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Imaging in Radiation Therapy

Session chair: Mohammadi , Akram (National Institutes for Quantum and Radiological Science and Technology (QST), Chiba, Japan); Parodi , Katia (Ludwig-Maximilians-Universität München (LMU), Department for Medical Physics, Garching, Germany)
Shortcut: M-17
Date: Saturday, 23 October, 2021, 7:00 AM - 8:45 AM
Room: MIC - 1
Session type: MIC Session


Click on an contribution to preview the abstract content.

7:00 AM M-17-01

3D Bragg Peak Imaging with dual-head PEM scanner and Spectral Analysis Approach for Proton Therapy (#79)

M. R. Islam1, 2, M. Miyake1, M. Rahman6, S. Ito3, S. Gotoh4, T. Yamaya5, W. Hiroshi1

1 Tohoku University, Graduate School of Biomedical Engineering, Sendai, Japan
2 Bangladesh Atomic Energy Commission, Institute of Nuclear Medical Physics, Dhaka, Bangladesh
3 Bangladesh Atomic Energy Regularity Authority, Nuclear Safety Security Safeguard Division, Dhaka, Bangladesh
4 Mirai Imaging Inc., Fukushima, Japan
5 Go Proton Japan Inc., Tokyo, Japan
6 National Institute for Quantum and Radiological Science and Technology, Chiba, Japan


The purpose of this study is to visualize a peak near the Bragg peak position that can be used for proton beam verification. Proton therapy is a type of radiation treatment that uses a beam of protons to deliver radiation directly to the tumor and becoming popular due to maximum dose disposition at the Bragg peak. However, proton beam monitoring is the first requisite of the quality treatments of proton therapy. In our study, we proposed a new technique for 3D imaging by dual-head PEMGRAPH that can be used for proton beam verification. The technique extracted the production of 13N in the voxel level by applying Spectral Analysis (SA) approach. Validation studies of this technique were performed. A simulation was constructed with the PHITS Monte Carlo code. Both mono-energetic and spread-out Bragg Peak (SOBP) of 80 MeV proton pencil beam was used for irradiating the water-gel phantom with dimensions of 8 x 10 x 16 cm3. The deposited energy and the positron emitter were recorded as per proton. The simulation data of activated nuclei by proton were converted into activity and made 1 min dynamic frames for 30 min. In experiment, a similar phantom of simulation was prepared and irradiated for 60 sec with 80 MeV mono-energetic pencil proton beam. A prototype dual-head PEMGRAPH was used to acquire 3D time-course data in the list mode for 30 min from the irradiated phantom. The measured data were reconstructed into 1 min dynamic frames using the 3D MLEM algorithm. The SA approach was applied to the time-activity curves (TACs) of 30 min dynamic data and generated SA images for both simulations and experiment. The SA results of PEMGRAPH measurement showed the highest contribution of 13N radionuclide in the Bragg region, concurrent with the simulation results. We conclude that the combination of the PEMGRAPH and SA approach can be a useful tool for proton range verification.


The authors thank to the Cyclotron and Radioisotopes Center (CYRIC) for the technical support.

Keywords: Spectral analysis, proton therapy, positron emitters, Monte Carlo simulation, PEM
7:15 AM M-17-02

Hadron therapy range verification via Machine-Learning aided prompt-gamma imaging (#734)

J. Balibrea-Correa1, J. Lerendegui-Marco1, V. Babiano-Suarez1, C. Domingo-Pardo1, I. Ladarescu1, C. Guerrero2, T. Rodriguez-González2, M. D. C. Jiménez-Ramos3

1 CSIC-University of Valencia, Experimental physics, Valencia, Spain
2 University of Seville, Nuclear physics, Seville, Spain
3 Centro Nacional de Aceleradores, Seville, Spain


The aim of this work is to demonstrate the capability of the i-TED Compton imager for range verification in quasi-real-time prompt gamma-ray (PG) monitoring. PG monitoring constitutes a promising technique for range verification in hadron therapy treatments. Hadron Therapy (HT) with protons introduces advantages with respect to the conventional radiotherapy because of the maximization of the energy deposition (dose) at the Bragg peak. i-TED is an advanced array of Compton cameras originally designed for neutron-capture nuclear experiments. However, due to its large detection efficiency, fast response, high time resolution, compactness, low sensitivity to neutron-induced backgroudns and image resolution, i-TED shows also an excellent performance for medical purposes such as PG monitoring. Furthermore, aiming at improved quality Compton images in the high-energy gamma-ray range characteristic of HT, a novel Machine Learning (ML) methodology has been developed and applied for  identification of full-energy events. To that purpose, a detailed \textsc{Geant4} Monte Carlo (MC) study simulating a clinical irradiation has been performed. We conclude that due to the improvements obtained with ML and the use of GPUs, a system like i-TED can be used for quasi-real time PG monitoring. Finally, we will present first results from an experiment performed at the cyclotron of the CNA facility, Spain, where i-TED was simultaneously operated as in-beam PET and Compton imager.

AcknowledgmentThis work was supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovative programme (ERC Consolidator Grant Project HYMNS, grant agreement 681740). The authors acknowledge partial support from the Spanish MICINN grants and FPA2017-83946-C2-1-P.
Keywords: Nuclear imaging, Machine learning algorithms, Monte Carlo methods
7:30 AM M-17-03

Precise monitoring of the beam movement during scanned carbon-ion beam therapy (#873)

R. Félix Bautista1, 2, L. Ghesquière-Diérickx1, 3, M. Winter4, J. Jakubek5, T. Gehrke1, M. Martišíková1

1 German Cancer Research Center (DKFZ), Department of Medical Physics in Radiation Oncology, Heidelberg, Germany
2 Heidelberg University, Faculty of Physics and Astronomy, Heidelberg, Germany
3 Heidelberg University, Medical Faculty, Heidelberg, Germany
4 Heidelberg Ion-Beam Therapy Center (HIT), Department of Radiation Oncology, Heidelberg, Germany
5 ADVACAM s.r.o., Department of Research and Development, Prague, Czech Republic


A better sparing of healthy tissue and critical organs surrounding a tumor volume is reached in ion beam radiotherapy, in comparison with the conventional X-ray radiotherapy. In radiotherapy with carbon ions, that requires the use of synchrotrons, however, the ion beam delivery is more prone to uncertainties due to the fine-tuning of the beam delivery system, compared to radiotherapy with cyclotron-based protons. These uncertainties can affect the lateral position of the beam during the treatment delivery. This work presents a methodology to monitor the lateral beam positions with high precision by exploiting the tracking of secondary ions produced inside the patient during the treatment delivery. For the secondary ion tracking, a mini-tracker based on Timepix3 detectors was used. The performance of the method was tested in realistic clinic-like treatment situation using an anthropomorphic head phantom irradiated with typical doses at the Heidelberg Ion-Beam Therapy center in Germany. By tracking the secondary ions, the total number of lateral pencil beam positions were successfully measured. Using these data, the beam scanning movement during the delivery was visualized in detail. By comparing to the reference, the majority of the of precision and accuracy values were in line with the clinically accepted uncertainties of ±1 mm.

Keywords: carbon-ion beam radiotherapy, secondary ion tracking, lateral pencil beam positions, Timepix3 detectors
7:45 AM M-17-04

Comparison of two small animal PET prototypes for off-line range verification in carbon beam irradiation (#954)

H. Tashima1, A. Mohammadi1, F. Nishikido1, H. G. Kang1, G. Akamatsu1, S. Takyu1, Y. Iwao1, S. Sato1, H. Ishikawa1, T. Yamaya1

1 National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan


Small animal studies in the carbon ion therapy field are still necessary to understand cancer cell behavior deeply and to explore new medical applications. For precise irradiation with dose monitoring for small animals, PET measurement of positron emitters produced via fragmentation reactions is desired. This study compared our two recently developed small animal PET prototypes with different performance characteristics.  The first is a total body small-animal (TBS) PET prototype with a high sensitivity of 16.7% at the center, while the spatial resolution is limited to about 2 mm. The second is a crosshair light sharing (CLS) PET prototype having sub-millimeter spatial resolution while the sensitivity at the center is limited to 1.0%. Both are compact mobile scanners, which can be moved to an irradiation room at the Heavy-Ion Medical Accelerator in Chiba (HIMAC) for offline PET measurement. Also, they have sufficient axial length for measuring a rat's total body at one time. In this study, cylindrical phantoms of 4 cm diameter and 10 cm length made of polymethyl methacrylate (PMMA) were irradiated with a 290 MeV/u 12C beam (1.2×109 pps) for 16 s. A brass collimator and a PMMA range shifter of 90 mm thickness were placed upstream to adjust the beam shape and the Bragg peak position to the phantom center. Off-line PET measurement start times after the end of irradiation and the measurement times were 5 min and 20 min for TBS PET and 6 min and 30 min for CLS PET, respectively. As a result, peaks in images obtained by TBS and CLS PET prototypes were observed respectively at 4 mm and 3 mm upstream from the Bragg peak position. The obtained image of the CLS PET was significantly noisier than that of TBS PET, although the measurement time of CLS PET was longer. The high sensitivity of the TBS PET prototype is preferred in cases where the number of produced positron emitters is limited.

Keywords: Carbon ion therapy, small animal experiment, range verification, off-line PET
8:00 AM M-17-05

First in-beam imaging test of a high resolution DOI detector system for the SIRMIO PET scanner (#1137)

M. Nitta1, G. Lovatti1, T. Binder1, M. Safari1, H. G. Kang2, C. Gianoli1, G. Dedes1, R. Haghani1, S. Purushothaman3, D. Kostyleva3, D. Boscolo3, E. Heattner3, U. Weber3, C. Schuy3, C. Scheidenberger3, P. Thirolf1, T. Yamaya2, M. Durante3, K. Parodi1

1 Ludwig-Maximilians-Universität München, Medical Physics, Munich, Bavaria, Germany
2 National Institutes for Quantum and Radiological Science and Technology (QST), National Institute of Radiological Sciences (NIRS), Chiba, Japan
3 GSI Helmholtzzentrum für Schwerionenforschung GmbH, BioPhysics, Darmstadt, Hesse, Germany


Small animal proton Irradiator for Research in Molecular Image-guided radiation Oncology” (SIRMIO) is an EU-funded project aiming to realize a prototype system for accurate image-guided small animal proton irradiation at clinical facilities. The design of the SIRMIO PET scanner features a unique spherical shape. The PET detector is composed of a 3-layer pixelated LYSO scintillator with 0.9 mm pixel width and an 8 x 8 SiPM array. In this study we demonstrated the capability of our PET detector system for in-beam PET imaging of radioactive ion beams for the first time, in connection with its planned future application within the “Biomedical Application of Radioactive Beams” (BARB) project at GSI Darmstadt. We used 8 PET detectors; two detector units, each of which consisted of 4 detectors arranged in a cross-shape structure, were placed opposite to each other. The location of a PMMA phantom with a size of 35 cm x 25 cm x 12 cm (long side along the beam) was adjusted such that the Bragg peak position was located at the center of the PET field-of-view. We irradiated C-11 beams with an initial energy of 257 MeV/u. We irradiated the phantom for 40 min and PET data were acquired for 40 min in-beam + additional 20 min off-beam. We used a MLEM for the image reconstruction. The FWHM of a PET peak along the beam direction was 3.1 mm. This work highlights the imaging ability of our high spatial resolution PET detector system for imaging of radioactive ion beams. The results motivate us to pursue further realization of the full-sized SIRMIO PET scanner for the purpose of small animal in-beam PET measurements in proton beam irradiation as well as radioactive ion beam irradiation.

AcknowledgmentThis work is funded by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme through the grant agreements number 725539 (SIRMIO) and 883425 (BARB).  Results are based on an experiment in the context of FAIR Phase-0 at GSI, Darmstadt (Germany).
Keywords: in-beam PET, high resolution PET, radioactive beam, C-11 beam
8:15 AM M-17-06

In vivo verification by means of charged fragments detection in carbon ion therapy treatments at CNAO (#1365)

G. Traini1, G. Baroni8, G. Battistoni4, M. G. Bisogni11, 5, P. Cerello6, M. Ciocca8, M. De Simoni3, 1, M. Donetti8, Y. Dong4, I. Egidi2, A. Embriaco7, V. Ferrero6, E. Fiorina6, 8, M. Fischetti2, 1, G. Franciosini3, 1, A. Kraan5, C. Luongo11, 5, M. Magi2, 1, C. Mancini-Terracciano3, 1, M. Marafini10, 1, E. Malekzadeh8, I. Mattei4, E. Mazzoni11, A. Mirandola8, M. Morrocchi11, 5, S. Muraro4, V. Patera2, 4, F. Pennazio6, A. Schiavi2, 1, A. Sciubba2, 12, E. Solfaroli-Camillocci3, 1, G. Sportelli11, 5, S. Tampellini8, M. Toppi2, 12, A. Trigilio3, 1, B. Vischioni8, V. Vitolo8, A. Sarti2, 1

1 INFN - Sezione di Roma, Rome, Italy
2 Sapienza Università di Roma, Dipartimento di Scienza di Base e Applicate per l'Ingegneria, Rome, Italy
3 Sapienza Università di Roma, Dipartimento di Fisica, Rome, Italy
4 INFN - Sezione di Milano, Milan, Italy
5 INFN - Sezione di Pisa, Pisa, Italy
6 INFN - Sezione di Torino, Torino, Italy
7 INFN - Sezione di Pavia, Pavia, Italy
8 CNAO (Centro Nazionale di Adroterapia Oncologica), Pavia, Italy
9 Centro Studi e Ricerche E Fermi, Roma, Italy
10 Università di Pisa, Dipartimento di Fisica Enrico Fermi, Pisa, Italy
11 INFN - Laboratori Nazionali di Frascati, Frascati, Italy


The application of safety margins in treatment planning to account for possible morphological variations prevents from profiting of the particle therapy intrinsic precision. The development of an in vivo verification system for particle therapy treatments is considered a crucial step forward in improving the clinical outcome, allowing to experimentally check the planned and delivered dose consistency and to re-schedule the treatment when needed. The Dose Profiler is a device designed and built to operate as an in vivo verification system of the carbon ion treatments, exploiting the secondary charged fragments escaping from the patient body. The capability of spotting morphological variations of the Dose Profiler has been investigated for pathologies of the neck-head district in the context of a clinical trial ( Identifier: NCT03662373) carried on at CNAO (Centro Nazionale di Adroterapia Oncologica, Pavia, Italy) from the INSIDE collaboration. To spot possible modifications, the fragments 3D emission map acquired in each fraction has been compared to the one obstained in the first date using the gamma-index computation. The results obtained for three patient are presented in details the potential in detecting the insurgence of morphological changes in clinical condition detecting charged fragments is discussed.

Keywords: Particle Therapy, Range verification
8:30 AM M-17-07

The Effect of CT Dose Reduction on Proton Therapy Dose Calculation and Plan Optimization: A Phantom Study (#628)

M. Elhamiasl1, K. Salvo2, E. Sterpin3, 4, J. Nuyts1

1 KU Leuven, Department of Imaging & Pathology, Leuven, Belgium
2 UZ Leuven, Department of Radiation Oncology, Leuven, Belgium
3 KU Leuven, Department of Oncology, Leuven, Belgium
4 UCLouvain, Institut de Recherche Expérimentale et Clinique, Molecular Imaging Radiotherapy and Oncology Lab, Brussels, Belgium


Protons offer a more precise radiation dose delivery compared to photons, however, they are sensitive to anatomical changes during the course of treatment. Therefore, a CT scan would be paramount at every treatment session to enable accurate dose calculation and subsequent plan adaptation. Nevertheless, the series of CT scans results in the accumulated additional patient dose. We hypothesize that the signal-to-noise ratio provided by conventional CT protocols is higher than needed for proton therapy dose calculations. In this research, we aim to investigate the effect of CT dose reduction on proton therapy dose calculations, plan optimization, and water equivalent thickness calculation. To verify this hypothesis, an in-house CT simulation tool is used to simulate the lower-dose CTs from an existing standard-dose scan. The simulated lower-dose scans are then used for dose calculation, plan optimization, and water equivalent thickness calculation and the results are compared with that of the standard-dose scan. The results on an anthropomorphic head phantom show the possibility of using low-dose CTs for proton therapy dose calculation and plan optimization where a dose reduction by a factor of up to 10 does not have a significant effect on proton dose calculation.

AcknowledgmentThis project is supported by Fonds Baillet-Latour.
Keywords: low-dose CT, proton therapy, dose calculation, plan optimization, CT simulation

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