Charbel Bou Serhal Absorbed doses from spiral CT and Reinhilde Jacobs conventional spiral tomography: a Frieda Gijbels Hilde Bosmans phantom vs. cadaver study Robert Hermans Marc Quirynen Daniel van Steenberghe Authors’ affiliations: C. Bou Serhal, R. Jacobs, F. Gijbels, M. Quirynen, D. van Steenberghe*, Department of Periodontology, Oral Imaging Cluster, School of Dentistry, Oral Pathology and Maxillofacial Surgery, University Hospital, Catholic University Leuven H. Bosmans, R. Hermans, Department of Radiology, University Hospital, Catholic University Leuven, Leuven, Belgium * Holder of the P-I Brånemark chair in osseointegration Correspondence to: Reinhilde Jacobs, Department of Periodontology Oral Imaging Cluster Faculty of Medicine Catholic University of Leuven Kapucijnenvoer 7 3000 Leuven Belgium Tel: π32 16 33 29 51; Fax: π32 16 33 24 84 e-mail: reinhilde.jacobs/uz.kuleuven.ac.be Date: Accepted 23 October 2000 To cite this article: Bou Serhal C, Jacobs R, Gijbels F, Bosmans H, Hermans R, Quirynen M, van Steenberghe D. Absorbed doses from spiral CT and conventional spiral tomography: a phantom vs. cadaver study Clin. Oral Impl. Res. 12, 2001; 473–478 Copyright C Munksgaard 2001 ISSN 0905-7161 473 Key words: radiation dose, tomography, CT, thyroid gland, parotid gland, TLD dosimetry Abstract: For several radiological examinations, a clinician can select between conventional and spiral computed tomography. Using both techniques, this study aimed at evaluating the difference in absorbed doses when examining a single lateral jaw segment in a human cadaver head and Rando phantom. The present study involved the placement of thermoluminescent dosimeter (TLD) chips (GR-200) in the thyroid gland, and bilaterally, in the parotid and submandibular glands and the lenses of the eyes in both a human cadaver and a Rando phantom at corresponding locations. Consecutive conventional spiral tomographic examinations were carried out in both the left upper and lower premolar area, using a Cranex TOME A multifunctional unit. Each examination consisted of 4 slices with a 2 mm slice thickness and exposure parameters of 57 kV, 56 seconds and 1.6–2.0 mA. Regarding spiral computed tomography (CT), a Somatom Plus S A scanner (Siemens, Erlangen, Germany), with a slice thickness of 1 mm with settings at 120 kV and 165 mA, was used on both phantoms and separately in the upper and lower jaw. With conventional tomography, the findings of the present study showed that the parotid and submandibular glands on the side near the X-ray tube received the highest dose, both for the cadaver head (doses ranging from 0.5 to 1.3 mGy) and the phantom (doses ranging from 0.6 to 2.6 mGy). For CT of the upper jaw, the highest doses were delivered to the parotid glands with an average absorbed dose of 9.2 and 10.6 mGy for the cadaver head and phantom, respectively. The submandibular glands received the highest doses during CT examination of the lower jaw with an average of 7.8 and 12.9 mGy for the cadaver head and phantom, respectively. It appears from the present investigation that if small edentulous regions are examined, radiation doses during conventional tomography remain much lower than during CT imaging. However, when multiple tomographic cuts are required, a spiral CT examination can replace a series of conventional examinations, especially in cases such as the rehabilitation of an edentulous upper jaw or a more complex surgery. The use of specialised radiographic tech- niques (e.g. conventional or computed tomography) in the orofacial region has increased during the last decade espe- cially because of oral implant place- ment. It has been shown that cross-sec- tional imaging techniques are more re- liable than intra-oral or panoramic radiography for the preoperative plan- ning of oral implants, as it allows to visualise both bone structures and/or localise anatomical landmarks in 3 di- mensions (Jacobs & van Steenberghe 1998). This can improve the implant in- sertion with respect to biomechanical requirements and avoid injury to the neurovascular bundle within the man- dibular canal. Reformatted computed tomography (CT) has been considered as the method of choice (Quirynen et al.