Development of an Active-Type Optically Stimulated Luminescence (OSL) Dosimeter for Real-Time Dose Measurement of Diagnostic X-Rays

Active-type radiation dosimeters can measure list-mode datasets related to the measurement time and exposure dose, which contribute to detailed analysis of radiation exposure for patients and clinical staff. The aim of this study is to develop a compact active-type dosimeter based on an optically stimulated luminescence (OSL) system, and to establish a dose measurement procedure for diagnostic X-rays. The proposed dosimeter consists of an OSL sheet made of Al2O3:C and a multi-pixel photon counter (MPPC), and the detector region dimension is 10 mm × 10 mm × 13 mm. List-mode datasets consisting of measurement time and pulse height were recorded. The accumulated signal was analyzed by integrating the pulse-height data, in which the processing for smoothing, recovery-time correction, and counting-loss correction were performed. A dose calibration curve was determined from the integrated signal and reference air kerma measured with an ionization chamber. System performance was evaluated using diagnostic X-ray equipment under various dose rate conditions: a tube voltage of 80 kV, tube currents of 20–160 mA, and an exposure time of 1.0 s. Clinical applicability was also verified under typical exposure conditions for hand (50 kV), abdominal (80 kV), and chest (120 kV) examinations. In the experimental results, it was found that the proposed dosimeter can appropriately measure list-mode datasets and determine the accumulated dose with an accuracy of ±20% for 0.3–10 mGy/s. These findings indicate that the proposed dosimeter can be used for clinical dosimetry during diagnostic X-ray examinations.