Estimation of organ and effective doses for rotational cerebral angiography using the National Cancer Institute Dosimetry System for Radiography and Fluoroscopy (NCIRF).

Abstract

Rotational cerebral angiography requires accurate dosimetry. The National Cancer Institute Dosimetry System for Radiography and Fluoroscopy (NCIRF), a Monte Carlo-based dosimetry software, can evaluate the organ dose (OD) and effective dose (ED) with higher accuracy than the conventional Monte Carlo software (PCXMC). We estimated the OD and ED for three-dimensional digital subtraction angiography (3D-DSA) and cone beam computed tomography (CBCT) using the NCIRF, reflecting dose variations during rotational cerebral angiography. The 3D-DSA and CBCT simulation parameters were obtained by rotational imaging of a physical head phantom using the Artis Q biplane system. The air kerma area product for each projection was determined based on the ratio of the tube current-time product for each projection; the NCIRF was used with male and female voxel-type reference computational phantoms. To validate the simulation results, the lens dose of the phantom was measured using radiophotoluminescence glass dosimeters and compared to the simulated lens dose. The highest ODs were delivered to the brain: 8.8 mGy (males) and 11.6 mGy (females) in 3D-DSA and 50.0 mGy (males) and 59.4 mGy (females) in CBCT. The EDs were 0.27 mSv (males) and 0.35 mSv (females) in 3D-DSA and 1.49 mSv (males) and 1.83 mSv (females) in CBCT. Lens doses differed within 8.0% between measurements and simulations, with 45.9-65.5% overestimation in simulations that did not account for dose variability. Simulations that considered dose variability using the NCIRF more accurately estimated OD and ED in rotational cerebral angiography.