Impact of voxel size on hand dose calculations and dose-area histogram analysis for radiopharmaceutical operators

This study evaluated the impact of voxel size on three-dimensional (3D) hand dose distributions and maximum dose estimates for radiopharmaceutical operators and examined the relationship between dose-area histogram (DAH) indices and the maximum mean skin dose over 1 cm² ([Formula: see text]). Dose distributions in a hand phantom during administration with a shielded syringe containing ^99mTc, ¹⁷⁷Lu, or ¹⁸F were calculated using Monte Carlo simulations. The hand phantom voxel size was varied from 1 to 5 mm, and skin-dose distributions on the finger surface were calculated using 1 mm × 1 mm × 10 μm voxels placed at a depth of 70 μm. DAHs and [Formula: see text] were evaluated for the index finger, middle finger, and thumb. With a 1 mm voxel size, the maximum dose occurred in the index and middle fingers for all radionuclides. At larger voxel sizes, dose underestimation due to the partial-volume effect was more pronounced in these fingers, where the dose gradient was steep, and the maximum-dose region shifted to the thumb at voxel sizes of 4 mm for ^99mTc and ¹⁷⁷Lu and 5 mm for ¹⁸F. Under most conditions, the minimum dose covering 0.6 cm² ([Formula: see text]) agreed with [Formula: see text] within ± 5%. These results indicate that the smallest feasible voxel size should be used for hand dose calculations, particularly for lower radionuclide energy and smaller source volume. DAH analysis may provide a simple and robust approach for estimating [Formula: see text] and assessing radiation-induced skin injury risk while accounting for the area effect.