Photon energy estimation in diagnostic radiology using OSL dosimeters: Experimental validation and Monte Carlo simulations

The EGSnrc Monte Carlo software toolkit was used to evaluate the energy response and estimate the photon energy based on the E3/E4 ratio for the InLight XA Optical Luminescence Dosimeters (OSLDs).

The InLight XA OSLDs were irradiated with Cs-137 source and ISO 4037-1 narrow-spectrum series X-ray qualities (N40, N60, N80, and N100). The virtual OSLDs on the surface of the PMMA phantom were constructed in EGSnrc, energy response and ratio E3/E4 of the dosimeters was determined and compared to the physical measurements.

Good agreement was found between the simulated and measurement approaches in estimating the photon energy with a percentage difference of less than 6%. The E3/E4 ratio from simulation, physical measurements, and microStar system showed very good agreement results with the maximum difference of 9.3% and 10.94%, respectively. Furthermore, the OSLDs energy response varied significantly at energy below 100 keV due to the photoelectric effect.

The results of this study identify and address the over-response of OSLDs to low-energy photons, offering correction factors to minimize errors, especially in diagnostic radiology applications. These findings have the potential to improve dose accuracy for patients and radiation workers by providing more precise photon energy estimations, particularly at lower energy ranges, such as in diagnostic X-rays. The function used to evaluate photon energy using E3/E4 ratio has a great influence on the accuracy of such algorithms. It also ensures that imaging equipment is properly calibrated for the specific energy ranges needed, enhancing diagnostic accuracy. Furthermore, precise dose measurements are essential for maintaining regulatory compliance and long-term patient exposure records, ultimately promoting safer and more effective radiological practices.