Patient dose in CT is usually expressed in terms of organ dose and effective dose. The latter is used as a measure of the stochastic risk. Determination of these doses by measurements or calculations can be time-consuming. We investigated the efficacy of physical dose quantities to describe the organ dose and effective dose. For various CT examinations of the head, neck and trunk, organ doses and effective doses were determined using conversion factors. Dose free-in-air on the axis of rotation (Dair) and weighted computed tomography dose index (CTDIw) were compared with the absorbed doses of organs which are located totally within the body region examined. Dose-length product (DLP) was compared with the effective dose. The ratio of the organ dose to CTDIw was 1.37 (0.87-1.79) mSv mGy-1. DLP showed a significant correlation with the effective dose (p < 0.005). The average ratio of effective dose to DLP was 0.28 x 10(-2) mSv (mGy cm)-1 for CT of the head, 0.62 x 10(-2) mSv (mGy cm)-1 for CT of the neck and 1.90 x 10(-2) mSv (mGy cm)-1 for CT of the trunk. CTDIw and DLP can be used for estimating the organ dose and effective dose associated with CT examinations of the head, neck and trunk.

Objectives Bone and soft-tissue calcifications are often coincidentally diagnosed on digital panoramic radiographs (DPRs). As the use of three-dimensional (3D) images has increased in the past decade for diagnostics in the mandibular region, we evaluated 3D volume images derived from 2D panoramic images to determine if this method is suitable for early detection of calcifications in this region. Methods In this study, three investigators retrospectively and independently evaluated 822 DPRs. If one or more calcifications were present, the 3D volume image from that patient was retrospectively evaluated to confirm the incidental findings. A radiographic system with a low-dose mode and a high-resolution 3D-image function was used. The investigators focussed on the most common calcifications, including tonsilloliths (TL), idiopathic osteosclerosis (IO) of the mandible, carotid artery calcifications (CAC), calcified submandibular lymph nodes (hereafter, CSL), and sialoliths of the submandibular salivary gland (SSG). Results One or more calcifications were identified in 415 (50.5%) DPRs. In total, 718 calcifications were detected, 30.2% of which were TL, 16.3% IO, 11.3% CAC, 8.8% CSL, and 1.7% SSG. Only 287 (39.97 %) of the calcifications were confirmed on 3D volume images; of these, 29.2% were TL, 58.5% IO, 0.2% CAC, and 1.4% SSG. No CSLs were detected. Conclusions Not all areas shown on the DPRs were visible in the retrospectively obtained 3D volume images. Whereas DPRs are used to diagnose calcifications such as IO, TL, SSG, CAC, and CSL, the 3D volume images were only useful for confirming the existence of IO, TL, and SSG calcifications.

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Sinus floor augmentation is an effective method to regain bone height for the successful insertion of dental implants into the posterior maxilla. The aim of the study was to evaluate the behaviour of augmentation material following simultaneous or staged dental implant insertion, as visible on digital panoramic radiographs using the GNU Image Manipulation Program (GIMP). We evaluated one-stage (group 1) or two-stage (group 2) maxillary sinus floor augmentation procedures in 19 patients, using a high temperature-treated bovine porous hydroxyapatite material. Digital panoramic radiographic measurements were captured pre-operatively in both groups, pre-implant insertion in group 2, and immediately postoperatively and 6 months postoperatively in both groups. Forty parallelwalled bone-level implants were placed in a one-stage (n=18) or two-stage (n=22) protocol, with a mean residual bone height of 4.9±1.8 mm and survival rate of 100%. Mean bone height increased by 8.6±1.6 mm immediately post-implantation and by 7.9±1.7 mm after 6 months. Mean distal and mesial bone losses after abutment connection were 0.42±0.24 mm and 0.34±0.27 mm, respectively. No significant intergroup or intragroup differences between simultaneous and staged dental implant procedures were found. Our results show that the histogram tool in GIMP is useful for documentation of the area of the augmentation material used in maxillary sinus floor augmentation.