Automated cyclotron tuning using beam phase measurements

Timmer, Jan; Röcken, H.; Stephani, T.; Baumgarten, C.; Geisler, A.

doi:10.1016/j.nima.2006.08.005

Cited by 9 publications

(8 citation statements)

References 2 publications

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“…For the beam to be considered pulsed or pulsed‐scanned, the pulse duration must be short compared to ion transit time in the given volume of an ion chamber (∼10 −6 s in Advanced Markus or PPC05), whereas the pulse‐to‐pulse interval or pulse repetition rate must be slow enough so that ionization events clear out among pulses. The ProBeam cyclotron produces 250‐MeV proton bunches with 0.2‐ns pulse duration at 72.8‐MHz RF repetition rate corresponding to 0.2‐ns micro‐pulses separated by 13.7‐ns intervals 18 . For the case of a PBS system, the beam is delivered in so‐called spots where hundreds of pulses in a single spot occur during the ion transit time; each spot is delivered in relatively large time scales (10 −3 s) and is then magnetically scanned across the plane perpendicular to the beam direction.…”

Section: Methodsmentioning

confidence: 99%

“…The ProBeam cyclotron produces 250-MeV proton bunches with 0.2-ns pulse duration at 72.8-MHz RF repetition rate corresponding to 0.2-ns micro-pulses separated by 13.7-ns intervals. 18 For the case of a PBS system, the beam is delivered in so-called spots where hundreds of pulses in a single spot occur during the ion transit time; each spot is delivered in relatively large time scales (10 −3 s) and is then magnetically scanned across the plane perpendicular to the beam direction. Therefore, the ProBeam PBS beam may be approximated to be continuous regarding ion recombination effects.…”

Section: Ion Recombination Measurementsmentioning

confidence: 99%

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Ultrahigh dose rate pencil beam scanning proton dosimetry using ion chambers and a calorimeter in support of first in‐human FLASH clinical trial

et al. 2022

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To provide ultrahigh dose rate (UHDR) pencil beam scanning (PBS) proton dosimetry comparison of clinically used plane-parallel ion chambers, PTW (Physikalisch-Technische Werkstaetten) Advanced Markus and IBA (Ion Beam Application) PPC05, with a proton graphite calorimeter in a support of first in-human proton FLASH clinical trial. Methods: Absolute dose measurement intercomparison of the plane-parallel plate ion chambers and the proton graphite calorimeter was performed at 5-cm water-equivalent depth using rectangular 250-MeV single-layer treatment plans designed for the first in-human FLASH clinical trial. The dose rate for each field was designed to remain above 60 Gy/s. The ion recombination effects of the plane-parallel plate ion chambers at various bias voltages were also investigated in the range of dose rates between 5 and 60 Gy/s. Two independent model-based extrapolation methods were used to calculate the ion recombination correction factors k s to compare with the two-voltage technique from most widely used clinical protocols. Results: The mean measured dose to water with the proton graphite calorimeter across all the predefined fields is 7.702 ± 0.037 Gy. The average ratio over the predefined fields of the PTW Advanced Markus chamber dose to the calorimeter reference dose is 1.002 ± 0.007, whereas the IBA PPC05 chamber shows ∼3% higher reading of 1.033 ± 0.007. The relative differences in the k s values determined from between the linear and quadratic extrapolation methods and the two-voltage technique for the PTW Advanced Markus chamber are not statistically significant, and the trends of dose rate dependence are similar. The IBA PPC05 shows a flat response in terms of ion recombination effects based on the k s values calculated using the two-voltage technique. Differences in k s values for the PPC05 between the two-voltage technique and other modelbased extrapolation methods are not statistically significant at FLASH dose rates. Some of the k s values for the PPC05 that were extrapolated from the three-voltage linear method and the semiempirical model were reported less than unity possibly due to the charge multiplication effect, which was negligible compared to the volume recombination effect in FLASH dose rates. Conclusions: The absolute dose measurements of both PTW Advanced Markus and IBA PPC05 chambers are in a good agreement with the NationalThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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Section: Methodsmentioning

confidence: 99%

Section: Ion Recombination Measurementsmentioning

confidence: 99%

Ultrahigh dose rate pencil beam scanning proton dosimetry using ion chambers and a calorimeter in support of first in‐human FLASH clinical trial

et al. 2022

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“…Any changes in the beam phase are compensated by a correction of the main coil current (Timmer et al, 2006). Its guidance is based on the precisely shimmed magnetic field and needs no further active correction elements.…”

Section: Magnet Systemmentioning

confidence: 99%

Cyclotrons

Goto¹

2014

Comprehensive Biomedical Physics

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“…It allows for instance to make precise online field measurements by NMR-probes. The results could be used to stabilize the magnetic field without beam extraction as it is required for a phase probe 16 . This would not only reduce start up time and simplify beam quality management, but it might also reduce activation of an external beam dump.…”

Section: A Variable Energy Cyclotron For Proton Therapymentioning

confidence: 99%

Cyclotrons with fast variable and/or multiple energy extraction

Baumgarten

2013

Phys. Rev. ST Accel. Beams

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We discuss the principle possibility of stripping extraction in combination with reverse bends in isochronous separate sector cyclotrons (and/or FFAGs). If one uses reverse bends between the sectors (instead of drifts) and places stripper foils at the sector exit edges, the stripped beam has a reduced bending radius and it should be able to leave the cyclotron within the range of the reverse bend -even if the beam is stripped at less than full energy.We are especially interested in H + 2 -cyclotrons, which allow to double the charge to mass ratio by stripping. However the principle could be applied to other ions or ionized molecules as well. For the production of proton beams by stripping extraction of an H + 2 -beam, we discuss possible designs for three types of machines: First a low-energy cyclotron for the simultaneous production of several beams at multiple energies -for instance 15 MeV, 30 MeV and 70 MeV -thus allowing to have beam on several isotope production targets. In this case it is desired to have a strong energy dependence of the direction of the extracted beam thus allowing to run multiple target stations simultaneously. Second we consider a fast variable energy proton machine for cancer therapy that should allow extraction (of the complete beam) at all energies in the range of about 70 MeV to about 250 MeV into the same beam line. And third, we consider a high intensity high energy machine, where the main design goals are extraction with low losses, low activation of components and high reliability. Especially if such a machine is considered for an accelerator driven system (ADS), this extraction mechanism has severe advantages: Beam trips by the failure of electrostatic elements could be avoided and the turn separation could be reduced, thus allowing to operate at lower main cavity voltages. This would in turn reduce the number of RF-trips.The price that has to be paid for these advantages is an increase in size and/or in field strength compared to proton machines with standard extraction at the final energy.

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Automated cyclotron tuning using beam phase measurements

Cited by 9 publications

References 2 publications

Ultrahigh dose rate pencil beam scanning proton dosimetry using ion chambers and a calorimeter in support of first in‐human FLASH clinical trial

Ultrahigh dose rate pencil beam scanning proton dosimetry using ion chambers and a calorimeter in support of first in‐human FLASH clinical trial

Cyclotrons

Cyclotrons with fast variable and/or multiple energy extraction

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