Fast and precise verification of proton beam position, range, and dose using a plastic scintillator at PET-dedicated cyclotrons

The number of cyclotrons capable of accelerating protons to about 20MeV is increasing throughout the world. Originally aiming at the production of positron emission tomography (PET) radionuclides, some of these facilities are equipped with several beam lines suitable for scientific research. Radiobiology, radiophysiology, and other dosimetric studies can be performed using these beam lines. In this work, we report on experimental results and SRIM/TRIM simulations, which aim at measuring the Bragg peak of the 18 -MeV proton beam from the PET cyclotron. By using a piece of plastic scintillator and a D-link Ethernet-based camera, we measured the proton beam range and width with a spatial resolution of 0.1mm. The relation between the intensity of the scintillation light, which was generated by irradiation with the proton beam, and the cyclotron stripper current shows good linearity below 0.6 μA. In addition, we plotted the stability of the proton beam range within the scintillator block. The ranges of the proton beam in the plastic scintillator were used to assess its energy after trespassing one or two Havar windows and either a 40-cm-long or a 2.4-m-long aluminum pipe. The initial energy of the proton beam from the PET cyclotron was found to be 18MeV. The dose calculation follows immediately by taking into consideration the total beam current delivered on a target, which was measured by means of a thin aluminum foil trespassed by the beam and readout by in-house made transimpedance amplifiers.