Evaluation of an optical scintillating fiber detector for CT dosimetry

Abstract Purpose The aim of this work is to compare the energy response of a scintillating fiber to that of standard detectors used for dose monitoring in Computed Tomography (CT) and confirm the validity of Plastic Scintillating Detectors in CT dosimetry. We also seek to model the scintillating fiber response in realistic irradiation conditions for future applications on a complete dose measurement system. For this, we have modeled an X-ray generator emission and validated the model using its measured X-rays spectrum. Materials and methods Irradiations were performed in an X-ray generator at voltage varying from 80 to 140 kV. The Plastic Scintillating Detector (PSD) was compared with a pencil ion chamber and Thermo-Luminescent Detectors (TLD). Monte Carlo simulations of each detector response were compared to measurements in order to validate the simulation in a simple case. Results The Monte Carlo simulations reproduced accurately the response of each detector with less than 3% and 5% of difference for the ion chamber and the TLDs respectively. When comparing the PSD with the two standard detectors, we observed that while the plastic scintillator detector and the ion chamber responses presented less than 5% discrepancy, they both were very different than TLDs response on the whole investigated energy range. The Monte Carlo simulation of the PSD reproduced accurately the response of the plastic scintillating detector with less than 3% of difference. Conclusion The X-ray spectrum has been accurately measured which allowed to successfully reproduce the energy response of the PSD using Monte Carlo simulations. Although this study proved that the scintillating fibers energy response is appropriate for CT dose measurement, further experiments must be performed in clinical conditions.