Image Reconstruction for Range Verification in Particle Therapy: Institute of Medical Engineering

Algorithms and Modelling for Particle Therapy Verification and Theranostics

In particle therapy, beams of energetic protons or certain ions are used to irradiate tumors or other types of diseased tissue. The interaction of therapeutic particle beams in matter is characterized by a very well-defined range, a high-dose deposition localized in a small region (the Bragg peak), and a steep dose gradient at the distal edge of the Bragg peak. These features imply that possible uncertainties in the determination of the particle range might have severe consequences, such as tumor under-dosage, or the irradiation of healthy tissue. Therefore, safety margins are applied to ensure full treatment of the tumor.

These safety margins could be reduced if the actual dose deposition is quantified with high precision. For this purpose, verification methods aimed to determine the range of the particle beam are under investigation worldwide. Most of these methods are based on the detection of secondary radiation. For example, positron emitting nuclei are created along the beam path; their decay and subsequent annihilation of the emitted positrons give rise to two annihilation photons, which can be detected using similar technology as in Positron Emission Tomography (PET). Another important effect is the excitation of nuclei along the particle path; these nuclei return to their ground state by emitting single gamma rays. Due to the very short half-life of these excited states, these gamma rays are also called prompt gamma radiation.

Our research activities focus on image reconstruction for particle range verification, mainly tomographic Prompt Gamma Imaging (PGI) using Compton cameras, but also in-beam PET. To that end, we employ our in-house implementations of the Maximum-Likelihood Expectation-Maximization (ML-EM) and statistical Origin-Ensemble (OE) algorithms, as well as Bayesian reconstruction approaches. Furthermore, we are investigating novel reconstruction techniques based on Prompt Gamma Timing (PGT) measurements to indirectly determine the particle range and other physical quantities like the stopping power.

Grants

The project is financially supported by the German Research Foundation (DFG) under grant agreements COMMA no. 383681334 and PROSIT no. 516587313.
The project is supported by the North German Supercomputing Alliance (Norddeutscher Verbund für Hoch- und Höchstleistungsrechnen – HLRN), project no.shp00028.
The project was supported by a mobility fellowship within the IFI program of the German Academic Exchange Service (DAAD).

Cooperations

SiFi-CC collaboration
Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Torino, Italy
Instituto de Física Corpuscular (IFIC), CSIC-UV, Valencia

Publications

[ 2024 ]
[ 2023 ]
[ 2022 ]
[ 2021 ]
[ 2020 ]
[ 2019 ]
[ 2018 ]

2024[ to top ]

Werner, J., Ferrero, V., Aglietta, M., Cerello, P., Fiorina, E., Kasprzak, J., Mas Milian, F., Mostardi, F., Pullia, M., Roser, J., Schmid, N., Pennazio, F. and Rafecas, M.: In-beam measurement of stopping power using multi-detector Prompt Gamma Timing in proton therapy, 2024, DOI: 10.1016/j.ejmp.2024.103890.
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@inproceedings{werner2024inbeam, author = {Werner, Julius and Ferrero, Veronica and Aglietta, Marco and Cerello, Piergiorgio and Fiorina, Elisa and Kasprzak, Jona and Mas Milian, Felix and Mostardi, Franco and Pullia, Marco and Roser, Jorge and Schmid, Niklas and Pennazio, Francesco and Rafecas, Magdalena}, booktitle = {Abstracts of the 5th European Congress of Medical Physics}, keywords = {imt}, month = {09}, title = {In-beam measurement of stopping power using multi-detector Prompt Gamma Timing in proton therapy}, volume = 125, year = 2024 }
Werner, J., Schmidt, M., Pennazio, F., Roser, J., Kasprzak, J., Ferrero, V. and Rafecas, M.: An Analytical System Response Model for Spatiotemporal Emission Reconstruction from Multi-Detector Prompt Gamma Timing, 1–1, 2024, DOI: 10.1109/NSS/MIC/RTSD57108.2024.10655960.
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@inproceedings{10655960, abstract = {Particle therapy verification using induced prompt gamma radiation is a field of active research. We employ an iterative reconstruction algorithm to reconstruct the spatiotemporal emission distribution. Due to the fast emission of the prompt gamma radiation after the interaction, their spatiotemporal distribution can be used as a surrogate for the primary particle motion. Using a motion model, we extract the particle range and the stopping power, which should allow direct validation of expected values from treatment planning without additional imaging time. The reconstruction is based on Prompt Gamma Timing spectra from multiple detectors, i.e. the combination of primary particle time of flight before nuclear interaction and secondary photon time of flight until detection outside the patient. Reconstruction requires an accurate model of photon transport and detection, which we previously calculated using extensive Monte-Carlo simulations. Here, we present an analytical model that accelerates calculations by almost 200 times, while matching the Monte-Carlo implementation within 6% of the global maximum value for 99% of all non-zero entries. Furthermore, detection delay caused by secondary particles created by the photons in the detector is studied and its integration into the analytical model demonstrated. First reconstructions of spatiotemporal emission distributions from simulated data using both models show almost perfect agreement. The impact on range and stopping power estimates is currently under investigation.}, author = {Werner, Julius and Schmidt, Malte and Pennazio, Francesco and Roser, Jorge and Kasprzak, Jona and Ferrero, Veronica and Rafecas, Magdalena}, booktitle = {2024 IEEE Nuclear Science Symposium (NSS), Medical Imaging Conference (MIC) and Room Temperature Semiconductor Detector Conference (RTSD)}, keywords = {imt}, month = 10, pages = {1-1}, title = {An Analytical System Response Model for Spatiotemporal Emission Reconstruction from Multi-Detector Prompt Gamma Timing}, year = 2024 }
Roser, J., Kasprzak, J., Llosá, G., Werner, J. and Rafecas, M.: Background reduction of Compton-camera based 3D imaging for range verification in proton therapy, 1–1, 2024, DOI: 10.1109/NSS/MIC/RTSD57108.2024.10655232.
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@inproceedings{10655232, abstract = {Low signal-to-background ratio and subsequent image degradation limits the performance of Compton cameras and hinder their application for range verification in hadron therapy. While several approaches have been explored to improve the signal-to-background ratio via event selection (e.g. with neural networks, energy cuts or using dedicated hardware), background reduction within the 3D image reconstruction process has been hitherto overlooked. In this work we present three such background reduction techniques, and show their potential for image-quality improvement by using simulated data. The explored techniques are shown to reduce image noise-edge artifacts, as well as improve the image contrast and/or be quantitatively closer to the ground truth spatial emission distribution. Such promising results encourage further study on their implementation and impact on range verification.}, author = {Roser, Jorge and Kasprzak, Jona and Llosá, Gabriela and Werner, Julius and Rafecas, Magdalena}, booktitle = {2024 IEEE Nuclear Science Symposium (NSS), Medical Imaging Conference (MIC) and Room Temperature Semiconductor Detector Conference (RTSD)}, keywords = {imt}, month = 10, pages = {1-1}, title = {Background reduction of Compton-camera based 3D imaging for range verification in proton therapy}, year = 2024 }
Werner, J., Pennazio, F., Schmid, N., Fiorina, E., Bersani, D., Cerello, P., Kasprzak, J., Mosco, N., Ranjbar, S., Sacchi, R., Ferrero, V. and Rafecas, M.: Stopping power and range estimations in proton therapy based on prompt gamma timing: motion models and automated parameter optimization, Physics in Medicine & Biology, 2024, DOI: 10.1088/1361-6560/ad5d4b.
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@article{werner2024stopping, author = {Werner, Julius and Pennazio, Francesco and Schmid, Niklas and Fiorina, Elisa and Bersani, Davide and Cerello, Piergiorgio and Kasprzak, Jona and Mosco, Nicola and Ranjbar, Sahar and Sacchi, Roberto and Ferrero, Veronica and Rafecas, Magdalena}, journal = {Physics in Medicine & Biology}, keywords = {imt}, month = {06}, publisher = {IOP Publishing}, title = {Stopping power and range estimations in proton therapy based on prompt gamma timing: motion models and automated parameter optimization}, year = 2024 }
Data, E., Milian, F. M., Abujami, M., Bersani, D., Cerello, P., Donetti, M., Fadavi Mazinani, M., Ferrero, V., Fiorina, E., Garbolino, S., Hosseini, M. A., Montalvan-Olivares, D. M., Pennazio, F., Pullia, M., Ranjbar, S., Werner, J., Wheadon, R. J., Vignati, A., Cirio, R., Sacchi, R. and Giordanengo, S.: A novel detector for 4D tracking in particle therapy, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 169690, 2024, DOI: 10.1016/j.nima.2024.169690.
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@article{data2024novel, author = {Data, Emanuele and Milian, Felix Mas and Abujami, Mohammed and Bersani, Davide and Cerello, Piergiorgio and Donetti, Marco and Fadavi Mazinani, Mohammad and Ferrero, Veronica and Fiorina, Elisa and Garbolino, Sara and Hosseini, Mohammad Amin and Montalvan-Olivares, Diango Manuel and Pennazio, Francesco and Pullia, Marco and Ranjbar, Sahar and Werner, Julius and Wheadon, Richard James and Vignati, Anna and Cirio, Roberto and Sacchi, Roberto and Giordanengo, Simona}, journal = {Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment}, keywords = {imt}, month = {08}, pages = 169690, publisher = {Elsevier BV}, title = {A novel detector for 4D tracking in particle therapy}, year = 2024 }
Ranjbar, S., Data, E., Milian, F. M., Bersani, D., Cerello, P., Cirio, R., Ferrero, V., Mazinani, M. F., Giordanengo, S., Hosseini, M. A., Lombardo, E., Montalvan-Olivares, D. M., Pullia, M., Savazzi, S., Sacchi, R., Vignati, A., Werner, J., Pennazio, F. and Fiorina, E.: First Prompt Gamma Timing measurements with carbon ions, 1–1, 2024, DOI: 10.1109/NSS/MIC/RTSD57108.2024.10655573.
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@inproceedings{10655573, abstract = {The Prompt Gamma Timing (PGT) method provides the assessment of particle range by measuring the time of flight between the primary particle and PG detection. This non-invasive and real-time approach is a tool to monitor the therapy’s effectiveness and reduce uncertainties in treatment planning. We report the first PGT results obtained with carbon ion beams at the sub-clinical rate at the CNAO (Pavia, IT). The experimental setup relies on a silicon strip sensor to measure the transit time of the primaries and a detector based on a monolithic LaBr3-crystal coupled to a Silicon PhotoMultiplier matrix. Homogeneous and in-homogeneous phantoms have been irradiated with carbon ion beams of energy equal to $398 \mathrm{MeV} / \mathrm{u}$. The obtained results are promising, and further tests are foreseen to address clinical rates and prove the applicability of this approach to clinics.}, author = {Ranjbar, Sahar and Data, Emanuele and Milian, Felix Mas and Bersani, Davide and Cerello, Piergiorgio and Cirio, Roberto and Ferrero, Veronica and Mazinani, Mohammad Fadavi and Giordanengo, Simona and Hosseini, Mohammad Amin and Lombardo, Elena and Montalvan-Olivares, Diango Manuel and Pullia, Marco and Savazzi, Simone and Sacchi, Roberto and Vignati, Anna and Werner, Julius and Pennazio, Francesco and Fiorina, Elisa}, booktitle = {2024 IEEE Nuclear Science Symposium (NSS), Medical Imaging Conference (MIC) and Room Temperature Semiconductor Detector Conference (RTSD)}, keywords = {imt}, month = 10, pages = {1-1}, title = {First Prompt Gamma Timing measurements with carbon ions}, year = 2024 }
Fiorina, E., Mas Milian, F., Bersani, D., Cerello, P., Cirio, R., Data, E., Donetti, M., Ferrero, V., Fadavi Mazinani, M., Hosseini, M. A., Lombardo, E., Montalvan-Olivares, D. M., Pennazio, F., Pullia, M., Ranjbar, S., Vignati, A., Werner, J., Sacchi, R. and Giordanengo, S.: Innovative Integrated Beam Monitor and Range Verification System Designed for a Superconducting Multi-Ion Gantry for Particle Therapy, 2024, DOI: 10.1016/j.ejmp.2024.103884.
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@inproceedings{fiorina2024innovative, author = {Fiorina, Elisa and Mas Milian, Felix and Bersani, Davide and Cerello, Piergiorgio and Cirio, Roberto and Data, Emanuele and Donetti, Marco and Ferrero, Veronica and Fadavi Mazinani, Mohammad and Hosseini, Mohammad Amin and Lombardo, Elena and Montalvan-Olivares, Diango Manuel and Pennazio, Francesco and Pullia, Marco and Ranjbar, Sahar and Vignati, Anna and Werner, Julius and Sacchi, Roberto and Giordanengo, Simona}, journal = {Abstracts of the 5th European Congress of Medical Physics}, keywords = {imt}, month = {09}, title = {Innovative Integrated Beam Monitor and Range Verification System Designed for a Superconducting Multi-Ion Gantry for Particle Therapy}, volume = 125, year = 2024 }
Roser, J., Kasprzak, J., Llosá, G., Werner, J. and Rafecas, M.: Background Reduction in Compton-Camera Based 3D Imaging by Using a Non-Uniform Discretization of the Field-of-View, 2024, DOI: 10.1016/j.ejmp.2024.104168.
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@inproceedings{roser2024background, author = {Roser, Jorge and Kasprzak, Jona and Llosá, Gabriela and Werner, Julius and Rafecas, Magdalena}, booktitle = {Abstracts of the 5th European Congress of Medical Physics}, keywords = {imt}, month = {09}, title = {Background Reduction in Compton-Camera Based 3D Imaging by Using a Non-Uniform Discretization of the Field-of-View}, volume = 125, year = 2024 }
Kasprzak, J., Roser, J., Werner, J. and Rafecas, M.: Image Reconstruction with Regularized Origin Ensemble for Proton-Therapy Range Verification with a Compton Camera and Heterogeneous Targets, 2024, DOI: 10.1016/j.ejmp.2024.103920.
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@inproceedings{kasprzak2024image, author = {Kasprzak, Jona and Roser, Jorge and Werner, Julius and Rafecas, Magdalena}, booktitle = {Abstracts of the 5th European Congress of Medical Physics}, keywords = {imt}, month = {09}, title = {Image Reconstruction with Regularized Origin Ensemble for Proton-Therapy Range Verification with a Compton Camera and Heterogeneous Targets}, volume = 125, year = 2024 }

2023[ to top ]

Ferrero, V., Werner, J., Aglietta, M., Cerello, P., Fiorina, E., Mas Milian, F., Mostardi, F., Pennazio, F., Pullia, M., Sacchi, R., Vignati, A. and Rafecas, M.: Proton therapy treatment verification: a spatio-temporal emission reconstruction with experimental data, 2023, DOI: 10.1109/NSSMICRTSD49126.2023.10337908.
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@inproceedings{ferrero2023proton, abstract = {Many efforts have been made to fully exploit charged particles' specific features in terms of dose delivered to the target and sparing of healthy tissues. Although the dose maximum, defined by the Bragg peak, can be well characterized for materials of known composition and physical properties, uncertainties in its determination are encountered in the clinical practice. To mitigate these uncertainties, treatment verification techniques based on the detection of secondaries have gained importance, but a clinical device integrated in the patient routine is yet to be available. We present here the first experimental results of the spatio-temporal emission reconstruction for treatment verification in proton therapy. With a multi-detector prompt-gamma timing system, we are able to simultaneously reconstruct the spatial and temporal distribution of the emitted prompt photons. This distribution is correlated to both the primary particle range and their motion inside the target. A detector prototype comprising two LaBr3:Ce-based detectors and an Ultra Fast Silicon detector was developed within the MERLINO (Measurement of the EneRgy Loss for IN-vivo Optimization in particle therapy) project for the technique proof-of-concept. Experimental measurements of a 227 MeV proton beam impinging on an homogeneous phantom were taken at the National Center for Oncological Hadrontherapy in Italy. First comparisons between data and simulation show excellent agreement, with a 98% average correlation of the prompt gamma timing distributions. A preliminary reconstruction of the prompt photons spatio-temporal emission is here reported for the first time for experimental data. The corresponding simulation was carried out with the FLUKA Monte Carlo tool. The results shown here represent the first step towards the experimental validation of the technique.}, author = {Ferrero, V. and Werner, J. and Aglietta, M. and Cerello, P. and Fiorina, E. and Mas Milian, F. and Mostardi, F. and Pennazio, F. and Pullia, M. and Sacchi, R. and Vignati, A. and Rafecas, M.}, booktitle = {2023 IEEE Nuclear Science Symposium, Medical Imaging Conference and International Symposium on Room-Temperature Semiconductor Detectors (NSS MIC RTSD)}, keywords = {IMT}, month = 11, title = {Proton therapy treatment verification: a spatio-temporal emission reconstruction with experimental data}, year = 2023 }
Kasprzak, J., Werner, J., Schadow, L. and Rafecas, M.: Regularisation of the Origin-Ensemble algorithm with a "Beam Prior" for Particle-Range Verification, 2023, DOI: 10.1109/NSSMICRTSD49126.2023.10337946.
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@inproceedings{kasprzak2023regularisation, abstract = {In particle therapy, potential range uncertainties prevent the full exploitation of ion-beam dose distribution in matter. Tomographic imaging methods such as in-beam PET or Compton-cameras (CC) have been proposed to infer range deviations through the detection of secondary radiation. However, very low counts, data truncation and strong background noise usually distort the reconstructed images. To mitigate these effects when using the Origin Ensemble (OE) reconstruction algorithm, we propose here to regularize OE using a priori information about the beam direction. We derive a prior term from a beam model and test the approach using Monte-Carlo simulations of therapeutic proton beams and a Compton camera. This regularisation term could be adapted to in-beam PET. We have simulated two water-filled phantoms with GATE, the second of which also contained an air cavity to induce a range shift. We reconstructed the images in 3D with various regularisation levels. The beam width required by the prior was first extracted from a reconstruction with few iterations and no regularisation. This gave results comparable to taking the ground-truth beam width. The distal edge shifts were quantified as the differences between the position of the inflection points from a sigmoid fit. First results show that OE with the beam prior can notably enhance image quality and improve the identification of the distal edge position. The outcomes were very sensitive to the regularization parameter. Medium regularization reduced the relative error of the shift from 51.7% without prior to 1.7%, but high regularisation increased the relative error again to 31.7%. Still, regularized OE outperformed conventional OE in most cases. Further studies are planned to characterize the dependencies of the results on the regularization parameter.}, author = {Kasprzak, J. and Werner, J. and Schadow, L. and Rafecas, M.}, booktitle = {2023 IEEE Nuclear Science Symposium, Medical Imaging Conference and International Symposium on Room-Temperature Semiconductor Detectors (NSS MIC RTSD)}, keywords = {IMT}, month = 11, title = {Regularisation of the Origin-Ensemble algorithm with a "Beam Prior" for Particle-Range Verification}, year = 2023 }
Ferrero, V., Aglietta, M., Cerello, P., Fiorina, E., Rafecas, M., Vignati, A., Werner, J. and Pennazio, F.: A new approach to evaluate the stopping power of clinical beams for proton therapy optimization, Physica Medica, 115, 102698, 2023, DOI: 10.1016/j.ejmp.2023.102698.
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@article{ferrero2023approach, author = {Ferrero, V. and Aglietta, M. and Cerello, P. and Fiorina, E. and Rafecas, M. and Vignati, A. and Werner, J. and Pennazio, F.}, journal = {Physica Medica}, keywords = {IMT}, month = 11, pages = 102698, publisher = {Elsevier BV}, title = {A new approach to evaluate the stopping power of clinical beams for proton therapy optimization}, volume = 115, year = 2023 }
Llosá, G. and Rafecas, M.: Hybrid PET/Compton-camera imaging: an imager for the next generation, The European Physical Journal Plus, 138(3), 214, 2023.
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@article{llosa2023hybrid, author = {Llos{\'a}, Gabriela and Rafecas, Magdalena}, journal = {The European Physical Journal Plus}, keywords = {nuci}, number = 3, pages = 214, publisher = {Springer}, title = {Hybrid PET/Compton-camera imaging: an imager for the next generation}, volume = 138, year = 2023 }
Hetzel, R., Urbanevych, V., Bolke, A., Kasper, J., Kercz, M., Kołodziej, M., Magiera, A., Mueller, F., Müller, S., Rafecas, M., Rusiecka, K., Schug, D., Schulz, V., Stahl, A., Weissler, B., Wong, M.-L. and Wrońska, A.: Near-field coded-mask technique and its potential for proton therapy monitoring, Physics in Medicine & Biology, 68(24), 245028, 2023, DOI: 10.1088/1361-6560/ad05b2.
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@article{Hetzel_2023, abstract = {Objective. Prompt-gamma imaging encompasses several approaches to the online monitoring of the beam range or deposited dose distribution in proton therapy. We test one of the imaging techniques - a coded mask approach - both experimentally and via simulations. Approach. Two imaging setups have been investigated experimentally. Each of them comprised a structured tungsten collimator in the form of a modified uniformly redundant array mask and a LYSO:Ce scintillation detector of fine granularity. The setups differed in detector dimensions and operation mode (1D or 2D imaging). A series of measurements with radioactive sources have been conducted, testing the performance of the setups for near-field gamma imaging. Additionally, Monte Carlo simulations of a larger setup of the same type were conducted, investigating its performance with a realistic gamma source distribution occurring during proton therapy. Main results. The images of point-like sources reconstructed from two small-scale prototypes’ data using the maximum-likelihood expectation maximisation algorithm constitute the experimental proof of principle for the near-field coded-mask imaging modality, both in the 1D and the 2D mode. Their precision allowed us to calibrate out certain systematic offsets appearing due to the limited alignment accuracy of setup elements. The simulation of the full-scale setup yielded a mean distal falloff retrieval precision of 0.72 mm in the studies for beam energy range 89.5–107.9 MeV and with 1 × 108 protons (a typical number for distal spots). The implemented algorithm of image reconstruction is relatively fast—a typical procedure needs several seconds. Significance. Coded-mask imaging appears a valid option for proton therapy monitoring. The results of simulations let us conclude that the proposed full-scale setup is competitive with the knife-edge-shaped and the multi-parallel slit cameras investigated by other groups.}, author = {Hetzel, Ronja and Urbanevych, Vitalii and Bolke, Andreas and Kasper, Jonas and Kercz, Monika and Kołodziej, Magdalena and Magiera, Andrzej and Mueller, Florian and Müller, Sara and Rafecas, Magdalena and Rusiecka, Katarzyna and Schug, David and Schulz, Volkmar and Stahl, Achim and Weissler, Bjoern and Wong, Ming-Liang and Wrońska, Aleksandra}, journal = {Physics in Medicine & Biology}, keywords = {nuci}, month = 12, number = 24, pages = 245028, publisher = {IOP Publishing}, title = {Near-field coded-mask technique and its potential for proton therapy monitoring}, volume = 68, year = 2023 }

2022[ to top ]

Ferrero, V., Werner, J., Cerello, P., Fiorina, E., Vignati, A., Pennazio, F. and Rafecas, M.: Estimating the stopping power distribution during proton therapy: A proof of concept, Frontiers in Physics, 2022, DOI: 10.3389/fphy.2022.971767.
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@article{ferrero2022estimating, abstract = {Objective. We introduce a new treatment verification technique to estimate the primary particle's stopping power from prompt gamma timing measurements in proton therapy. Approach. The starting point is the Spatio-temporal Emission Recostruction technique, which provides the time-depth distribution of the emitted prompt photons with a multiple Prompt-Gamma Timing detector setup based on Lanthanum Bromide crystals. A dedicated formalism based on an analytical approximation of the stopping power is developed to obtain the desired information. Its performance is evaluated in a proof of concept configuration via Monte Carlo simulations of monochromatic proton beams impinging on a homogeneous PMMA phantom. Main Results. Results indicate stopping power estimations as good as 3.8% with respect to NIST values, and range estimations within 0.3 cm (standard deviation), when considering 250 ps FWHM timing resolution. Significance. The current study shows, for the first time, the feasibility of evaluating the stopping power of primary beams with a technique that can be performed in-vivo, opening up new possibilities in the field of treatment verification and therapy optimization.}, author = {Ferrero, Veronica and Werner, Julius and Cerello, Piergiorgio and Fiorina, Elisa and Vignati, Anna and Pennazio, Francesco and Rafecas, Magdalena}, editor = {Vasquez Osorio, Eliana Maria}, journal = {Frontiers in Physics}, keywords = {imt}, month = {09}, publisher = {Frontiers}, title = {Estimating the stopping power distribution during proton therapy: A proof of concept}, type = {article}, year = 2022 }
Pennazio, F., Ferrero, V., D’Onghia, G., Garbolino, S., Fiorina, E., Villarreal, O. A. M., Milian, F. M., Monaco, V., Monti, V., Patera, A., Werner, J., Wheadon, R. and Rafecas, M.: Proton therapy monitoring: spatiotemporal emission reconstruction with prompt gamma timing and implementation with PET detectors, Physics in Medicine & Biology, 67(6), 065005, 2022, DOI: 10.1088/1361-6560/ac5765.
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@article{pennazio2022proton, author = {Pennazio, Francesco and Ferrero, Veronica and D'Onghia, Grazia and Garbolino, Sara and Fiorina, Elisa and Villarreal, Oscar Ariel Marti and Milian, Felix Mas and Monaco, Vincenzo and Monti, Valeria and Patera, Alessandra and Werner, Julius and Wheadon, Richard and Rafecas, Magdalena}, journal = {Physics in Medicine & Biology}, keywords = {imt}, month = {03}, number = 6, pages = {065005}, publisher = {{IOP} Publishing}, title = {Proton therapy monitoring: spatiotemporal emission reconstruction with prompt gamma timing and implementation with {PET} detectors}, volume = 67, year = 2022 }
Ferrero, V., Werner, J., Aglietta, M., Cerello, P., Fiorina, E., Gorgi, A., Vignati, A., Rafecas, M. and Pennazio, F.: The MERLINO project:characterization of LaBr3:Ce detectors for stopping power monitoring in proton therapy, Journal of Instrumentation, 17(11), C11013, 2022, DOI: 10.1088/1748-0221/17/11/C11013.
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@article{ferrero2022merlino, abstract = {The MERLINO project is developing a multi-detector setup with the goal of evaluating the beam stopping power from Prompt-Gamma-Timing measurements in proton therapy. The detectors are based on the cerium-doped lanthanum bromide crystal, LaBr3:Ce, coupled to photo-multiplier tubes. The system characterization is ongoing and the first calibration measurements with two detectors showed 124 ps σ and σ E/E = 3% for the timing and energy resolution, respectively. The measured experimental parameters were then used to carry out a preliminary estimation of the stopping power. Results from the simulation of a 189 MeV proton beam impinging on an homogeneous phantom are presented for the optimisation of the MERLINO detector setup.}, author = {Ferrero, V. and Werner, J. and Aglietta, M. and Cerello, P. and Fiorina, E. and Gorgi, A. and Vignati, A. and Rafecas, M. and Pennazio, F.}, journal = {Journal of Instrumentation}, keywords = {imt}, month = 11, number = 11, pages = {C11013}, publisher = {IOP Publishing}, title = {The MERLINO project:characterization of LaBr3:Ce detectors for stopping power monitoring in proton therapy}, volume = 17, year = 2022 }
Werner, J., Ferrero, V., Aglietta, M., Cerello, P., Fiorina, E., Bolke, A., Kasprzak, J., Vignati, A., Pennazio, F. and Rafecas, M.: TOF-ULET: In-beam Stopping Power Estimation using Prompt Gamma Timing towards Adaptive Charged Particle Therapy, 2022, DOI: 10.1109/NSS/MIC44845.2022.10399132.
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@inproceedings{werner2022tofulet, abstract = {The precision of charged particle therapy dose deposition is its main advantage to conventional radiotherapy and its weakness when encountering range uncertainties in clinical practice. We offer a new perspective on treatment verification by introducing a technique to estimate electronic stopping power during the treatment from the measurement of time between particle target entry and prompt gamma detection (TOF-ULET). For the estimation of electronic stopping power, we developed a lightweight analytical model for axial particle motion inside the patient. We used Monte Carlo simulations of a homogenous PMMA phantom as a first test of our method, achieving 6 % estimation errors for 170 MeV and 189 MeV protons. The in-beam estimation of electronic stopping power opens up new opportunities in treatment adaptation between fractions by not only indicating significant deviations from the treatment plan, but also offering a current estimate of the patients’ anatomy along the beam path and – using conversion models – the delivered dose.}, author = {Werner, Julius and Ferrero, Veronica and Aglietta, Marco and Cerello, Piergiorgio and Fiorina, Elisa and Bolke, Andreas and Kasprzak, Jona and Vignati, Anna and Pennazio, Francesco and Rafecas, Magdalena}, booktitle = {2022 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC)}, keywords = {IMT}, month = 11, title = {TOF-ULET: In-beam Stopping Power Estimation using Prompt Gamma Timing towards Adaptive Charged Particle Therapy}, year = 2022 }
Pennazio, F., Werner, J., Aglietta, M., Cerello, P., Fiorina, E., Garbolino, S., Monaco, V., Vignati, A., Wheadon, R., Ferrero, V. and Rafecas, M.: Proton Therapy Treatment Monitoring: Prompt Gamma Emission Reconstruction in the Time and Space Domain, 2022, DOI: 10.1109/NSS/MIC44845.2022.10399204.
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@inproceedings{pennazio2022proton, abstract = {Prompt Gamma Timing is a technique proposed for range monitoring in proton therapy. The experimental measurements so far are limited to a single secondary proton detector. In this study we present an innovative technique to merge the information from many detectors in different positions into a unique estimation of the beam particle motion in the spatiotemporal domain. We test the proposed method by means of Monte Carlo simulations, with various beam ranges and a number of primaries interesting for proton therapy monitoring (107). The method is based on the Maximum Likelihood Expectation Maximization algorithm, and we show its applicability with both MeV-range gamma detectors as well as lower energy detectors such as PET detectors. The preliminary results shown indicate a range resolution of about 5 mm. The ultimate goal of this study is to provide a robust mathematical instrument to expand the significance of Prompt Gamma Timing measurements, to be useful for the prototypes presently under construction by the treatment monitoring community.}, author = {Pennazio, Francesco and Werner, Julius and Aglietta, Marco and Cerello, Piergiorgio and Fiorina, Elisa and Garbolino, Sara and Monaco, Vincenzo and Vignati, Anna and Wheadon, Richard and Ferrero, Veronica and Rafecas, Magdalena}, booktitle = {2022 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC)}, keywords = {IMT}, month = 11, title = {Proton Therapy Treatment Monitoring: Prompt Gamma Emission Reconstruction in the Time and Space Domain}, year = 2022 }

2021[ to top ]

Rusiecka, K., Hetzel, R., Kasper, J., Kozani, M. K., Kohlhase, N., Kolodziej, M., Lalik, R., Magiera, A., Migdal, W., Rafecas, M., Stahl, A., Urbanevych, V., Wong, M. and Wrońska, A.: A systematic study of LYSO:Ce, LuAG:Ce and GAGG:Ce scintillating fibers properties, Journal of Instrumentation, 16(11), P11006, 2021, DOI: 10.1088/1748-0221/16/11/p11006.
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@article{2021, author = {Rusiecka, K. and Hetzel, R. and Kasper, J. and Kozani, M. Kazemi and Kohlhase, N. and Ko{\l}odziej, M. and Lalik, R. and Magiera, A. and Migda{\l}, W. and Rafecas, M. and Stahl, A. and Urbanevych, V. and Wong, M.L. and Wro{\'{n}}ska, A.}, journal = {Journal of Instrumentation}, keywords = {KohlhaseNadja}, month = 11, number = 11, pages = {P11006}, publisher = {{IOP} Publishing}, title = {A systematic study of {LYSO}:Ce, {LuAG}:Ce and {GAGG}:Ce scintillating fibers properties}, volume = 16, year = 2021 }

2020[ to top ]

Kohlhase, N., Stille, M., Bolke, A., Zvolský, M. and Rafecas, M.: Compton Camera Image Reconstruction with A-Priori Information from a Beam Tagging Hodoscope, 1–4, 2020, DOI: 10.1109/NSS/MIC42677.2020.9507820.
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@inproceedings{9507820, abstract = {Compton cameras (CC) have been proposed for range monitoring in proton therapy. The goal is to detected the prompt-gamma (PG) radiation which emerges from the patient, and estimate the underlying activation distribution by using tomographic reconstruction algorithms. The reconstructed CC images are often affected by high levels of statistical noise and other artefacts. With the aim of improving the reconstructed images, here we study various approaches able to exploit a-priori information from a beam-tagging hodoscope. The latter provides an estimation about the beam spread and its direction, so that this information can be used before or during the reconstruction in different ways, e.g. to restrict the volume-of-response assigned to each event, or to design a novel penalty function for regularized image reconstruction. We have implemented several approaches using Monte Carlo simulated data. In particular, our penalized reconstruction led to a significant improvement of the image quality. The estimated distal edge was well resolved for all tested scenarios.}, author = {Kohlhase, Nadja and Stille, Maik and Bolke, Andreas and Zvolský, Milan and Rafecas, Magdalena}, booktitle = {2020 {IEEE} Nuclear Science Symposium and Medical Imaging Conference ({NSS}/{MIC})}, keywords = {StilleMaik}, month = 10, pages = {1-4}, title = {Compton Camera Image Reconstruction with A-Priori Information from a Beam Tagging Hodoscope}, year = 2020 }
Kohlhase, N., Wegener, T., Schaar, M., Bolke, A., Etxebeste, A., Sarrut, D. and Rafecas, M.: Capability of MLEM and OE to Detect Range Shifts with a Compton Camera in Particle Therapy, IEEE Transactions on Radiation and Plasma Medical Sciences, 4(2), 233–242, 2020, DOI: 10.1109/TRPMS.2019.2937675.
- [ BibTeX ]
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@article{8815866, abstract = {To identify range deviations by using Compton cameras (CC), tomographic image reconstruction of CC data is needed. Within this context, image reconstruction is usually performed using Maximum Likelihood Expectation Maximization (MLEM), and more recently, the Origin Ensemble (OE) algorithm. In this work, we investigate how MLEM and OE affect the precision and accuracy of estimated range deviations. In particular, we focus on the effects of data selection, statistical fluctuations, and artifact reduction. The use of external information of the beam path through a hodoscope was also explored. Additionally, two methods to calculate range deviations were tested. To this aim, realistic proton beams were simulated using GATE and data from single spots as well as from 7 contiguous spots of an energy layer were reconstructed. MLEM and OE reacted differently to the poor data statistics. In general, both algorithms were able to detect range shifts for single spots, particularly when multiple coincidences were also considered. Selection of events corresponding to the most relevant energy peaks decreased the identification performance due to the lower statistics. When data from several contiguous spots were jointly reconstructed, the accuracy of the results degraded significantly, and non-zero shifts were assigned when no shifts had occurred. The limited size of the cameras and the subsequent restriction in the orientation and aperture of detected cones, as well as in the number of detected events are major challenges. Future efforts should be devoted to noise regularization and compensation for data truncation.}, author = {{Kohlhase}, N. and {Wegener}, T. and {Schaar}, M. and {Bolke}, A. and {Etxebeste}, A. and {Sarrut}, D. and {Rafecas}, M.}, journal = {IEEE Transactions on Radiation and Plasma Medical Sciences}, keywords = {KohlhaseNadja}, month = {03}, number = 2, pages = {233-242}, title = {Capability of MLEM and OE to Detect Range Shifts with a Compton Camera in Particle Therapy}, volume = 4, year = 2020 }

2019[ to top ]

Kohlhase, N., Wegener, T., Schaar, M., Bolke, A. and Rafecas, M.: Bildrekonstruktion von Compton-Kamera Daten unter Verwendung eines Hodoskops für die Reichweitenverifikation in der Partikeltherapie, 317, 2019.
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@inproceedings{kohlhase2019bildrekonstruktion, author = {Kohlhase, N and Wegener, T and Schaar, M and Bolke, A and Rafecas, M}, booktitle = {50. Jahrestagung der Deutschen Gesellschaft für Medizinische Physik (DGMP) - Abstractband}, editor = {Gromoll, Christian and Wegner, Niels}, keywords = {KohlhaseNadja}, organization = {Deutsche Gesellschaft für Medizinische Physik}, pages = 317, title = {Bildrekonstruktion von Compton-Kamera Daten unter Verwendung eines Hodoskops für die Reichweitenverifikation in der Partikeltherapie}, year = 2019 }
Wegener, T., Kohlhase, N., Schaar, M., Bolke, A. and Rafecas, M.: Stochastic behavior of the Origin-Ensemble Algorithm – effect on ange verification in proton therapy using Compton-Cameras, 240, 2019.
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@inproceedings{wegener2019stochastic, author = {Wegener, T and Kohlhase, N and Schaar, M and Bolke, A and Rafecas, M}, booktitle = {50. Jahrestagung der Deutschen Gesellschaft für Medizinische Physik (DGMP) - Abstractband}, editor = {Gromoll, Christian and Wegner, Niels}, keywords = {KohlhaseNadja}, organization = {Deutsche Gesellschaft für Medizinische Physik}, pages = 240, title = {Stochastic behavior of the Origin-Ensemble Algorithm – effect on ange verification in proton therapy using Compton-Cameras}, year = 2019 }
Ferrero, V., Pennazio, F., Cerello, P., Fiorina, E., Garbolino, S., Monaco, V., Wheadon, R. and Rafecas, M.: Evaluation of in-beam PET treatment verification in proton therapy with different reconstruction methods, IEEE Transactions on Radiation and Plasma Medical Sciences, 2019, DOI: 10.1109/TRPMS.2019.2942713.
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@article{8845670, abstract = {In-beam PET monitoring can provide early treatment assessment in proton therapy. However, open ring configurations and low positron emitter production yields degrade image quality, hampering the assessment accuracy. To achieve the highest precision for range monitoring, it is compulsory to mitigate image noise and compensate for data truncation. The goal of this work is to study the performance of state-of-the-art algorithms for in-beam PET image reconstruction, by evaluating the impact of the system response model and assessing the accuracy of range measurements. The approaches investigated here were Maximum-A-Posteriori algorithms combined with Total-Variation and Median-Root Priors. Maximum-Likelihood-Expectation-Maximization was used as reference. To compute the system matrix, different models were compared: a precise Monte Carlo model, and Single-Ray Tracing with and without Gaussian blurring in image space. The proposed methods were tested on simulations of Spread-Out-Bragg-Peaks delivered on phantoms. The I3PET scanner geometry was used as a case study. After image post-processing, the explored methods delivered similar results. Our work demonstrates the feasibility and reliability of using a simple and fast reconstruction method to perform range evaluations, given the correct image post-processing.}, author = {{Ferrero}, V. and {Pennazio}, F. and {Cerello}, P. and {Fiorina}, E. and {Garbolino}, S. and {Monaco}, V. and {Wheadon}, R. and {Rafecas}, M.}, journal = {IEEE Transactions on Radiation and Plasma Medical Sciences}, keywords = {imt}, title = {Evaluation of in-beam PET treatment verification in proton therapy with different reconstruction methods}, year = 2019 }

2018[ to top ]

Ferrero, V., Cerello, P., Fiorina, E., Monaco, V., Rafecas, M., Wheadon, R. and Pennazio, F.: Innovation in online hadrontherapy monitoring: An in-beam PET and prompt-gamma-timing combined device, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2018, DOI: 10.1016/j.nima.2018.08.065.
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@article{ferrero2018innovation, author = {Ferrero, V. and Cerello, P. and Fiorina, E. and Monaco, V. and Rafecas, M. and Wheadon, R. and Pennazio, F.}, journal = {Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment}, keywords = {imt}, title = {Innovation in online hadrontherapy monitoring: An in-beam PET and prompt-gamma-timing combined device}, year = 2018 }