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Status report of the LNS Superconducting Cyclotron

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Rifuggiato D. , Calabretta L. , Cuttone G.

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tom Vol. 48,suppl.2

131-134

EN

The LNS Superconducting Cyclotron has been working in stand alone mode since the beginning of 2000, after 5 years of operation as a booster of the 15 MV Tandem. The new mode has proven to be by far more advantageous than the previous one from the point of view of operation. Working with axial injection, a quite high number of new beam types has been developed. The new mode allows for acceleration of H2 + molecules, which break into two protons when crossing a stripper in the beam line out of the cyclotron. 62 MeV protons have been used for radiotherapy since February 2002. The new mode allows to inject a more intense beam as compared to the previous mode. Therefore, an upgrading program of the cyclotron has started, aiming at having an intense extracted beam to be used as a primary beam in a facility for production of radioactive beams. Beam tests have been accomplished to evaluate transmission figures, while the upgrading of the present electrostatic deflectors has started: new deflector systems, able to dissipate high beam power and allowing for easier maintenance, have been designed and will soon be tested in the machine.

2

Status report of the PSI high power proton cyclotrons

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Humbel M. , Adam S. , Mezger A.

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tom Vol. 48,suppl.2

141-144

EN

In addition to its traditional activities, of improving the availability of its 1 megawatt proton beam, the PSI cyclotron department has started two new projects. One of these is a further increase of the accelerated beam intensity towards 3 mA, the other one is a substantial enhancement of the proton therapy facility.

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Investigation of FLUKA Monte Carlo code to study the influence of degrader and initial proton energy in the Bragg peak position

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Zeghari A. , Bouzekraoui Y. , Bahhous K. , Slassi N. , Cherkaoui El Moursli R.

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2024

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tom Vol. 30, Iss. 4

204--212

EN

Introduction: In recent times, numerous leading global societies have endeavored to advance proton therapy technology with the aim of making it universally accessible. The goal is to offer proton therapy to all cancer patients who stand to benefit from it, thereby enhancing their overall quality of life. This shared objective unites radiation oncologists, medical physicists, radiotherapists, and hospital directors worldwide. The introduction of proton therapy systems, coupled with adjustments to the momentum analysis system, holds potential clinical benefits. Material and Methods: The momentum analysis system typically modifies the energy of the clinical proton beam, influencing the shape and position of the Bragg peak. FLUKA, a Monte Carlo-based software, was employed to simulate various beam setups by directing the proton beam into a water phantom. The resulting Bragg peaks were analyzed and compared with those from different setup simulations. Results: The findings indicate that the Bragg peak undergoes changes in a proton therapy system, both with and without a modulator, across all potential tumor depths. The results demonstrate that the position of the Bragg peak can vary from Z = 31.4 cm for deep tumors such as prostate to Z = 2.6 cm for spinal axis tumors, solely by adjusting the modulator depth from ΔZmodulator = 5 to ΔZmodulator = 30 cm for an energy level of 250 MeV, without altering the proton beam energies. Conclusion: The investigation of these results plays a potential dosimetric consequence, especially for clinics interested in acquiring such a proton therapy system for treating and managing tumors at varying depths.

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First PET Studies of a FLASH Proton Beam: Summary and Future Prospects

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Cesar J. P. , Abouzahr F. , Crespo P. , Gajda M. , Kuo A. , Mawlawi O. , Morozov A. , Ojha A. , Poenisch F. , Proga M. , Sahoo N. , Seco J. , Takaoka T. , Tavienier S. , Titt U. , Wang X. , Zhu X. , Lang K.

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tom Vol. 20, Special issue

49--54

EN

Objectives: Proton therapy, while highly effective and successful, still lacks a key feature: the ability to assess, in-vivo, the dose and end-point location of irradiations. Known as proton range verification, this capability can be realized by incorporating positron emission tomography (PET) systems in both conventional and emerging modalities, such as FLASH proton therapy. FLASH itself may revolutionize radiation oncology with its purported ability to better spare healthy tissues, but only if the underlying mechanisms can be understood. We summarize our work towards establishing in-beam PET modalities and elucidating the mystery of the FLASH effect. Materials: We've developed a PET scanner designed for live, in-beam imaging during therapeutic proton irradiations that can use short-lived positron emitting species (PES) activated by the beam to validate the range and dose of proton depositions. This scanner is made up of PET modules consisting of arrays of LYSO (lutetium-yttrium oxyorthosilicate) scintillating crystals coupled one-to-one to silicon photomultiplier (SiPM) arrays. These modules are readout by electronics based on the TOFPET2 ASIC platform from PETsys Electronics. Methods: Our collaboration with MD Anderson Cancer Center has given us opportunities to take real in-beam data using a non-clinical beamline capable of delivering FLASH proton irradiations into target phantoms made of polymethyl methacrylate (PMMA), high density polyethylene (HDPE), and water. Data collected both during and afterirradiations were used to perform novel analyses and to reconstruct images of PES activity due to the beam. Results: Exploratory studies, using a subset of our PET scanner, have demonstrated successful data acquisition during and after FLASH beam spills including quantitative imaging and dosimetry of activated phantoms. The full results, explored in this work, are highly promising and prove that in-beam PET can deliver on its goals. Upcoming experiments conducted using both FLASH and conventional beams will employ the full PET scanner and involve a rich experimental program with novel ideas for irradiation targets, beam characterization, and in-depth comparisons of the two irradiation modalities. Conclusions: This work demonstrates the unprecedented proof-of-principle for the capabilities of an in-beam PET scanner for imaging and dosimetry of both conventional and FLASH proton beams. These results open a new PET modality with proton beams which is particularly attractive for FLASH therapy but can serve effectively all proton irradiations, leading to improved treatment monitoring and image-guided therapy.

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J-PET application as a Compton camera for proton beam range verification: A preliminary study

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Kozani M. , Rucinski A. , Moskal P.

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tom Vol. 19, no. 1

23--30

EN

Hybrid in-beam PET/Compton camera imaging currently shows a promising approach to use of the quasi-real-time range verification technique in proton therapy. This work aims to assess the capability of utilizing a configuration of the Jagiellonian-positron emission tomography (J-PET) scanner made of plastic scintillator strips, so as to serve as a Compton camera for proton beam range verification. This work reports the production yield results obtained from the GATE/Geant4 simulations, focusing on an energy spectrum (4.2-4.6) MeV of prompt gamma (PG) produced from a clinical proton beam impinging on a water phantom. To investigate the feasibility of J-PET as a Compton camera, a geometrical optimisation was performed. This optimisation was conducted by a point spread function (PSF) study of an isotropic 4.44 MeV gamma source. Realistic statistics of 4.44 MeV PGs obtained from the prior step were employed, simulating interactions with the detector. A sufficient number of detected photons was obtained for the source position reconstruction after performing a geometry optimisation for the proposed J-PET detector. Furthermore, it was demonstrated that more precise calculation of the total deposited energy of coincident events plays a key role in improving the image quality of source distribution determination. A reasonable spatial resolution of 6.5 mm FWHM along the actual proton beam direction was achieved for the first imaging tests. This preliminary study has shown notable potential in using the J-PET application for in-beam PET/Compton camera imaging at quasi-real-time proton range monitoring in future clinical use.

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Image-Guided FLASH Proton Therapy. A dream? Naivety? Arrogance? Or a Necessity?

51%

Lang K.

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tom Vol. 20, Special issue

17--26

EN

Objective: The in-vivo therapy guidance by imaging and dosimetry of proton irradiations, generically known as proton range verification, are some of the most underinvested aspects of radiation oncology. They trail behind other advances in radiation therapy due to the scarcity of sensitive instruments compounded by the lack of treatment protocols for precision monitoring of effects of beam radiation. This is despite that such measurements may dramatically enhance the treatment accuracy and lower the postradiation toxicity, thus improving the entire outcome of cancer therapy. Methods: In this contribution, we focus on the motivation of designing and building of an in-beam time-of-flight (ToF) positron-emission-tomography (PET) scanner with the depth- -of-interaction (DoI) capability for high sensitivity and improved fidelity of imaging. A scanner could be augmented with a tungsten collimator that would enable prompt-gamma imaging (PGI) via single-photon emission computed tomography (SPECT) technique. Results: We present selected results of our pre-clinical experiments with a FLASH proton beam and discuss other related ideas towards improving and expanding the use of PET/PGI/SPECT detectors for proton therapy. A scanner provides an access to data during the spill and past the spill permitting to capture the beam interaction and kinetic monitoring of its effect thus allowing a thorough assessment of each irradiation. Conclusions: A novel scanner for multiple modalities can substantially improve the treatment precision of proton therapy leading to less toxic outcome of irradiations. Using it in the FLASH modality would additionally expand the patient reach of proton therapy.