CYCLOTRONS2022 - List of Authors (Schippers, J.M.)

Paper	Title	Page
THBO03	Implementation of Accurate Dose Delivery Control at FLASH Dose Rates at PARTREC
	M.J. Goethem, S. Both, S. Brandenburg, A. Gerbershagen, J.M. Schippers, M. Xiao, R.J.C. de Koster PARTREC, Groningen, The Netherlands
	The University Medical Center Groningen (UMCG) and the University of Groningen (UoG) have recently established the Particle Therapy Research Center (PARTREC) for accelerator based research on radiobiology and instrumentation for particle therapy. PARTREC uses the AGOR cyclotron to produce proton beam (up to 190 MeV) and heavy ion (helium/carbon) beams (up to 90 MeV/u). The facility builds upon previous expertise in accelerator physics, instrumentation and radiobiology of the KVI-CART institute. In recent years the use of high dose rate hypo fractionated treatment of cancer (FLASH) has become a topic of high interest to the radiobiology and particle therapy community because of its potential to reduce damage to normal tissues as compared to conventional treatment while not affecting the tumor control [1]. We report on the development of a flexible dose delivery system for FLASH research allowing proton irradiations at dose rates of 40 Gy/s to 100 Gy/s. The field is produced using scattering or (spot)scanning. The system allows to introduce beam time structure ranging from approx. 5-µs pulses with a frequency up to 1 kHz up to a CW dose delivery. This flexibility also allows us to generate TWIN FLASH BEAMS, which reproduce the spatial and time structure as used at clinical proton facilities that can affect the FLASH effect. A TWIN BEAM facilitates a fast translation of technical developments and pre-clinical radiobiology research to the clinic. The aim is to have the facility available for radiobiology experiments beginning of 2023. In parallel we are also working on beam/control and monitoring techniques to increase the dose rate in the direction of 1000 Gy/s. For this purpose we are investigating new beam monitoring techniques, for example the CWCT from Bergoz [2]. And we will work on connecting dosimetry at low dose rate with that at high dose rate. [1] E. Diffenderfer et al. DOI: 10.1002/mp.15276 [2] M. Xiao et al. https://ibic2022.vrws.de/papers/mop33.pdf
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WEAO01	OPAL Simulation on the Beam Transmission in the Central Region of the Medical Cyclotron COMET at Paul Scherrer Institute	148
	H. Zhang, C. Baumgarten, P. Frey, M. Hartmann, R. Kan, M. Kostezer, A. Mülhaupt, J.M. Schippers, A. Schmidt, J. Snuverink PSI, Villigen PSI, Switzerland
	The use of the medical cyclotron COMET for FLASH proton therapy requires a high beam transmission from the ion source through the central region apertures. This paper first presents a model of the COMET cyclotron featuring a rotatable ion source, a movable puller, and an adjustable first fixed slit (FFS), implemented with the OPAL framework. The electromagnetic field is individual-ly created to match each specific configuration. The beam optics parameters, especially beam position and beam size upon approaching and after passing FFS, have been studied in detail. The OPAL simulations demon-strate that an optimal configuration of the ion source, the puller and the FFS is key to achieve a high beam trans-mission. An experimental test gave a 2.8 times higher intensity within COMET cyclotron with the modifications derived on the basis of the simulations: a 0.57 mm shift of puller and a 5.6° rotation of ion source. The simula-tions indicate that, with these modifications, the beam can still be centered and accelerated to the extraction energy of 250 MeV. Next step is to investigate the influ-ence of such modifications upon the acceleration and the extraction, again with an iterative approach combining simulations and experiments.
	Slides WEAO01 [5.351 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-CYCLOTRONS2022-WEAO01
About •	Received ※ 13 December 2022 — Revised ※ 09 January 2023 — Accepted ※ 01 February 2023 — Issue date ※ 11 March 2023
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THBO04	Accelerators for Medical Application: What Is So Special
	J.M. Schippers PSI, Villigen PSI, Switzerland
	The specific requirements of accelerators for radiation therapy will be discussed. After an introduction on the dose delivery method and the specially needed equipment in proton therapy, operational aspects will be discussed as well as their relation to formal aspects like certification. There will be a focus on the special requirements to reach a high reliability for patient treatments, so on an accurate delivery of the dose at the correct position in the patient using modern techniques like pencil beam scanning. It will be shown that the requirements of the beam are quite different from those in a nuclear physics laboratory. One needs very high requirements on beam intensity and stability to achieve the correct absolute dose and to minimize activation. Since an irradiation treatment cannot be interrupted during the approximately six weeks a patient treatment lasts, it is of utmost importance to have only short and well planned shutdowns for service. The way of operating a medical device requires not only operators, but also the possibility to have a safe machine operation by non accelerator specialists.
	Slides THBO04 [6.366 MB]
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FRBI01	Different Methods to Increase the Transmission in Cyclotron-Based Proton Therapy Facilities	368
	V. Maradia, A.L. Lomax, D. Meer, S. Psoroulas, J.M. Schippers, D.C. Weber PSI, Villigen PSI, Switzerland
	Funding: This work is supported by a PSI inter-departmental funding initiative (Cross) In proton therapy (PT), high dose rates could allow efficient utilization of motion mitigation techniques for moving targets, and potentially enhance normal tissue sparing due to the FLASH effect. Cyclotrons are currently the most common accelerator for PT, accounting for two-thirds of the total installations. However, for cyclotron-based facilities, high dose rates are difficult to reach for low-energy beams, which are generated by passing a high-energy beam through an energy degrader and an energy selection system (ESS); due to scattering and range straggling in the degrader, the emittance and energy/momentum spread increase significantly, incurring large losses from the cyclotron to the patient position. To solve these problems, we propose two approaches: a) transporting the maximum acceptable emittance in both transverse planes (using asymmetric collimators and/or scattering foil); b) an ESS with a wedge (instead of slits), reducing the momentum spread of the beam without significant beam losses. We demonstrate in simulation that low-energy beam transmission can be increased up to a factor of 60 using these approaches compared to the currently used beamline and ESS. This concept is key to enhance the potential of proton therapy by increasing the possibilities to treat new indications in current and future proton therapy facilities while reducing the cost.
	Slides FRBI01 [7.811 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-CYCLOTRONS2022-FRBI01
About •	Received ※ 12 January 2023 — Revised ※ 28 January 2023 — Accepted ※ 31 January 2023 — Issue date ※ 19 May 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

THBO03

Implementation of Accurate Dose Delivery Control at FLASH Dose Rates at PARTREC

M.J. Goethem, S. Both, S. Brandenburg, A. Gerbershagen, J.M. Schippers, M. Xiao, R.J.C. de Koster
PARTREC, Groningen, The Netherlands

The University Medical Center Groningen (UMCG) and the University of Groningen (UoG) have recently established the Particle Therapy Research Center (PARTREC) for accelerator based research on radiobiology and instrumentation for particle therapy. PARTREC uses the AGOR cyclotron to produce proton beam (up to 190 MeV) and heavy ion (helium/carbon) beams (up to 90 MeV/u). The facility builds upon previous expertise in accelerator physics, instrumentation and radiobiology of the KVI-CART institute. In recent years the use of high dose rate hypo fractionated treatment of cancer (FLASH) has become a topic of high interest to the radiobiology and particle therapy community because of its potential to reduce damage to normal tissues as compared to conventional treatment while not affecting the tumor control [1]. We report on the development of a flexible dose delivery system for FLASH research allowing proton irradiations at dose rates of 40 Gy/s to 100 Gy/s. The field is produced using scattering or (spot)scanning. The system allows to introduce beam time structure ranging from approx. 5-µs pulses with a frequency up to 1 kHz up to a CW dose delivery. This flexibility also allows us to generate TWIN FLASH BEAMS, which reproduce the spatial and time structure as used at clinical proton facilities that can affect the FLASH effect. A TWIN BEAM facilitates a fast translation of technical developments and pre-clinical radiobiology research to the clinic. The aim is to have the facility available for radiobiology experiments beginning of 2023. In parallel we are also working on beam/control and monitoring techniques to increase the dose rate in the direction of 1000 Gy/s. For this purpose we are investigating new beam monitoring techniques, for example the CWCT from Bergoz [2]. And we will work on connecting dosimetry at low dose rate with that at high dose rate. [1] E. Diffenderfer et al. DOI: 10.1002/mp.15276 [2] M. Xiao et al. https://ibic2022.vrws.de/papers/mop33.pdf

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEAO01

OPAL Simulation on the Beam Transmission in the Central Region of the Medical Cyclotron COMET at Paul Scherrer Institute

148

H. Zhang, C. Baumgarten, P. Frey, M. Hartmann, R. Kan, M. Kostezer, A. Mülhaupt, J.M. Schippers, A. Schmidt, J. Snuverink
PSI, Villigen PSI, Switzerland

The use of the medical cyclotron COMET for FLASH proton therapy requires a high beam transmission from the ion source through the central region apertures. This paper first presents a model of the COMET cyclotron featuring a rotatable ion source, a movable puller, and an adjustable first fixed slit (FFS), implemented with the OPAL framework. The electromagnetic field is individual-ly created to match each specific configuration. The beam optics parameters, especially beam position and beam size upon approaching and after passing FFS, have been studied in detail. The OPAL simulations demon-strate that an optimal configuration of the ion source, the puller and the FFS is key to achieve a high beam trans-mission. An experimental test gave a 2.8 times higher intensity within COMET cyclotron with the modifications derived on the basis of the simulations: a 0.57 mm shift of puller and a 5.6° rotation of ion source. The simula-tions indicate that, with these modifications, the beam can still be centered and accelerated to the extraction energy of 250 MeV. Next step is to investigate the influ-ence of such modifications upon the acceleration and the extraction, again with an iterative approach combining simulations and experiments.

Slides WEAO01 [5.351 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-CYCLOTRONS2022-WEAO01

About •

Received ※ 13 December 2022 — Revised ※ 09 January 2023 — Accepted ※ 01 February 2023 — Issue date ※ 11 March 2023

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THBO04

Accelerators for Medical Application: What Is So Special

J.M. Schippers
PSI, Villigen PSI, Switzerland

The specific requirements of accelerators for radiation therapy will be discussed. After an introduction on the dose delivery method and the specially needed equipment in proton therapy, operational aspects will be discussed as well as their relation to formal aspects like certification. There will be a focus on the special requirements to reach a high reliability for patient treatments, so on an accurate delivery of the dose at the correct position in the patient using modern techniques like pencil beam scanning. It will be shown that the requirements of the beam are quite different from those in a nuclear physics laboratory. One needs very high requirements on beam intensity and stability to achieve the correct absolute dose and to minimize activation. Since an irradiation treatment cannot be interrupted during the approximately six weeks a patient treatment lasts, it is of utmost importance to have only short and well planned shutdowns for service. The way of operating a medical device requires not only operators, but also the possibility to have a safe machine operation by non accelerator specialists.

Slides THBO04 [6.366 MB]

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

FRBI01

Different Methods to Increase the Transmission in Cyclotron-Based Proton Therapy Facilities

368

V. Maradia, A.L. Lomax, D. Meer, S. Psoroulas, J.M. Schippers, D.C. Weber
PSI, Villigen PSI, Switzerland

Funding: This work is supported by a PSI inter-departmental funding initiative (Cross)
In proton therapy (PT), high dose rates could allow efficient utilization of motion mitigation techniques for moving targets, and potentially enhance normal tissue sparing due to the FLASH effect. Cyclotrons are currently the most common accelerator for PT, accounting for two-thirds of the total installations. However, for cyclotron-based facilities, high dose rates are difficult to reach for low-energy beams, which are generated by passing a high-energy beam through an energy degrader and an energy selection system (ESS); due to scattering and range straggling in the degrader, the emittance and energy/momentum spread increase significantly, incurring large losses from the cyclotron to the patient position. To solve these problems, we propose two approaches: a) transporting the maximum acceptable emittance in both transverse planes (using asymmetric collimators and/or scattering foil); b) an ESS with a wedge (instead of slits), reducing the momentum spread of the beam without significant beam losses. We demonstrate in simulation that low-energy beam transmission can be increased up to a factor of 60 using these approaches compared to the currently used beamline and ESS. This concept is key to enhance the potential of proton therapy by increasing the possibilities to treat new indications in current and future proton therapy facilities while reducing the cost.

Slides FRBI01 [7.811 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-CYCLOTRONS2022-FRBI01

About •

Received ※ 12 January 2023 — Revised ※ 28 January 2023 — Accepted ※ 31 January 2023 — Issue date ※ 19 May 2023

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)