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Author |
Valdes-Cortez, C.; Ballester, F.; Vijande, J.; Gimenez, V.; Gimenez-Alventosa, V.; Perez-Calatayud, J.; Niatsetski, Y.; Andreo, P. |
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Title  |
Depth-dose measurement corrections for the surface electronic brachytherapy beams of an Esteya(R) unit: a Monte Carlo study |
Type |
Journal Article |
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Year |
2020 |
Publication |
Physics in Medicine and Biology |
Abbreviated Journal |
Phys. Med. Biol. |
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Volume |
65 |
Issue |
24 |
Pages |
245026 - 12pp |
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Keywords |
electronic brachytherapy; eBT; dosimetry; ionization chamber; Monte Carlo |
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Abstract |
Three different correction factors for measurements with the parallel-plate ionization chamber PTW T34013 on the Esteya electronic brachytherapy unit have been investigated. This chamber type is recommended by AAPM TG-253 for depth-dose measurements in the 69.5 kV x-ray beam generated by the Esteya unit. Monte Carlo simulations using the PENELOPE-2018 system were performed to determine the absorbed dose deposited in water and in the chamber sensitive volume at different depths with a Type A uncertainty smaller than 0.1%. Chamber-to-chamber differences have been explored performing measurements using three different chambers. The range of conical applicators available, from 10 to 30 mm in diameter, has been explored. Using a depth-independent global chamber perturbation correction factor without a shift of the effective point of measurement yielded differences between the absorbed dose to water and the corrected absorbed dose in the sensitive volume of the chamber of up to 1% and 0.6% for the 10 mm and 30 mm applicators, respectively. Calculations using a depth-dependent perturbation factor, including or excluding a shift of the effective point of measurement, resulted in depth-dose differences of about +/- 0.5% or less for both applicators. The smallest depth-dose differences were obtained when a shift of the effective point of measurement was implemented, being displaced 0.4 mm towards the center of the sensitive volume of the chamber. The correction factors were obtained with combined uncertainties of 0.4% (k = 2). Uncertainties due to chamber-to-chamber differences are found to be lower than 2%. The results emphasize the relevance of carrying out detailed Monte Carlo studies for each electronic brachytherapy device and ionization chamber used for its dosimetry. |
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Address |
[Valdes-Cortez, Christian; Ballester, Facundo; Vijande, Javier] Univ Valencia UV, Dept Fis Atom Mol & Nucl, Burjassot, Spain, Email: cvalcort@gmail.com |
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Iop Publishing Ltd |
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0031-9155 |
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Notes |
WOS:000618031500001 |
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no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4708 |
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Author |
Brzezinski, K. et al |
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Title |
Detection of range shifts in proton beam therapy using the J-PET scanner: a patient simulation study |
Type |
Journal Article |
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Year |
2023 |
Publication |
Physics in Medicine and Biology |
Abbreviated Journal |
Phys. Med. Biol. |
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Volume |
68 |
Issue |
14 |
Pages |
145016 - 17pp |
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Keywords |
proton therapy; positron emission tomography; in vivo range verification; J-PET; Monte Carlo |
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Abstract |
Objective. The Jagiellonian positron emission tomography (J-PET) technology, based on plastic scintillators, has been proposed as a cost effective tool for detecting range deviations during proton therapy. This study investigates the feasibility of using J-PET for range monitoring by means of a detailed Monte Carlo simulation study of 95 patients who underwent proton therapy at the Cyclotron Centre Bronowice (CCB) in Krakow, Poland. Approach. Discrepancies between prescribed and delivered treatments were artificially introduced in the simulations by means of shifts in patient positioning and in the Hounsfield unit to the relative proton stopping power calibration curve. A dual-layer, cylindrical J-PET geometry was simulated in an in-room monitoring scenario and a triple-layer, dual-head geometry in an in-beam protocol. The distribution of range shifts in reconstructed PET activity was visualized in the beam's eye view. Linear prediction models were constructed from all patients in the cohort, using the mean shift in reconstructed PET activity as a predictor of the mean proton range deviation. Main results. Maps of deviations in the range of reconstructed PET distributions showed agreement with those of deviations in dose range in most patients. The linear prediction model showed a good fit, with coefficient of determination r (2) = 0.84 (in-room) and 0.75 (in-beam). Residual standard error was below 1 mm: 0.33 mm (in-room) and 0.23 mm (in-beam). Significance. The precision of the proposed prediction models shows the sensitivity of the proposed J-PET scanners to shifts in proton range for a wide range of clinical treatment plans. Furthermore, it motivates the use of such models as a tool for predicting proton range deviations and opens up new prospects for investigations into the use of intra-treatment PET images for predicting clinical metrics that aid in the assessment of the quality of delivered treatment. |
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Address |
[Brzezinski, Karol; Gajewski, Jan; Kopec, Renata; Olko, Pawel; Stasica, Paulina; Rucinski, Antoni] Polish Acad Sci, Inst Nucl Phys, Krakow, Poland, Email: karol.brzezinski@ific.uv.es |
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IOP Publishing Ltd |
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0031-9155 |
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Notes |
WOS:001026535700001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5616 |
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Author |
Robert, C.; Dedes, G.; Battistoni, G.; Bohlen, T.T.; Buvat, I.; Cerutti, F.; Chin, M.P.W.; Ferrari, A.; Gueth, P.; Kurz, C.; Lestand, L.; Mairani, A.; Montarou, G.; Nicolini, R.; Ortega, P.G.; Parodi, K.; Prezado, Y.; Sala, P.R.; Sarrut, D.; Testa, E. |
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Title |
Distributions of secondary particles in proton and carbon-ion therapy: a comparison between GATE/Geant4 and FLUKA Monte Carlo codes |
Type |
Journal Article |
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Year |
2013 |
Publication |
Physics in Medicine and Biology |
Abbreviated Journal |
Phys. Med. Biol. |
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Volume |
58 |
Issue |
9 |
Pages |
2879-2899 |
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Abstract |
Monte Carlo simulations play a crucial role for in-vivo treatment monitoring based on PET and prompt gamma imaging in proton and carbon-ion therapies. The accuracy of the nuclear fragmentation models implemented in these codes might affect the quality of the treatment verification. In this paper, we investigate the nuclear models implemented in GATE/Geant4 and FLUKA by comparing the angular and energy distributions of secondary particles exiting a homogeneous target of PMMA. Comparison results were restricted to fragmentation of O-16 and C-12. Despite the very simple target and set-up, substantial discrepancies were observed between the two codes. For instance, the number of high energy (>1 MeV) prompt gammas exiting the target was about twice as large with GATE/Geant4 than with FLUKA both for proton and carbon ion beams. Such differences were not observed for the predicted annihilation photon production yields, for which ratios of 1.09 and 1.20 were obtained between GATE and FLUKA for the proton beam and the carbon ion beam, respectively. For neutrons and protons, discrepancies from 14% (exiting protons-carbon ion beam) to 57% (exiting neutrons-proton beam) have been identified in production yields as well as in the energy spectra for neutrons. |
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Address |
Univ Paris 07, IMNC, CNRS, UMR 8165, F-91406 Orsay, France, Email: robert@imnc.in2p3.fr |
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Iop Publishing Ltd |
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English |
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0031-9155 |
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Notes |
WOS:000317579900010 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1407 |
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Author |
Torres-Espallardo, I.; Diblen, F.; Rohling, H.; Solevi, P.; Gillam, J.; Watts, D.; Espana, S.; Vandenberghe, S.; Fiedler, F.; Rafecas, M. |
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Title |
Evaluation of resistive-plate-chamber-based TOF-PET applied to in-beam particle therapy monitoring |
Type |
Journal Article |
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Year |
2015 |
Publication |
Physics in Medicine and Biology |
Abbreviated Journal |
Phys. Med. Biol. |
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Volume |
60 |
Issue |
9 |
Pages |
N187-N208 |
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Keywords |
PET; in-beam; RPC; particle therapy; TOF; range deviation; partial-ring |
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Abstract |
Particle therapy is a highly conformal radiotherapy technique which reduces the dose deposited to the surrounding normal tissues. In order to fully exploit its advantages, treatment monitoring is necessary to minimize uncertainties related to the dose delivery. Up to now, the only clinically feasible technique for the monitoring of therapeutic irradiation with particle beams is Positron Emission Tomography (PET). In this work we have compared a Resistive Plate Chamber (RPC)-based PET scanner with a scintillation-crystal-based PET scanner for this application. In general, the main advantages of the RPC-PET system are its excellent timing resolution, low cost, and the possibility of building large area systems. We simulated a partial-ring scannerbeam monitoring, which has an intrinsically low positron yield compared to diagnostic PET. In addition, for in-beam PET there is a further data loss due to the partial ring configuration. In order to improve the performance of the RPC-based scanner, an improved version of the RPC detector (modifying the thickness of the gas and glass layers), providing a larger sensitivity, has been simulated and compared with an axially extended version of the crystal-based device. The improved version of the RPC shows better performance than the prototype, but the extended version of the crystal-based PET outperforms all other options. based on an RPC prototype under construction within the Fondazione per Adroterapia Oncologica (TERA). For comparison with the crystal-based PET scanner we have chosen the geometry of a commercially available PET scanner, the Philips Gemini TF. The coincidence time resolution used in the simulations takes into account the current achievable values as well as expected improvements of both technologies. Several scenarios (including patient data) have been simulated to evaluate the performance of different scanners. Initial results have shown that the low sensitivity of the RPC hampers its application to hadron |
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Address |
[Torres-Espallardo, I.; Solevi, P.; Gillam, J.; Rafecas, M.] UV, CSIC, Inst Fis Corpuscular IFIC, E-46071 Valencia, Spain, Email: irene.torres@uv.es |
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Iop Publishing Ltd |
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English |
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0031-9155 |
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Notes |
WOS:000354104700003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2227 |
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Author |
Roser, J.; Muñoz, E.; Barrientos, L.; Barrio, J.; Bernabeu, J.; Borja-Lloret, M.; Etxebeste, A.; Llosa, G.; Ros, A.; Viegas, R.; Oliver, J.F. |
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Title |
Image reconstruction for a multi-layer Compton telescope: an analytical model for three interaction events |
Type |
Journal Article |
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Year |
2020 |
Publication |
Physics in Medicine and Biology |
Abbreviated Journal |
Phys. Med. Biol. |
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Volume |
65 |
Issue |
14 |
Pages |
145005 - 17pp |
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Keywords |
Compton camera; Compton imaging; hadron therapy; image reconstruction; lm-mlem; monte carlo simulations; multi-layer Compton telescope |
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Abstract |
Compton Cameras are electronically collimated photon imagers suitable for sub-MeV to few MeV gamma-ray detection. Such features are desirable to enablein vivorange verification in hadron therapy, through the detection of secondary Prompt Gammas. A major concern with this technique is the poor image quality obtained when the incoming gamma-ray energy is unknown. Compton Cameras with more than two detector planes (multi-layer Compton Cameras) have been proposed as a solution, given that these devices incorporate more signal sequences of interactions to the conventional two interaction events. In particular, three interaction events convey more spectral information as they allow inferring directly the incident gamma-ray energy. A three-layer Compton Telescope based on continuous Lanthanum (III) Bromide crystals coupled to Silicon Photomultipliers is being developed at the IRIS group of IFIC-Valencia. In a previous work we proposed a spectral reconstruction algorithm for two interaction events based on an analytical model for the formation of the signal. To fully exploit the capabilities of our prototype, we present here an extension of the model for three interaction events. Analytical expressions of the sensitivity and the System Matrix are derived and validated against Monte Carlo simulations. Implemented in a List Mode Maximum Likelihood Expectation Maximization algorithm, the proposed model allows us to obtain four-dimensional (energy and position) images by using exclusively three interaction events. We are able to recover the correct spectrum and spatial distribution of gamma-ray sources when ideal data are employed. However, the uncertainties associated to experimental measurements result in a degradation when real data from complex structures are employed. Incorrect estimation of the incident gamma-ray interaction positions, and missing deposited energy associated with escaping secondaries, have been identified as the causes of such degradation by means of a detailed Monte Carlo study. As expected, our current experimental resolution and efficiency to three interaction events prevents us from correctly recovering complex structures of radioactive sources. However, given the better spectral information conveyed by three interaction events, we expect an improvement of the image quality of conventional Compton imaging when including such events. In this regard, future development includes the incorporation of the model assessed in this work to the two interaction events model in order to allow using simultaneously two and three interaction events in the image reconstruction. |
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Address |
[Roser, J.; Munoz, E.; Barrientos, L.; Barrio, J.; Bernabeu, J.; Borja-Lloret, M.; Etxebeste, A.; Llosa, G.; Ros, A.; Viegas, R.; Oliver, J. F.] Inst Fis Corpuscular IFIC CSIC UVEG, Valencia, Spain, Email: Jorge.Roser@ific.uv.es |
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Publisher |
Iop Publishing Ltd |
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English |
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0031-9155 |
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Conference |
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Notes |
WOS:000552701600001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
4481 |
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Author |
Oliver, J.F.; Rafecas, M. |
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Title |
Improving the singles rate method for modeling accidental coincidences in high-resolution PET |
Type |
Journal Article |
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Year |
2010 |
Publication |
Physics in Medicine and Biology |
Abbreviated Journal |
Phys. Med. Biol. |
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Volume |
55 |
Issue |
22 |
Pages |
6951-6971 |
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Keywords |
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Abstract |
Random coincidences ('randoms') are one of the main sources of image degradation in PET imaging. In order to correct for this effect, an accurate method to estimate the contribution of random events is necessary. This aspect becomes especially relevant for high-resolution PET scanners where the highest image quality is sought and accurate quantitative analysis is undertaken. One common approach to estimate randoms is the so-called singles rate method (SR) widely used because of its good statistical properties. SR is based on the measurement of the singles rate in each detector element. However, recent studies suggest that SR systematically overestimates the correct random rate. This overestimation can be particularly marked for low energy thresholds, below 250 keV used in some applications and could entail a significant image degradation. In this work, we investigate the performance of SR as a function of the activity, geometry of the source and energy acceptance window used. We also investigate the performance of an alternative method, which we call 'singles trues' (ST) that improves SR by properly modeling the presence of true coincidences in the sample. Nevertheless, in any real data acquisition the knowledge of which singles are members of a true coincidence is lost. Therefore, we propose an iterative method, STi, that provides an estimation based on ST but which only requires the knowledge of measurable quantities: prompts and singles. Due to inter-crystal scatter, for wide energy windows ST only partially corrects SR overestimations. While SR deviations are in the range 86-300% (depending on the source geometry), the ST deviations are systematically smaller and contained in the range 4-60%. STi fails to reproduce the ST results, although for not too high activities the deviation with respect to ST is only a few percent. For conventional energy windows, i.e. those without inter-crystal scatter, the ST method corrects the SR overestimations, and deviations from the true random rate are of the order of 1% or less. In addition, in the case of conventional energy window STi results reproduce ST results and therefore the former can be used to obtain the true random rate. |
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Address |
[Oliver, Josep F.; Rafecas, Magdalena] Univ Valencia, CSIC, Inst Fis Corpuscular, IFIC, E-46003 Valencia, Spain, Email: josep.f.oliver@uv.es |
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Publisher |
Iop Publishing Ltd |
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English |
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0031-9155 |
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Notes |
ISI:000283789700025 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ elepoucu @ |
Serial |
344 |
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Author |
Borja-Lloret, M.; Barrientos, L.; Bernabeu, J.; Lacasta, C.; Muñoz, E.; Ros, A.; Roser, J.; Viegas, R.; Llosa, G. |
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Title |
Influence of the background in Compton camera images for proton therapy treatment monitoring |
Type |
Journal Article |
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Year |
2023 |
Publication |
Physics in Medicine and Biology |
Abbreviated Journal |
Phys. Med. Biol. |
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Volume |
68 |
Issue |
14 |
Pages |
144001 - 16pp |
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Keywords |
Compton imaging; Compton camera; proton therapy; treatment monitoring; Monte Carlo simulation; image reconstruction; background |
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Abstract |
Objective. Background events are one of the most relevant contributions to image degradation in Compton camera imaging for hadron therapy treatment monitoring. A study of the background and its contribution to image degradation is important to define future strategies to reduce the background in the system. Approach. In this simulation study, the percentage of different kinds of events and their contribution to the reconstructed image in a two-layer Compton camera have been evaluated. To this end, GATE v8.2 simulations of a proton beam impinging on a PMMA phantom have been carried out, for different proton beam energies and at different beam intensities. Main results. For a simulated Compton camera made of Lanthanum (III) Bromide monolithic crystals, coincidences caused by neutrons arriving from the phantom are the most common type of background produced by secondary radiations in the Compton camera, causing between 13% and 33% of the detected coincidences, depending on the beam energy. Results also show that random coincidences are a significant cause of image degradation at high beam intensities, and their influence in the reconstructed images is studied for values of the time coincidence windows from 500 ps to 100 ns. Significance. Results indicate the timing capabilities required to retrieve the fall-off position with good precision. Still, the noise observed in the image when no randoms are considered make us consider further background rejection methods. |
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Address |
[Borja-Lloret, M.; Barrientos, L.; Bernabeu, J.; Lacasta, C.; Munoz, E.; Ros, A.; Roser, J.; Viegas, R.; Llosa, G.] Inst Fis Corpuscular IFIC, CSIC UV, Valencia, Spain, Email: Marina.Borja@csic.es |
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Publisher |
IOP Publishing Ltd |
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English |
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0031-9155 |
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Conference |
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Notes |
WOS:001022671300001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
5571 |
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Author |
Blume, M.; Navab, N.; Rafecas, M. |
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Title |
Joint image and motion reconstruction for PET using a B-spline motion model |
Type |
Journal Article |
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Year |
2012 |
Publication |
Physics in Medicine and Biology |
Abbreviated Journal |
Phys. Med. Biol. |
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Volume |
57 |
Issue |
24 |
Pages |
22pp |
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Keywords |
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Abstract |
We present a novel joint image and motion reconstruction method for PET. The method is based on gated data and reconstructs an image together with amotion function. The motion function can be used to transform the reconstructed image to any of the input gates. All available events (from all gates) are used in the reconstruction. The presented method uses a B-spline motion model, together with a novel motion regularization procedure that does not need a regularization parameter (which is usually extremely difficult to adjust). Several image and motion grid levels are used in order to reduce the reconstruction time. In a simulation study, the presented method is compared to a recently proposed joint reconstruction method. While the presented method provides comparable reconstruction quality, it is much easier to use since no regularization parameter has to be chosen. Furthermore, since the B-spline discretization of the motion function depends on fewer parameters than a displacement field, the presented method is considerably faster and consumes less memory than its counterpart. The method is also applied to clinical data, for which a novel purely data-driven gating approach is presented. |
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Address |
[Blume, Moritz; Rafecas, Magdalena] Univ Valencia, CSIC, Inst Fis Corpuscular IFIC, E-46071 Valencia, Spain, Email: moritz.blume@fasterplan.com |
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Publisher |
Iop Publishing Ltd |
Place of Publication |
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English |
Summary Language |
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0031-9155 |
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Conference |
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Notes |
WOS:000312106200009 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1267 |
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Author |
Roser, J.; Barrientos, L.; Bernabeu, J.; Borja-Lloret, M.; Muñoz, E.; Ros, A.; Viegas, R.; Llosa, G. |
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Title |
Joint image reconstruction algorithm in Compton cameras |
Type |
Journal Article |
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Year |
2022 |
Publication |
Physics in Medicine and Biology |
Abbreviated Journal |
Phys. Med. Biol. |
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Volume |
67 |
Issue |
15 |
Pages |
155009 - 15pp |
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Keywords |
Compton camera; compton imaging; hadron therapy; image reconstruction; LM-MLEM; Monte Carlo simulations; multi-layer compton telescope |
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Abstract |
Objective. To demonstrate the benefits of using an joint image reconstruction algorithm based on the List Mode Maximum Likelihood Expectation Maximization that combines events measured in different channels of information of a Compton camera. Approach. Both simulations and experimental data are employed to show the algorithm performance. Main results. The obtained joint images present improved image quality and yield better estimates of displacements of high-energy gamma-ray emitting sources. The algorithm also provides images that are more stable than any individual channel against the noisy convergence that characterizes Maximum Likelihood based algorithms. Significance. The joint reconstruction algorithm can improve the quality and robustness of Compton camera images. It also has high versatility, as it can be easily adapted to any Compton camera geometry. It is thus expected to represent an important step in the optimization of Compton camera imaging. |
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Address |
[Roser, J.; Barrientos, L.; Bernabeu, J.; Borja-Lloret, M.; Munoz, E.; Ros, A.; Viegas, R.; Llosa, G.] CSIC UV, Inst Fis Corpuscular IFIC, Valencia, Spain, Email: Jorge.Roser@ific.uv.es |
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IOP Publishing Ltd |
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English |
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ISSN |
0031-9155 |
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Notes |
WOS:000827830200001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
5298 |
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Author |
Ros Garcia, A.; Barrio, J.; Etxebeste, A.; Garcia-Lopez, J.; Jimenez-Ramos, M.C.; Lacasta, C.; Muñoz, E.; Oliver, J.F.; Roser, J.; Llosa, G. |
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Title |
MACACO II test-beam with high energy photons |
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Journal Article |
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Year |
2020 |
Publication |
Physics in Medicine and Biology |
Abbreviated Journal |
Phys. Med. Biol. |
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Volume |
65 |
Issue |
24 |
Pages |
245027 - 12pp |
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Keywords |
Compton imaging; Compton camera; proton therapy; LaBr3; test-beam; image reconstruction |
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Abstract |
The IRIS group at IFIC Valencia is developing a three-layer Compton camera for treatment monitoring in proton therapy. The system is composed of three detector planes, each made of a LaBr3<i monolithic crystal coupled to a SiPM array. Having obtained successful results with the first prototype (MACACO) that demonstrated the feasibility of the proposed technology, a second prototype (MACACO II) with improved performance has been developed, and is the subject of this work. The new system has an enhanced detector energy resolution which translates into a higher spatial resolution of the telescope. The image reconstruction method has also been improved with an accurate model of the sensitivity matrix. The device has been tested with high energy photons at the National Accelerator Centre (CNA, Seville). The tests involved a proton beam of 18 MeV impinging on a graphite target, to produce 4.4 MeV photons. Data were taken at different system positions of the telescope with the first detector at 65 and 160 mm from the target, and at different beam intensities. The measurements allowed successful reconstruction of the photon emission distribution at two target positions separated by 5 mm in different telescope configurations. This result was obtained both with data recorded in the first and second telescope planes (two interaction events) and, for the first time in beam experiments, with data recorded in the three planes (three interaction events). |
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Address |
[Ros Garcia, A.; Barrio, J.; Etxebeste, A.; Lacasta, C.; Munoz, E.; Oliver, J. F.; Roser, J.; Llosa, G.] Univ Valencia, CSIC, Inst Fis Corpuscular, Valencia, Spain, Email: arosgar@ific.uv.es |
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Publisher |
Iop Publishing Ltd |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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ISSN |
0031-9155 |
ISBN |
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Notes |
WOS:000600803000001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
4654 |
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| Permanent link to this record |
