A new detector for the beam energy measurement in proton therapy: a feasibility study

Vignati, A.; Giordanengo, S.; Milián, Félix Más; Ganjeh, Zahra Ahmadi; Donetti, M.; Fausti, F.; Ferrero, M.; Ali, O. Hammad; Villarreal, Oscar Ariel Martì; Mazza, G.; Shakarami, Z; Sola, V.; Staiano, A.; Cirio, R.; Sacchi, R.; Monaco, V.

doi:10.1088/1361-6560/abab58

Cited by 15 publications

(35 citation statements)

References 37 publications

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“…[4][5][6][7] The proof of concept of a telescope of two Ultra Fast Silicon Detectors (UFSD), able to directly measure the proton beam energy and meeting the clinically required accuracy, corresponding to a maximum error of 1 mm particle range in water, has been recently demonstrated. [8][9][10][11] The proposed detector assesses the mean energy of clinical proton beams by measuring the protons' Time of Flight (ToF), that is, the time needed by single protons to travel a known distance between two sensors. The ToF is a well-known technique that found several applications in the last decades, 11 from nuclear physics 12 to proton radiography, [13][14][15] from the measurement of the kinetic energy of cyclotron and LINAC proton beams up to 30 MeV, 16,17 to the reconstruction of the proton energy spectrum of high-energy laser-driven beams.…”

Section: Introductionmentioning

confidence: 99%

“…[8][9][10][11] The proposed detector assesses the mean energy of clinical proton beams by measuring the protons' Time of Flight (ToF), that is, the time needed by single protons to travel a known distance between two sensors. The ToF is a well-known technique that found several applications in the last decades, 11 from nuclear physics 12 to proton radiography, [13][14][15] from the measurement of the kinetic energy of cyclotron and LINAC proton beams up to 30 MeV, 16,17 to the reconstruction of the proton energy spectrum of high-energy laser-driven beams. 18 The first system prototype proposed by the University and the National Institute for Nuclear Physics (INFN) of Turin, Italy, and its test on clinical beams are described in detail in previous work, 11 and will be rapidly summarized in the following.…”

Section: Introductionmentioning

confidence: 99%

“…The ToF is a well-known technique that found several applications in the last decades, 11 from nuclear physics 12 to proton radiography, [13][14][15] from the measurement of the kinetic energy of cyclotron and LINAC proton beams up to 30 MeV, 16,17 to the reconstruction of the proton energy spectrum of high-energy laser-driven beams. 18 The first system prototype proposed by the University and the National Institute for Nuclear Physics (INFN) of Turin, Italy, and its test on clinical beams are described in detail in previous work, 11 and will be rapidly summarized in the following. The first telescope was made of two 80 μm thick UFSD sensors.…”

Section: Introductionmentioning

confidence: 99%

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Calibration method and performance of a time‐of‐flight detector to measure absolute beam energy in proton therapy

et al. 2023

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BackgroundThe beam energy is one of the most significant parameters in particle therapy since it is directly correlated to the particles’ penetration depth inside the patient. Nowadays, the range accuracy is guaranteed by offline routine quality control checks mainly performed with water phantoms, 2D detectors with PMMA wedges, or multi‐layer ionization chambers. The latter feature low sensitivity, slow collection time, and response dependent on external parameters, which represent limiting factors for the quality controls of beams delivered with fast energy switching modalities, as foreseen in future treatments. In this context, a device based on solid‐state detectors technology, able to perform a direct and absolute beam energy measurement, is proposed as a viable alternative for quality assurance measurements and beam commissioning, paving the way for online range monitoring and treatment verification.PurposeThis work follows the proof of concept of an energy monitoring system for clinical proton beams, based on Ultra Fast Silicon Detectors (featuring tenths of ps time resolution in 50 μm active thickness, and single particle detection capability) and time‐of‐flight techniques. An upgrade of such a system is presented here, together with the description of a dedicated self‐calibration method, proving that this second prototype is able to assess the mean particles energy of a monoenergetic beam without any constraint on the beam temporal structure, neither any a priori knowledge of the beam energy for the calibration of the system.MethodsA new detector geometry, consisting of sensors segmented in strips, has been designed and implemented in order to enhance the statistics of coincident protons, thus improving the accuracy of the measured time differences. The prototype was tested on the cyclotron proton beam of the Trento Protontherapy Center (TPC). In addition, a dedicated self‐calibration method, exploiting the measurement of monoenergetic beams crossing the two telescope sensors for different flight distances, was introduced to remove the systematic uncertainties independently from any external reference.ResultsThe novel calibration strategy was applied to the experimental data collected at TPC (Trento) and CNAO (Pavia). Deviations between measured and reference beam energies in the order of a few hundreds of keV with a maximum uncertainty of 0.5 MeV were found, in compliance with the clinically required water range accuracy of 1 mm.ConclusionsThe presented version of the telescope system, minimally perturbative of the beam, relies on a few seconds of acquisition time to achieve the required clinical accuracy and therefore represents a feasible solution for beam commission, quality assurance checks, and online beam energy monitoring.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Calibration method and performance of a time‐of‐flight detector to measure absolute beam energy in proton therapy

et al. 2023

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“…Keeping the spacing at 10 cm, but reducing the incident beam energy to 180 MeV, which corresponds to a range in water of 21.6 cm, the RSP at the cylinder centre would reduce to 0.9% and to 9% near the edge. Vignati et al (2020) performed first tests in a therapeutic proton beam with a new ultra fast silicon detector based on low gain avalanche diode (LGAD) technology (Pellegrini et al, 2014). They report a time resolution per sensor plane of 75 ps to 115 ps, i.e.…”

Section: Discussionmentioning

confidence: 99%

Relative stopping power precision in time-of-flight proton CT

Krah,

Dauvergne,

Létang

et al. 2021

Preprint

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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 precision, i.e. 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. Main resultsWe find that TOF proton CT with 30 ps/m 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 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.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 after the scanned object.

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“…Fulfilling all these requirements while keeping the production and maintenance costs as well as the system's complexity as low as possible proves to be challenging. A possible solution for a clinically applicable pCT system could be based on 4D-tracking detectors used for both particle path estimation and time-of-flight (TOF) residual energy measurements [14]. Low gain avalanche detectors (LGADs), for example, are promising candidates since they have high rate-capabilities and offer timing resolutions in the order of 30 − 50 ps [15,16] and, depending on the LGAD technology, can have spatial resolutions down to few tens of µm [17,18].…”

Section: Introductionmentioning

confidence: 99%

Feasibility study of a proton CT system based on 4D-tracking and residual energy determination via time-of-flight

Ulrich-Pur,

Bergauer,

Burker

et al. 2021

Preprint

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For dose calculations in ion beam therapy, it is vital to accurately determine the relative stopping power (RSP) distribution within the treated volume. Currently, RSP values are extrapolated from Hounsfield units (HU), measured with x-ray computed tomography (CT), which entails RSP inaccuracies due to conversion errors. A suitable method to improve the treatment plan accuracy is proton computed tomography (pCT). A typical pCT system consists of a tracking system and a separate residual energy (or range) detector to measure the RSP distribution directly. This paper introduces 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 4Dtracking stations. The design parameters for a realistic proton computed tomography system based on 4D-tracking detectors were studied and optimized using Monte Carlo simulations. The RSP accuracy and RSP resolution were measured inside the inserts of the CTP404 phantom to estimate the performance of the pCT system. After introducing a dedicated calibration procedure for the TOF calorimeter, RSP accuracies < 0.6 % could be achieved. Furthermore, the design parameters with the strongest impact on the RSP resolution were identified and a strategy to improve RSP resolution is proposed.

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A new detector for the beam energy measurement in proton therapy: a feasibility study

Cited by 15 publications

References 37 publications

Calibration method and performance of a time‐of‐flight detector to measure absolute beam energy in proton therapy

Calibration method and performance of a time‐of‐flight detector to measure absolute beam energy in proton therapy

Relative stopping power precision in time-of-flight proton CT

Feasibility study of a proton CT system based on 4D-tracking and residual energy determination via time-of-flight

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