Dental and maxillofacial cone beam computed tomography absorbed dose distribution calculation by GEANT4

摘要

Absorbed dose distributions in dental and maxillofacial cone beam computed tomography (dental CBCT) are essential to dental CBCT dose indices. Direct measurements by thermoluminescence detectors are laborious. We establish a valid GEANT4 based absorbed dose simulation program with mean deviation being 7.25% compared to experimental measurements. Dental CBCT absorbed dose distributions simulated by this program indicate: The distributions are not always symmetry; Non-symmetry cases are when phantom center is departured from isocenter, half-fan beam with 360° scan angle range and some case full-fan beam with less than 360° scan angle range; Dose index weights for circular symmetry absorbed dose distributions are quite different for fields of view diameter bigger and smaller than phantom diameter.