Head CBCT vs head MSCT imaging; comparing organ doses and radiation risks for a cohort of orthognathic patients

Abstract

Introduction In oral and maxillofacial surgery, a preoperative-full-head-scan is required for treatment planning purposes. Orthognathic patients are traditionally referred to radiology departments for a head CT scan. However, state-of-the-art dental-CBCT-scanners, equipped with large detectors and/or stitching and offset-scanning-methods, enable full head image acquisitions. Purpose to calculate organ doses and estimate radiation risks for patients undergoing head-CT and full skull dental-CBCT exams. Materials and methods An EGSnrc-based Monte-Carlo (MC) dosimetry tool was used to calculate organ doses in the reference ICRP-female-voxel-phantom for skull protocols in two dental-CBCT-scanners. Promax-3D-Max (Planmeca, FI) employs a 230 × 260 mm 2 FOV (diameter × height) using a stitching technique and fixed current during rotation. VGi-evo (Newtom, IT) employs a 240 × 190 mm 2 FOV and tube current (TCM) modulation. An anthropomorphic phantom (SK 150, The Phantom Laboratory) was scanned to extract the TCM curve which was then employed to the framework in terms of dose-integral-weighting-factors. CT-Expo v2.2 was used to calculate organ and effective doses for ten adult females, undergone head CTs in an Aquilion One (Toshiba, Japan) and a Somatom Definition Flash (Siemens, DE) scanner. Results The effective dose (ED) for Promax-3D-Max ranges from 85 to 1090 μSv depending on the operation mode (mAs-settings), whereas for VGI-evo the ED was 265 μSv. For head CT the ED ranges from 1.3 to 1.9 mSv. In all cases the highest doses were observed to salivary glands, oral mucosa, ET, brain, thyroid and RBM. Conclusion Dosewise, full-head-dental-CBCT scans demonstrate significantly lower organ doses and lower ED compared to MSCT scanners. Disclosure Nothing to disclose.