In craniomaxillofacial computed tomography (CT) images may be obtained using substantially lower doses than the current diagnostic reference level (DRL) in sinus imaging of CTDIvol 8 mGy (Fig. 1) [1]. Purpose was to develop clinical DRLs for various diagnostic tasks using an as-low-as-diagnostically-acceptable (ALADA) image quality approach.

Several cadaver studies were performed in which reference images a Discovery CT750 HD scanner at CTDIvol of 29-37 mGy (DRLs for craniomaxillofacial and cranial CT are 20 mGy and 60 mGy, respectively) were compared with test images at doses reaching sub-mGy levels. Comparative quantitative measurements, visual grading analysis and receiver operating characteristics were performed. The influence of iterative reconstructions has been evaluated. The following ALADA doses could be identified for the subsequent indications: trauma 2.66 mGy [2-3] identification of the inferior alveolar nerve 2.64 mGy...

Based on the obtained ALADA doses, suggested clinical DRLs for craniomaxillofacial trauma and oral implant imaging may be 3 mGy which is less than half the dose of a current published DRL for sinus imaging. Future work may determine quality parameters from clinical ALADA protocols using standardized image quality phantoms. Reference quality metrics and comparative phantom testing may facilitate finding and ongoing improvement of ALADA doses and protocols for other manufacturers, scanners, and dose saving technology.

Gerlig Widmann, MD and Werner Jaschke, MD Tirol Klinken GmbH – Medical Universität of Innsbruck Department of Radiology Anichstr. 35 A-6020 Innsbruck e-mail: [email protected] Asma'a Al-Ekrish, MDS, Cert. Diag. Sci. King Saud University Riyadh, Saudi Arabia e-mail: [email protected]

[1] Widmann G, Schullian P, Gassner EM, Hoermann R, Bale R, Puelacher W. Ultralow-dose CT of the craniofacial bone for navigated surgery using adaptive statistical iterative reconstruction and model-based iterative reconstruction: 2D and 3D image quality. Ajr. 2015 Mar;204(3):563-9. [2] Widmann G, Dalla Torre D, Hoermann R, Schullian P, Gassner EM, Bale R, et al. Ultralow-dose computed tomography imaging for surgery of midfacial and orbital fractures using ASIR and MBIR. Int J Oral Maxillofac Surg. 2015 Apr;44(4):441-6. [3] Widmann G, Juranek D, Waldenberger F, Schullian...