SU‐E‐T‐69: Energy Response Characterization and Calibration of Electronic Personal Dosimeters

Purpose: To characterize the personal dose equivalent energy response, Hp(10), for electronic personal dosimeters (EPDs) with commonly used radionuclides in nuclear medicine. Methods: Rados‐60R with an energy compensated PIN diode and the SAIC Pd‐10i with a miniature energy compensated Geiger‐Muller tube EPDs were characterized. The experimental setup and calculation of EPD energy responses were based on ANSI/HPS N13.11‐2009. 15 Rados‐60R and 2 SAIC Pd‐10i units were irradiated using 99mTc, 131I, and 18F radionuclides corresponding to emission energies at 140 keV, 364 keV, and 511 keV, respectively. EPDs output in Hp(10) [mrem] were recorded for free‐in‐air and with 15‐in. thick PMMA to simulate backscatter form the torso. Simultaneous exposure rate measurements were also performed using 2 Victoreen 451‐B ionization survey meters to serve as gold standard measurements. The expected EPD Hp(10) values were calculated from exposure (from the Victoreen 451‐B survey meters) to Hp(10) as specified in ANSI/HPS N13.11‐2009 and ICRU Report 57. These measurements were repeated for both setups at all energies. Results: On average, in the presence of acrylic, the reported Rados‐60R values increased by 27%, 12%, and 13% and those reported by the SAIC Pd‐10i increased by 23%, 19%, and 12% at 140 keV, 364 keV, and 511 keV, respectively. The Rados‐60R EPDs were observed to under‐respond at 140 keV by ∼16%, and agreed to within 5% and 10% of the expected values at 364 and 511 keV, respectively. The SAIC Pd‐10i EPDs were observed to over‐respond at 140 keV by ∼20%, and agreed to within 5% of the expected values 364 and 511 keV. Conclusion: Both Rados‐60R and SAICPD‐10i EPDs displayed Hp(10) values that were accurate to within 10% at energies above 364 keV. However, their accuracies degraded to 15–20% at lower energies (140 keV) suggesting the need to calculate energy dependent correction factors.