Speaker
Description
A detector system for the purpose of quality assurance in radiation therapy is being developed and test measurements are presented. It is based on a beryllium oxide probe coupled to an optical fiber. Radioluminescence in the material generates photons, whose number is proportional to the dose absorbed in the probe. The photons are detected by very sensitive time resolving single photon counting heads. Diameter and height of the beryllium oxide probe amount 1 mm. Results from proton fields and pulsed x-ray fields approaching FLASH conditions are presented. With rising linear energy transfer, saturation effects in the light signal occur. In consequence, the measuring signal is not proportional to the reference dose and needs to be corrected. For this purpose, spectral changes of the radioluminescence photons were used to set up a correction factor. Hereby, it was possible to achieve a deviation of 2.3 % compared to an ionization chamber.
