Beam optics study for energy selection system of SC200 superconducting proton cyclotron

Zeng, Xianhu; Zheng, Jinxing; Song, Yuntao; Jiang, Feng; Li, Ming; Zhang, Wu-Quan; Zhu, Lei

doi:10.1007/s41365-018-0462-5

Cited by 10 publications

(4 citation statements)

References 8 publications

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“…This introduces additional considerations to the transport and design of the beamline and also results in several differences to the beam quality and properties. Extensive details can be found in literature [5,8,9,10,11] however for the context of ocular treatments, we mention some key physical characteristics. Facilities which operate at close to the maximum machine energy are able to generate a fixed, passively scattered beam with minimal energy or range straggling effects.…”

Section: Facility and Treatment Considerationsmentioning

confidence: 99%

Beam characterisation studies of the 62 MeV proton therapy beamline at the Clatterbridge Cancer Centre

et al. 2020

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Section: Facility and Treatment Considerationsmentioning

confidence: 99%

Beam characterisation studies of the 62 MeV proton therapy beamline at the Clatterbridge Cancer Centre

et al. 2020

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“…Therefore, to minimize beam losses in the beamline, it is necessary to use beam emittance selection collimators after the degrader and momentum selection slits in the energy selection system (ESS) to restrict the emittance and momen-tum spread to the requirement of the following beamline or gantry. 20,22 Currently, all cyclotron-based proton therapy facilities transport a maximum emittance of 30 π*mm*mrad through the beamline [22][23][24][25][26][27] (in this work, beam sizes, divergences, and emittances are expressed as 2σ values), which limits the transmission of lowenergy beams.For example,for the lower energies transported by the Gantry 2 at our institute (70-100 MeV), transmission from the cyclotron to the isocenter is of the order of only 0.1%, limiting beam intensity and therefore increasing treatment times, particularly for superficial tumors.…”

Section: Introductionmentioning

confidence: 99%

A new emittance selection system to maximize beam transmission for low‐energy beams in cyclotron‐based proton therapy facilities with gantry

et al. 2021

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In proton therapy, the potential of using high-dose rates in the cancer treatment is being explored. High-dose rates could improve efficiency and throughput in standard clinical practice, allow efficient utilization of motion mitigation techniques for moving targets, and potentially enhance normal tissue sparing due to the so-called FLASH effect. However, high-dose rates are difficult to reach when lower energy beams are applied in cyclotron-based proton therapy facilities, because they result in large beam sizes and divergences downstream of the degrader, incurring large losses from the cyclotron to the patient position (isocenter). In current facilities, the emittance after the degrader is reduced using circular collimators; however, this does not provide an optimal matching to the acceptance of the following beamline, causing a low transmission for these energies. We, therefore, propose to use a collimation system, asymmetric in both beam size and divergence, resulting in symmetric emittance in both beam transverse planes as required for a gantry system. This new emittance selection, together with a new optics design for the following beamline and gantry, allows a better matching to the beamline acceptance and an improvement of the transmission. Methods: We implemented a custom method to design the collimator sizes and shape required to select high emittance, to be transported by the following beamline using new beam optics (designed with TRANSPORT) to maximize acceptance matching. For predicting the transmission in the new configuration (new collimators + optics), we used Monte Carlo simulations implemented in BDSIM, implementing a model of PSI Gantry 2 which we benchmarked against measurements taken in the current clinical scenario (circular collimators + clinical optics). Results: From the BDSIM simulations, we found that the new collimator system and matching beam optics results in an overall transmission from the cyclotron to the isocenter for a 70 MeV beam of 0.72%. This is an improvement of almost a factor of 6 over the current clinical performance (0.13% transmission). The new optics satisfies clinical beam requirements at the isocenter. Conclusions: We developed a new emittance collimation system for PSI's PROSCAN beamline which, by carefully selecting beam size and divergence asymmetrically, increases the beam transmission for low-energy beams in current state-of -the-art cyclotron-based proton therapy gantries. With theseThis is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

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“…The energy selection system prototype has been designed to work in the energy range between 70 MeV and 200 MeV allowing to select a beam with an energy spread ranging from 0.193% to 1.93% according to the transmission efficiency that one wants to achieve [9]. The proton beam extracted from a superconducting cyclotron is focused at the degrader, by passing it through four quadrupole magnets (QM01-QM04).…”

Section: Introductionmentioning

confidence: 99%

“…At the movable slit, the correlation between the momentum spread and the horizontal distance(x) was calculated by the computer code TURTLE and TRANSPORT. The position dispersion coefficient R16 is −27.54 mm/% [9].…”

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confidence: 99%

Analysis and Design of an Energy Verification System for SC200 Proton Therapy Facility

et al. 2019

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The purpose of this study is to provide an energy verification method for the nozzle of the SC200 proton therapy facility to ensure safe redundancy of treatment. This paper first introduces the composition of the energy selection system of the SC200 proton therapy facility. Secondly, according to IEC60601 standard, the energy verification requirement that correspond to 1 mm error in water is presented. The allowable difference between the measured magnetic field and the reference are calculated based on the energy verification requirements to select the field resolution of the Hall probe. To ensure accuracy and stability, two Hall probes are mounted on the dipole to monitor the magnetic field strength to verify the proton beam energy in real time. In addition, the test results of the residual field of the dipole show that the probe system meets the accuracy requirements of energy verification. Furthermore, the maximum width of the slit of the energy selection system in accordance with the IEC standard at the corresponding energy is calculated and compared with the actual position of the movable slit to verify the momentum divergence of the proton beam. Finally, we present an energy verification method.

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Beam optics study for energy selection system of SC200 superconducting proton cyclotron

Cited by 10 publications

References 8 publications

Beam characterisation studies of the 62 MeV proton therapy beamline at the Clatterbridge Cancer Centre

Beam characterisation studies of the 62 MeV proton therapy beamline at the Clatterbridge Cancer Centre

A new emittance selection system to maximize beam transmission for low‐energy beams in cyclotron‐based proton therapy facilities with gantry

Analysis and Design of an Energy Verification System for SC200 Proton Therapy Facility

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