On-line measurements of proton beam current from a PET cyclotron using a thin aluminum foil

Ghithan, Sharif; Carmo, S.J.C. do; Ferreira‐Marques, R.; Fraga, F.A.F.; Simoes, Hugo; Alves, Francisco; Crespo, Paulo

doi:10.1088/1748-0221/8/07/p07010

Cited by 5 publications

(7 citation statements)

References 12 publications

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“…In a first stage the proton beam was brought outside the yoke of the cyclotron using a 40-cmlong aluminum pipe (figure 1). The dose rate at this stage was assessed to be of the order of 5 kGy/s for minimum cyclotron currents [18]. In order to decrease this too-high dose rate value, a 2-m-long aluminum pipe was further attached to the first one (figure 1).…”

Section: Out-of-yoke Chopped Beammentioning

confidence: 99%

“…The measured dose rate at the end of the long pipe ranges from 1 kGy/s down to 10 Gy/s [18]. These dose rates are too high for radiobiology studies, and controlling them by a shutter that responds within fractions of a second to achieve irradiation of tens and hundreds of mGy, would not 2015 JINST 10 P02010 be possible.…”

Section: Out-of-yoke Chopped Beammentioning

confidence: 99%

“…The proton beam that passes through a 23 mm diameter hole positioned after the second Havar window trespasses a 20-µm-thick aluminum foil positioned in air immediately after this collimator. The beam current on target is assessed by measuring the current of the secondary electrons liberated (secondary current) from this thin aluminum foil (figure 3(a)) [18]. The 23-mm-diameter hole is covered at the outside by a piece of black foil (i.e., 0.14-mm-thick plastic foil) in order to prevent the secondary electrons liberated from the aluminum collimator and the second Havar R window from reaching the aluminum foil.…”

Section: Hardware and Software For Dose And Dose Rate Measurementsmentioning

confidence: 99%

“…A possible solution is the use of a thin aluminum foil (20-µm-thick), reading out by transimpedance electronics. the secondary electrons liberated from the thin aluminum foil when protons traverse it [18].…”

Section: Introductionmentioning

confidence: 99%

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Development of a PET cyclotron based irradiation setup for proton radiobiology

et al. 2015

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An out-of-yoke irradiation setup using the proton beam from a cyclotron that ordinary produces radioisotopes for positron emission tomography (PET) has been developed, characterized, calibrated and validated. The current from a 20 µm thick aluminum transmission foil is readout by home-made transimpedance electronics, providing online dose information. The main monitoring variables, delivered in real-time, include beam current, integrated charge and dose rate. Hence the dose and integrated current delivered at a given instant to an experimental setup can be computercontrolled with a shutter. In this work, we report on experimental results and Geant4 simulations of a setup which exploits for the first time the 18 MeV proton beam from a PET cyclotron to irradiate a selected region of a target using the developed irradiation system. By using this system, we are able to deliver a homogeneous beam on targets with 18 mm diameter, allowing to achieve the controlled irradiation of cell cultures located in biological multi-well dishes of 16 mm diameter. We found that the magnetic field applied inside the cyclotron plays a major role for achieving the referred to homogeneity. The quasi-Gaussian curve obtained by scanning the magnet current and measuring the corresponding dose rate must be measured before any irradiation procedure, with the shutter closed. At the optimum magnet current, which corresponds to the center of the Gaussian, a homogenous dose is observed over the whole target area. Making use of a rotating disk with a slit of 0.5 mm at a radius of 150 mm, we could measure dose rates on target ranging from 500 mGy/s down to 5 mGy/s. For validating the developed irradiation setup, several Gafchromic R EBT2 films were exposed to different values of dose. The absolute dose in the irradiated films were assessed in the 2D film dosimetry system of the Department of Radiotherapy of Coimbra University Hospital Center with a precision better than 2%. In the future, we plan to irradiate small animals, cell cultures, or other materials or samples.

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Section: Out-of-yoke Chopped Beammentioning

confidence: 99%

Section: Out-of-yoke Chopped Beammentioning

confidence: 99%

Section: Hardware and Software For Dose And Dose Rate Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Development of a PET cyclotron based irradiation setup for proton radiobiology

et al. 2015

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“…Proton beam currents during radioisotope productions can range up to 150 µA . Proton beam currents of 2 nA with a proton energy of 15.2 MeV have been assessed by Ghithan et al to generate dose rates in the order of 5 kGy/s in the Bragg peak region.…”

Section: Introductionmentioning

confidence: 99%

Design and verification of an external radiobiological beam port on a 16.5 MeV GE PETtrace proton cyclotron

et al. 2019

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Purpose Protons and heavy ions are considered to be ideal particles for use in external beam radiotherapy due to the superior properties of the dose distribution. While a photon (x‐ray) beam delivers considerable dose to healthy tissues around the tumor, a proton beam that is delivered with sufficient energies has: a low entrance dose (the dose in front of the tumor); a high‐dose region within the tumor, known as the Bragg peak; and, no exit dose beyond the tumor. Proton therapy is the next major step in advancing radiotherapy treatment. The purpose of this project was to adapt an existing radioisotope production cyclotron, a General Electric (GE) PETtrace, to enable radiobiological studies using proton beams. During routine use the PETtrace delivers 16.5 MeV protons to target with beam currents in the range of 10–100 µA resulting in dose rates in the order of kGy/s. To achieve the aim of the project the dose rate had to be reduced to the Gy/min range, without attenuating the proton energy below 5 MeV. This paper covers the design, construction and validation of the beam port. Methods Monte Carlo simulations were performed, using GEANT4, SRIM and PACE4 to design the beam port and optimize its components. Once the beam port was fabricated, validation experiments were performed using EBT3 and HD‐V2 Gafchromic™ films, and a Keithley 6485 picoampere meter. Results and conclusion The external beam port was successfully modeled, designed and fabricated. By using a 0.25 mm thick gold foil and a brass pin‐hole collimator the beam was spread from a narrow full beam diameter of 10 mm to a wide beam with a 5% flatness area in the center of the beam that had a diameter of ~20 mm. In using this system the dose rate was reduced from kGy/s to ~30 Gy/min.

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Central region of SKKUCY-9 compact cyclotron

Jung¹,

Kim²,

Ghergherehchi³

et al. 2014

J. Inst.

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The development of a 9 MeV compact cyclotron for the production of radioisotopes for medical applications has been recently completed. The machine accelerates negative hydrogen ions generated from an internal PIG (Penning Ion Gauge) ion source following spiral orbits. Some of the structures designed for early beam acceleration, including a pair of center poles providing ions a circular direction, the head of the ion source, and the electrodes, are located in the center of the cyclotron. In this paper we discuss and evaluate the design of the central region that pulls the ions from the chimney of the ion source and directs them into the equilibrium orbit. The magnetic field produced by the center poles was analyzed using the magnetic solver in OPERA-3D TOSCA, and the phase error and ion equilibrium orbit, which is dependent on the kinetic energy within the designed field, were calculated using CYCLONE v8.4. The electric field produced in the acceleration gap was designed using an electrostatic solver. Then, the single beam trajectory was calculated by our own Cyclotron Beam Dynamics (CBD) code. The early orbits, vertical oscillation, acceptable RF phase and the energy gain during the early turns was evaluated. Final goal was to design the central region by the iterative optimization process and verify it with 1 MeV beam experiment.

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On-line measurements of proton beam current from a PET cyclotron using a thin aluminum foil

Cited by 5 publications

References 12 publications

Development of a PET cyclotron based irradiation setup for proton radiobiology

Development of a PET cyclotron based irradiation setup for proton radiobiology

Design and verification of an external radiobiological beam port on a 16.5 MeV GE PETtrace proton cyclotron

Central region of SKKUCY-9 compact cyclotron

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