ИСТИНА

Introduction: In November 2015 the first domestic complex of proton therapy "Prometheus" start to treat oncology patients. This complex uses a modern technique for irradiation of tumors by scanning with a pencil beam. This technique requires continuous monitoring and regular verification of main beam parameters such as range in water, focusing and lateral dimension. To control these parameters, we developed a waterproof detector for measurements in air and in a water phantom. Methods and materials: The detector system consists of a luminescent screen 5 cm in diameter, a mirror and a CCD camera. When the beam goes through the screen, a glow appears, the reflected image of which is perceived by the camera and analyzed. This design is waterproof, which makes it possible to perform measurements in water. To measure the range of protons in water, this detector was fixed on a special positioner, which allows to move the sensor with an accuracy of 0.2 mm. We measured the beams also in comparison with EBT3 dosimetric film for energies from 60 to 250 MeV with a step of 10 MeV. Same measurements of the ranges were carried out using a standard PTW Bragg Peak ionization chamber. Results: It was shown that this system is a simple and inexpensive tool for conducting regular quality assurance of beam parameters. Unlike the EBT3 dosimetric film, this detector gives an immediate response, which makes it possible to use it when debugging the accelerator and adjusting the beam.