Periodic Reporting for period 4 - iMPACT (innovative Medical Protons Achromatic Calorimeter and Tracker)
Reporting period: 2020-07-01 to 2021-12-31
• Hadron-therapy is a leading-edge technique which exploits the particular energy deposition prole (Bragg peak) protons or heavy-ions exhibit to target and destroy tumors within the human body. The beneficial aspects of this technique over other, more established, procedures, such as X-ray therapy, have been extensively reported. The effectiveness of a hadron-therapy treatment is strictly related to the accuracy of the knowledge of the tissues density or, equivalently, stopping power (SP) distribution: an accurate 3D map of the body SP makes it possible to precisely determine the position of the Bragg peak as a function of the beam energy. However, the effectiveness of the hadron-therapy procedure is currently limited by the necessity to rely on body density maps produced with X-ray Computed Tomography (X-ray CT), which cannot deliver maps accurate enough to fully exploit the intrinsic accuracy of the technique. This is mainly due to the different behavior inside matter of X-ray and hadrons. A Computed Tomography performed with protons (pCT), instead of X-ray, would therefore improve the accuracy of the SP maps and lead to an enhancement of the treatment effectiveness, as the particles used for both the imaging process and the treatment present the same energy-loss behaviour. Recent studies confirmed that pCT can potentially be a factor 2:5 better, with respect to X-ray CT, in terms of SP values accuracy, with, at the same time, at least a factor 50 lower deposited dose. However the spatial resolution is expected to be worse for pCT than X-ray CT, mostly due to protons multiple Coulomb scattering (MCS).
• The iMPACT Project, innovative Medical Proton Achromatic Calorimeter and Tracker, aims to design and develop a pCT scanner, with the ultimate goal of demonstrating the viability of the pCT technique in a realistic clinical environment. A pCT scanner is composed by a tracker and a calorimeter. The tracker must provide the particles position and angle before and after they pass through the target (the human body), while the calorimeter has to measure the residual energy of the passing particles (Figure 1). By combining the track and energy information of about one billion protons passing through the target from different directions, it is possible reconstruct a 3D image of the target itself.
• The goal of the iMPACT project is therefore to build a proton scanner fast enough to take a full 3D image of the targeted body part (by recording about 1 billion protons passing through it) in few seconds, so that the patient would not move, or even breath, during the irradiation. This would demonstrate the feasibility of a clinically viable pCT system. A successful outcome, in the long term, would mean improving the quality of cancer heavy-ions treatment, as well has creating a 3D body imaging tool less harmfull than current CT scanner, due to the lower dose released to record an image.
• The iMPACT Project, innovative Medical Proton Achromatic Calorimeter and Tracker, aims to design and develop a pCT scanner, with the ultimate goal of demonstrating the viability of the pCT technique in a realistic clinical environment. A pCT scanner is composed by a tracker and a calorimeter. The tracker must provide the particles position and angle before and after they pass through the target (the human body), while the calorimeter has to measure the residual energy of the passing particles (Figure 1). By combining the track and energy information of about one billion protons passing through the target from different directions, it is possible reconstruct a 3D image of the target itself.
• The goal of the iMPACT project is therefore to build a proton scanner fast enough to take a full 3D image of the targeted body part (by recording about 1 billion protons passing through it) in few seconds, so that the patient would not move, or even breath, during the irradiation. This would demonstrate the feasibility of a clinically viable pCT system. A successful outcome, in the long term, would mean improving the quality of cancer heavy-ions treatment, as well has creating a 3D body imaging tool less harmfull than current CT scanner, due to the lower dose released to record an image.
The project completed on track with the development proposed in the SEP-210174671 agreement, and the subsequent amendments, AMD-649031-6, AMD-649031-8 (covid) and AMD-649031-8 (covid). In particular, there were three main deliverables necessary to complete the project: the completion of the calorimeter, the completion of the tracker (equipped with the backup sensors, see previous period report for details), and the design of final sensor for the tracker.
1 )The calorimeter development is completed (Figure 2), as well as the production phase of the final modules. The purchase and assembly of the readout electronics for the full calorimeter has been completed as well (Figure 3), and the calorimeter prototype is now fully operative and under commissioning.
2) The tracker prototype has been equipped with the backup sensors and staves developed in collaboration with CERN (Figure 4), which production has been completed during 2021. Th etracker uses custom-made frames to align the staves with sub-millimetric precision, ensuring complete coverage of the area (Figure 5). The readout electronics developed for the calorimeter has been specifically designed to be compatible with the tracker as well, and in fact has been successfully adapted to readout the tracker.
3) As planned, the design of the final sensor went on, and has been completed within schedule, with the two planned submission completed and delivered (Figure 6). The resulting prototypes have been tested with excellent results. In particular, it was possible to achieve full sensor depletion (Figure 7) and detection efficiency, and the innovative readout architecture did prove effective.
Moreover, the other key tasks necessary to complete the scanner prototype (assembly, system integration, firmware and software development) successfully completed (Figure 8). In particular:
4) The mechanics to mount the tracker, the calorimeter, the target and the support electronics has been designed and produced. The whole scanner assembly is installed on a movable kart to enable an easy moving to testing sites and facilities (Figure 9).
5) The reference target has been acquired, and installed on a rotary stage integrated in the apparatus, to facilitate testing and commissioning (Figure 10).
6) The acquisition firmware and software reached the level necessary to successfully operate the apparatus. While the development work will obviously continue through the next com-missioning and prototyping phase, the current iteration ensures adequate data taking and testing capabilities.
While the covid-19 pandemic limited so far the commissioning on actual beamlines, this will be addressed during 2022, with the goal of completing the apparatus adaptation by early 2023.
1 )The calorimeter development is completed (Figure 2), as well as the production phase of the final modules. The purchase and assembly of the readout electronics for the full calorimeter has been completed as well (Figure 3), and the calorimeter prototype is now fully operative and under commissioning.
2) The tracker prototype has been equipped with the backup sensors and staves developed in collaboration with CERN (Figure 4), which production has been completed during 2021. Th etracker uses custom-made frames to align the staves with sub-millimetric precision, ensuring complete coverage of the area (Figure 5). The readout electronics developed for the calorimeter has been specifically designed to be compatible with the tracker as well, and in fact has been successfully adapted to readout the tracker.
3) As planned, the design of the final sensor went on, and has been completed within schedule, with the two planned submission completed and delivered (Figure 6). The resulting prototypes have been tested with excellent results. In particular, it was possible to achieve full sensor depletion (Figure 7) and detection efficiency, and the innovative readout architecture did prove effective.
Moreover, the other key tasks necessary to complete the scanner prototype (assembly, system integration, firmware and software development) successfully completed (Figure 8). In particular:
4) The mechanics to mount the tracker, the calorimeter, the target and the support electronics has been designed and produced. The whole scanner assembly is installed on a movable kart to enable an easy moving to testing sites and facilities (Figure 9).
5) The reference target has been acquired, and installed on a rotary stage integrated in the apparatus, to facilitate testing and commissioning (Figure 10).
6) The acquisition firmware and software reached the level necessary to successfully operate the apparatus. While the development work will obviously continue through the next com-missioning and prototyping phase, the current iteration ensures adequate data taking and testing capabilities.
While the covid-19 pandemic limited so far the commissioning on actual beamlines, this will be addressed during 2022, with the goal of completing the apparatus adaptation by early 2023.
With the goal of rendering proton Computed tomography (pCT) a viable clinical reality, The iMPACT project advanced the state of the art in two main fields:
1) Successful and development use of Monolithic Advanced Pixels Sensors (MAPS) for medical imaging
The outcome here is twofold: first, a complete tracker has been assembled with current state-of-the-art sensors, the ALPIDE sensor (Figure 11), originally developed for the ALICE High Energy Physics experiment; second, a novel generation of sensors has been produced, with improved performances, specifically designed to meet the requires of medical imaging. Such novel design will also find application in both the space and industrial field, and new research lines have been devised with this specific purpose.
2) Creation of a fast, accurate calorimeter necessary for the pCT
Calorimetry, i.e. the measurement of a particle energy, is a key element toward building a working pCT system. Present state of the art systems use comparatively slow calorimeters, which limits the maximum rate of measurable particles, ultimately resulting in long acquisition times (minutes), incompatible with a real clinical practice. The impact innovative calorimeter reaches a speed which makes it possible to complete an acquisition in 10s or less, making indeed possible to apply the pCT technique in real-worl scenario.
Overall, the project proved the feasibility goals it aimed at. Now that all the hardware has been completed, a long period of commissioning will follow to tune the system, and adapt it to the real necessity of medical imaging outside the lab. Furthermore, the project developed technologies and solution which prompted the interest of the industry, for application bot in the medical field, as well as in the industrial.
1) Successful and development use of Monolithic Advanced Pixels Sensors (MAPS) for medical imaging
The outcome here is twofold: first, a complete tracker has been assembled with current state-of-the-art sensors, the ALPIDE sensor (Figure 11), originally developed for the ALICE High Energy Physics experiment; second, a novel generation of sensors has been produced, with improved performances, specifically designed to meet the requires of medical imaging. Such novel design will also find application in both the space and industrial field, and new research lines have been devised with this specific purpose.
2) Creation of a fast, accurate calorimeter necessary for the pCT
Calorimetry, i.e. the measurement of a particle energy, is a key element toward building a working pCT system. Present state of the art systems use comparatively slow calorimeters, which limits the maximum rate of measurable particles, ultimately resulting in long acquisition times (minutes), incompatible with a real clinical practice. The impact innovative calorimeter reaches a speed which makes it possible to complete an acquisition in 10s or less, making indeed possible to apply the pCT technique in real-worl scenario.
Overall, the project proved the feasibility goals it aimed at. Now that all the hardware has been completed, a long period of commissioning will follow to tune the system, and adapt it to the real necessity of medical imaging outside the lab. Furthermore, the project developed technologies and solution which prompted the interest of the industry, for application bot in the medical field, as well as in the industrial.