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Monaco V, Ali OH, Bersani D, Abujami M, Boscardin M, Cartiglia N, Betta GFD, Data E, Donetti M, Ferrero M, Ficorella F, Giordanengo S, Villarreal OAM, Milian FM, Mohammadian-Behbahani MR, Olivares DM, Pullia M, Tommasino F, Verroi E, Vignati A, Cirio R, Sacchi R. Performance of LGAD strip detectors for particle counting of therapeutic proton beams. Phys Med Biol 2023; 68:235009. [PMID: 37827167 DOI: 10.1088/1361-6560/ad02d5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Accepted: 10/12/2023] [Indexed: 10/14/2023]
Abstract
Objective. The performance of silicon detectors with moderate internal gain, named low-gain avalanche diodes (LGADs), was studied to investigate their capability to discriminate and count single beam particles at high fluxes, in view of future applications for beam characterization and on-line beam monitoring in proton therapy.Approach. Dedicated LGAD detectors with an active thickness of 55μm and segmented in 2 mm2strips were characterized at two Italian proton-therapy facilities, CNAO in Pavia and the Proton Therapy Center of Trento, with proton beams provided by a synchrotron and a cyclotron, respectively. Signals from single beam particles were discriminated against a threshold and counted. The number of proton pulses for fixed energies and different particle fluxes was compared with the charge collected by a compact ionization chamber, to infer the input particle rates.Main results. The counting inefficiency due to the overlap of nearby signals was less than 1% up to particle rates in one strip of 1 MHz, corresponding to a mean fluence rate on the strip of about 5 × 107p/(cm2·s). Count-loss correction algorithms based on the logic combination of signals from two neighboring strips allow to extend the maximum counting rate by one order of magnitude. The same algorithms give additional information on the fine time structure of the beam.Significance. The direct counting of the number of beam protons with segmented silicon detectors allows to overcome some limitations of gas detectors typically employed for beam characterization and beam monitoring in particle therapy, providing faster response times, higher sensitivity, and independence of the counts from the particle energy.
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Affiliation(s)
- Vincenzo Monaco
- Università degli Studi di Torino, via Pietro Giuria 1, I-10125 Torino, Italy
- Istituto Nazionale di Fisica Nucleare, sezione di Torino, Italy
| | - Omar Hammad Ali
- Fondazione Bruno Kessler, Center for Sensors & Devices , Trento, Italy
| | - Davide Bersani
- Istituto Nazionale di Fisica Nucleare, sezione di Pisa, Italy
| | - Mohammed Abujami
- Università degli Studi di Torino, via Pietro Giuria 1, I-10125 Torino, Italy
- Istituto Nazionale di Fisica Nucleare, sezione di Torino, Italy
| | - Maurizio Boscardin
- Fondazione Bruno Kessler, Center for Sensors & Devices , Trento, Italy
- Trento Institute for Fundamental Physics and Applications, Povo, Trento, Italy
| | | | - Gian Franco Dalla Betta
- Trento Institute for Fundamental Physics and Applications, Povo, Trento, Italy
- Università degli Studi di Trento, Trento, Italy
| | - Emanuele Data
- Università degli Studi di Torino, via Pietro Giuria 1, I-10125 Torino, Italy
- Istituto Nazionale di Fisica Nucleare, sezione di Torino, Italy
| | - Marco Donetti
- CNAO, Centro Nazionale di Adroterapia Oncologica, Pavia, Italy
| | - Marco Ferrero
- Istituto Nazionale di Fisica Nucleare, sezione di Torino, Italy
| | | | | | | | - Felix Mas Milian
- Università degli Studi di Torino, via Pietro Giuria 1, I-10125 Torino, Italy
- Istituto Nazionale di Fisica Nucleare, sezione di Torino, Italy
- Universidade Estadual de Santa Cruz, Department of Exact and Technological Sciences, Ilhéus, Brazil
| | | | - Diango Montalvan Olivares
- Università degli Studi di Torino, via Pietro Giuria 1, I-10125 Torino, Italy
- Istituto Nazionale di Fisica Nucleare, sezione di Torino, Italy
| | - Marco Pullia
- CNAO, Centro Nazionale di Adroterapia Oncologica, Pavia, Italy
| | - Francesco Tommasino
- Trento Institute for Fundamental Physics and Applications, Povo, Trento, Italy
- Università degli Studi di Trento, Trento, Italy
| | - Enrico Verroi
- Trento Institute for Fundamental Physics and Applications, Povo, Trento, Italy
| | - Anna Vignati
- Università degli Studi di Torino, via Pietro Giuria 1, I-10125 Torino, Italy
- Istituto Nazionale di Fisica Nucleare, sezione di Torino, Italy
| | - Roberto Cirio
- Università degli Studi di Torino, via Pietro Giuria 1, I-10125 Torino, Italy
- Istituto Nazionale di Fisica Nucleare, sezione di Torino, Italy
| | - Roberto Sacchi
- Università degli Studi di Torino, via Pietro Giuria 1, I-10125 Torino, Italy
- Istituto Nazionale di Fisica Nucleare, sezione di Torino, Italy
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Krah N, Dauvergne D, Létang JM, Rit S, Testa É. Relative stopping power resolution in time-of-flight proton CT. Phys Med Biol 2022; 67. [DOI: 10.1088/1361-6560/ac7191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 05/19/2022] [Indexed: 11/11/2022]
Abstract
Abstract
Objective. Proton computed tomography (CT) is similar to x-ray CT but relies on protons rather than photons to form an image. In its most common operation mode, the measured quantity is the amount of energy that a proton has lost while traversing the imaged object from which a relative stopping power map can be obtained via tomographic reconstruction. To this end, a calorimeter which measures the energy deposited by protons downstream of the scanned object has been studied or implemented as energy detector in several proton CT prototypes. An alternative method is to measure the proton’s residual velocity and thus its kinetic energy via the time of flight (TOF) between at least two sensor planes. In this work, we study the RSP resolution, seen as image noise, which can be expected from TOF proton CT systems.
Approach. We rely on physics models on the one hand and statistical models of the relevant uncertainties on the other to derive closed form expressions for the noise in projection images. The TOF measurement error scales with the distance between the TOF sensor planes and is reported as velocity error in ps/m. We use variance reconstruction to obtain noise maps of a water cylinder phantom given the scanner characteristics and additionally reconstruct noise maps for a calorimeter-based proton CT system as reference. We use Monte Carlo simulations to verify our model and to estimate the noise due to multiple Coulomb scattering inside the object. We also provide a comparison of TOF helium and proton CT.
Main results. We find that TOF proton CT with 30 ps m−1 velocity error reaches similar image noise as a calorimeter-based proton CT system with 1% energy error (1 sigma error). A TOF proton CT system with a 50 ps m−1 velocity error produces slightly less noise than a 2% calorimeter system. Noise in a reconstructed TOF proton CT image is spatially inhomogeneous with a marked increase towards the object periphery. Our modelled noise was consistent with Monte Carlo simulated images. TOF helium CT offers lower RSP noise at equal fluence, but is less advantageous at equal imaging dose.
Significance. This systematic study of image noise in TOF proton CT can serve as a guide for future developments of this alternative solution for estimating the residual energy of protons and helium ions after the scanned object.
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Ulrich-Pur F, Bergauer T, Burker A, Hirtl A, Irmler C, Kaser S, Pitters F, Rit S. Feasibility study of a proton CT system based on 4D-tracking and residual energy determination via time-of-flight. Phys Med Biol 2022; 67. [PMID: 35354129 DOI: 10.1088/1361-6560/ac628b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 03/30/2022] [Indexed: 11/12/2022]
Abstract
Objective.For dose calculations in ion beam therapy, it is vital to accurately determine the relative stopping power (RSP) distribution within the treatment volume. A suitable imaging modality to achieve the required RSP accuracy is proton computed tomography (pCT), which usually uses a tracking system and a separate residual energy (or range) detector to directly measure the RSP distribution. This work investigates the potential of a novel pCT system based on a single detector technology, namely low gain avalanche detectors (LGADs). LGADs are fast 4D-tracking detectors, which can be used to simultaneously measure the particle position and time with precise timing and spatial resolution. In contrast to standard pCT systems, the residual energy is determined via a time-of-flight (TOF) measurement between different 4D-tracking stations.Approach.To show the potential of using 4D-tracking for proton imaging, we studied and optimized the design parameters for a realistic TOF-pCT system using Monte Carlo simulations. We calculated the RSP accuracy and RSP resolution inside the inserts of the CTP404 phantom and compared the results to a simulation of an ideal pCT system.Main results.After introducing a dedicated calibration procedure for the TOF calorimeter, RSP accuracies less than 0.6% could be achieved. We also identified the design parameters with the strongest impact on the RSP resolution and proposed a strategy to further improve the image quality.Significance.This comprehensive study of the most important design aspects for a novel TOF-pCT system could help guide future hardware developments and, once implemented, improve the quality of treatment planning in ion beam therapy.
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Affiliation(s)
- Felix Ulrich-Pur
- Austrian Academy of Sciences, Institute of High Energy Physics (HEPHY), Nikolsdorfer Gasse 18, A-1050 Wien, Austria
| | - Thomas Bergauer
- Austrian Academy of Sciences, Institute of High Energy Physics (HEPHY), Nikolsdorfer Gasse 18, A-1050 Wien, Austria
| | | | - Albert Hirtl
- TU Wien, Atominstitut, Stadionallee 2, A-1020 Wien, Austria
| | - Christian Irmler
- Austrian Academy of Sciences, Institute of High Energy Physics (HEPHY), Nikolsdorfer Gasse 18, A-1050 Wien, Austria
| | - Stefanie Kaser
- Austrian Academy of Sciences, Institute of High Energy Physics (HEPHY), Nikolsdorfer Gasse 18, A-1050 Wien, Austria
| | - Florian Pitters
- Austrian Academy of Sciences, Institute of High Energy Physics (HEPHY), Nikolsdorfer Gasse 18, A-1050 Wien, Austria
| | - Simon Rit
- Lyon University, INSA-Lyon, University Lyon1, UJM-Saint Etienne, CNRS, Inserm, CREATIS UMR5220, U1206, France
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Pennazio F, Ferrero V, D'Onghia G, Garbolino S, Fiorina E, Marti Villarreal OA, Mas Milian F, Monaco V, Monti V, Patera A, Werner J, Wheadon R, Rafecas M. Proton therapy monitoring: spatiotemporal emission reconstruction with prompt gamma timing and implementation with PET detectors. Phys Med Biol 2022; 67. [PMID: 35193131 DOI: 10.1088/1361-6560/ac5765] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 02/22/2022] [Indexed: 12/17/2022]
Abstract
Objective. In this study we introduce spatiotemporal emission reconstruction prompt gamma timing (SER-PGT), a new method to directly reconstruct the prompt photon emission in the space and time domains inside the patient in proton therapy.Approach. SER-PGT is based on the numerical optimisation of a multidimensional likelihood function, followed by a post-processing of the results. The current approach relies on a specific implementation of the maximum-likelihood expectation maximisation algorithm. The robustness of the method is guaranteed by the complete absence of any information about the target composition in the algorithm.Main results. Accurate Monte Carlo simulations indicate a range resolution of about 0.5 cm (standard deviation) when considering 107primary protons impinging on an homogeneous phantom. Preliminary results on an anthropomorphic phantom are also reported.Significance. By showing the feasibility for the reconstruction of the primary particle range using PET detectors, this study provides significant basis for the development of an hybrid in-beam PET and prompt photon device.
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Affiliation(s)
| | | | | | | | | | | | - Felix Mas Milian
- INFN, Torino, Italy.,Universitá degli Studi di Torino, Torino, Italy.,Universidade Estadual de Santa Cruz, Ilheus, Brazil
| | - Vincenzo Monaco
- INFN, Torino, Italy.,Universitá degli Studi di Torino, Torino, Italy
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