energy range possible. In this paper, we report first results obtained from an LGAD sensor production with an optimized thin entrance window. Single photon detection of soft X-rays down to 452~eV has been demonstrated from measurements, with a signal-to-noise ratio better than 20.Comment: 10 pages, 6 figure

Characterization of iLGADs using soft X-rays

Experiments at synchrotron radiation sources and X-ray Free-Electron Lasers in the soft X-ray energy range ($250$eV--$2$keV) stand to benefit from the adaptation of the hybrid silicon detector technology for low energy photons. Inverse Low Gain Avalanche Diode (iLGAD) sensors provide an internal gain, enhancing the signal-to-noise ratio and allowing single photon detection below $1$keV using hybrid detectors. In addition, an optimization of the entrance window of these sensors enhances their quantum efficiency (QE). In this work, the QE and the gain of a batch of different iLGAD diodes with optimized entrance windows were characterized using soft X-rays at the Surface/Interface:Microscopy beamline of the Swiss Light Source synchrotron. Above $250$eV, the QE is larger than $55\%$ for all sensor variations, while the charge collection efficiency is close to $100\%$. The average gain depends on the gain layer design of the iLGADs and increases with photon energy. A fitting procedure is introduced to extract the multiplication factor as a function of the absorption depth of X-ray photons inside the sensors. In particular, the multiplication factors for electron- and hole-triggered avalanches are estimated, corresponding to photon absorption beyond or before the gain layer, respectively.Comment: 16 pages, 8 figure

Caratterizzazione pre e post irraggiamento di transistor in tecnologia CMOS 65 nm

E' stata studiata la risposta di transistor PMOS e NMOS, in una tecnologia commerciale CHOS 65 nm, ad effetti di total ionizing dose fino a 1Grad (SiO2

Studies for a proton tomography scanner

iMPACT, innovative Medical Proton Achromatic Calorimeter and Tracker, is a University of Padova and INFN project, funded by the European Research Council. The project aim is to design, develop and prototype an extremely fast and accurate proton Computed Tomography Scanner, with the ultimate goal of enabling the realization of a clinically viable proton Computed Tomography (pCT) system. Proton Computed Tomography is an extremely promising technique able to reconstruct density maps (images) of the human body with minimal dose release and high tissue density accuracy, a particularly critical feature in cancer hadron-therapy treatment planning. Hadron-therapy is a leading edge technique where protons or heavy-ions, instead of X-rays, are used to target and destroy the tumor within the human body. By exploiting the peculiar energy deposition distribution such highly ionizing, heavy particles exhibit, it is in fact possible to confine within a volume of few mm3 most of the energy released, hence sparing the healthy tissues surrounding the tumor. However, despite all its beneficial aspects, hadron-therapy is not yet widespread as other more established procedures, such as X-ray therapy. One of the reasons is that the current X-ray Computed Tomography (X-ray CT), currently used to produce body density maps, cannot deliver maps accurate enough to exploit the intrinsic accuracy of the hadron treatment. To precisely aim the hadron energy release with millimeter precision, it is in fact necessary to possess very accurate knowledge of the density it traverse before reaching the tumor. The idea standing behind the development of a pCT scanner is that using the same energy loss behaviour for both the imaging process and the treatment would improve the performance of the latter, the physical interaction process being the same. Currently, several pCT scanner prototypes are being developed around the world; pCT scanner technology however is still far from being applicable in a clinical environment, mainly due to the slow acquisition rates. The iMPACT project therefore plans to develop a pCT scanner able to overcome such limitations, leading the way toward medically sound apparatuses. This thesis work begins by displaying both limitations and advantages of the hadron-therapy technique; the pCT state-of-the-art is then reviewed, highlighting positive features as well as constraints that limit its applicability. The current state of the iMPACT scanner, which embeds a tracker system and a calorimeter, is illustrated and discussed. The thesis then focuses on the development of the calorimeter part of the scanner. The development of a Monte Carlo simulation is presented together with a calibration procedure based on data collected at proton beam tests. Additional studies with proton data are presented with an outlook on future developments

Development of a Proton Tomography scanner

iMPACT, innovative Medical Proton Achromatic Calorimeter and Tracker, is a University of Padova and INFN research project, funded by the European Research Council. The project aims to design, develop and prototype a fast and accurate proton Computed Tomography (pCT) Scanner, with the ultimate goal of demonstrating the technology necessary to realize a clinically viable pCT system. The overall development, current state, and projected performances of the scanner will be illustrated and discussed. Monte Carlo simulation, a selection of data collected with cosmic rays, and tests with a proton beam will be reviewed as well to quantitatively assess the performance of the apparatus. Preliminary studies on proton track reconstruction, based on a Maximum Likelihood path formalism, will be also presented, together with a supporting object shape identification algorithm. The iMPACT scanner is essentially made by a multi-layer silicon pixels sensors tracker stage using the ALPIDE sensors, and a scintillators-based range calorimeter. There will be an in-depth review of the innovative, highly segmented structure of the calorimeter, based on multiple, orthogonal scintillating elements, and of its read-out architecture, which exploits massive FPGAs parallelism and distributed memory to achieve the triggering and data collection performance necessary to cope with the extremely high event-rate requested by pCT applications. On the tracker side, an overview of the ALPIDE sensor, developed within the ALICE Collaboration for its Inner Tracking System (ITS), and currently adopted for the prototyping phase of the iMPACT tracker, will be illustrated as well, together with the general tracker layout and operations. In parallel, in order improve upon the techniques and methods used in particle physics for tracking purposes, specific studies have been performed to optimize the ALICE ITS alignment, which results will be also presented. Finally, a brief mention will be given to the INFN project ARCADIA, focused on the development of innovative Monolithic Active Pixel Sensors characterized by fully depleted substrate to improve the charge collection efficiency and timing characteristics over a wide range of operational and environmental conditions. The iMPACT project in fact plans to employ the ARCADIA technology to build a pixel detector more suited for the pCT application respect to the ALPIDE sensor.iMPACT, innovative Medical Proton Achromatic Calorimeter and Tracker, is a University of Padova and INFN research project, funded by the European Research Council. The project aims to design, develop and prototype a fast and accurate proton Computed Tomography (pCT) Scanner, with the ultimate goal of demonstrating the technology necessary to realize a clinically viable pCT system. The overall development, current state, and projected performances of the scanner will be illustrated and discussed. Monte Carlo simulation, a selection of data collected with cosmic rays, and tests with a proton beam will be reviewed as well to quantitatively assess the performance of the apparatus. Preliminary studies on proton track reconstruction, based on a Maximum Likelihood path formalism, will be also presented, together with a supporting object shape identification algorithm. The iMPACT scanner is essentially made by a multi-layer silicon pixels sensors tracker stage using the ALPIDE sensors, and a scintillators-based range calorimeter. There will be an in-depth review of the innovative, highly segmented structure of the calorimeter, based on multiple, orthogonal scintillating elements, and of its read-out architecture, which exploits massive FPGAs parallelism and distributed memory to achieve the triggering and data collection performance necessary to cope with the extremely high event-rate requested by pCT applications. On the tracker side, an overview of the ALPIDE sensor, developed within the ALICE Collaboration for its Inner Tracking System (ITS), and currently adopted for the prototyping phase of the iMPACT tracker, will be illustrated as well, together with the general tracker layout and operations. In parallel, in order improve upon the techniques and methods used in particle physics for tracking purposes, specific studies have been performed to optimize the ALICE ITS alignment, which results will be also presented. Finally, a brief mention will be given to the INFN project ARCADIA, focused on the development of innovative Monolithic Active Pixel Sensors characterized by fully depleted substrate to improve the charge collection efficiency and timing characteristics over a wide range of operational and environmental conditions. The iMPACT project in fact plans to employ the ARCADIA technology to build a pixel detector more suited for the pCT application respect to the ALPIDE sensor

Development of a proton computed tomography scanner

iMPACT, innovative Medical Proton Achromatic Calorimeter and Tracker, is a University of Padova and INFN research project, funded by the European Research Council. The project aims to design, develop and prototype a fast and accurate proton Computed Tomography (pCT) Scanner, with the ultimate goal of demonstrating the technology necessary to realize a clinically viable pCT system. The overall development, current state, and projected performances of the scanner will be illustrated and discussed. Monte Carlo simulation, a selection of data collected with cosmic rays, and tests with a proton beam will be reviewed as well to quantitatively assess the performance of the apparatus. Preliminary studies on proton track reconstruction, based on a Maximum Likelihood path formalism, will be also presented, together with a supporting object shape identification algorithm. The iMPACT scanner is essentially made by a multi-layer silicon pixels sensors tracker stage using the ALPIDE sensors, and a scintillators-based range calorimeter. There will be an in-depth review of the innovative, highly segmented structure of the calorimeter, based on multiple, orthogonal scintillating elements, and of its read-out architecture, which exploits massive FPGAs parallelism and distributed memory to achieve the triggering and data collection performance necessary to cope with the extremely high event-rate requested by pCT applications. On the tracker side, an overview of the ALPIDE sensor, developed within the ALICE Collaboration for its Inner Tracking System (ITS), and currently adopted for the prototyping phase of the iMPACT tracker, will be illustrated as well, together with the general tracker layout and operations. In parallel, in order improve upon the techniques and methods used in particle physics for tracking purposes, specific studies have been performed to optimize the ALICE ITS alignment, which results will be also presented. Finally, a brief mention will be given to the INFN project ARCADIA, focused on the development of innovative Monolithic Active Pixel Sensors characterized by fully depleted substrate to improve the charge collection efficiency and timing characteristics over a wide range of operational and environmental conditions. The iMPACT project in fact plans to employ the ARCADIA technology to build a pixel detector more suited for the pCT application compared to the ALPIDE sensor

High-resolution-cone beam tomography analysis of bone microarchitecture in patients with acromegaly and radiological vertebral fractures

Vertebral fractures are an emerging complication of acromegaly but their prediction is still difficult occurring even in patients with normal bone mineral density. In this study we evaluated the ability of high-resolution cone-beam computed tomography to provide information on skeletal abnormalities associated with vertebral fractures in acromegaly. 40 patients (24 females, 16 males; median age 57 years, range 25-72) and 21 healthy volunteers (10 females, 11 males; median age 60 years, range: 25-68) were evaluated for trabecular (bone volume/trabecular volume ratio, mean trabecular separation, and mean trabecular thickness) and cortical (thickness and porosity) parameters at distal radius using a high-resolution cone-beam computed tomography system. All acromegaly patients were evaluated for morphometric vertebral fractures and for mineral bone density by dual-energy X-ray absorptiometry at lumbar spine, total hip, femoral neck, and distal radius. Acromegaly patients with vertebral fractures (15 cases) had significantly (p < 0.05) lower bone volume/trabecular volume ratio, greater mean trabecular separation, and higher cortical porosity vs. nonfractured patients, without statistically significant differences in mean trabecular thickness and cortical thickness. Fractured and nonfractured acromegaly patients did not have significant differences in bone density at either skeletal site. Patients with acromegaly showed lower bone volume/trabecular volume ratio (p = 0.003) and mean trabecular thickness (p < 0.001) and greater mean trabecular separation (p = 0.02) as compared to control subjects, without significant differences in cortical thickness and porosity. This study shows for the first time that abnormalities of bone microstructure are associated with radiological vertebral fractures in acromegaly. High-resolution cone-beam computed tomography at the distal radius may be useful to evaluate and predict the effects of acromegaly on bone microstructure

iMPACT: An Innovative Tracker and Calorimeter for Proton Computed Tomography

This contribution describes the first results obtained within the iMPACT project, which aims to build a novel proton computed-tomography (pCT) scanner for protons of energy up to 230 MeV, as used in hadron therapy. The iMPACT pCT scanner will improve the current state-of-the-art in proton tracking at all levels: speed, spatial resolution, material budget, and cost. We will first describe the design of the iMPACT scanner, which is composed by a tracker and a range calorimeter. We will then illustrate the results of a test with the ALPIDE sensor, a monolithic active pixels sensor, developed by the ALICE collaboration, which will equip the iMPACT tracker in this first phase. We finally detail the characterization building elements of the prototype of the range calorimeter, which is composed of segmented scintillator fingers readout by SiPMs. Reported beam-test data will highlight how the technological choices we made well address the performances of a state-of-the-art pCT system