The current study investigates the feasibility of a platform for a nationwide dose monitoring system for dental radiography. The essential elements for an unerring system are also assessed.An intraoral radiographic machine with 14 X-ray generators and five sensors, 45 panoramic radiographic machines, and 23 cone-beam computed tomography (CBCT) models used in Korean dental clinics were surveyed to investigate the type of dose report. A main server for storing the dose data from each radiographic machine was prepared. The dose report transfer pathways from the radiographic machine to the main sever were constructed. An effective dose calculation method was created based on the machine specifications and the exposure parameters of three intraoral radiographic machines, five panoramic radiographic machines, and four CBCTs. A viewing system was developed for both dentists and patients to view the calculated effective dose. Each procedure and the main server were integrated into one system.The dose data from each type of radiographic machine was successfully transferred to the main server and converted into an effective dose. The effective dose stored in the main server is automatically connected to a viewing program for dentist and patient access.A patient radiation dose monitoring system is feasible for dental clinics. Future research in cooperation with clinicians, industry, and radiologists is needed to ensure format convertibility for an efficient dose monitoring system to monitor unexpected radiation dose.
Purpose:The aim of this study was to determine whether the panoramic mandibular index (PMI) is useful for assessing bone mineral density.We also analyzed the potential correlations between PMI parameters and patient age.Materials and Methods: Four observers measured the PMI of both sides of the mental foramen using a picture archiving and communication system and images in the Digital Imaging and Communications in Medicine format.They studied 300 panoramic radiographic images of patients belonging to the following age groups: 4049 years, 5059 years, 6069 years, 7079 years, and 8089 years.The observers were allowed to zoom in or out and to adjust the contrast of the images.Further, they were instructed to record the reasons for any measurements that could not be made.Then, we conducted a reliability analysis of the measured PMI and assessed the correlations between different patient age groups and the 3 parameters used for determining the PMI from the available data.Results: Among the 600 data items collected, 23 items were considered unmeasurable by at least 1 observer for the following 4 reasons: postoperative state, lesion, unidentified mental foramen, and alveolar bone loss.The intra observer reproducibility of the measurable data was 0.6110.752.The mandibular cortical width (MCW) decreased significantly as patient age increased.Conclusion: PMI had limited usability when the margin of the mental foramen was not clear.In contrast, MCW, a parameter used for determining the PMI, had fewer drawbacks than the PMI with respect to bone mineral density measurements and exhibited a significant correlation with patient age.(
An individual surgical stent fabricated from computed tomography (CT) data, called a CT-guided stent, would be useful for accurate installation of implants. The purpose of the present study was to introduce a newly developed CT-guided stent with a simple design and evaluate the accuracy of the stent placement.A resin template was fabricated from a hog mandible and a specially designed plastic plate, with 4 metal balls inserted in it for radiographic recognition, was attached to the occlusal surface of the template. With the surgical stent applied, CT images were taken, and virtual implants were placed using software. The spatial positions of the virtually positioned implants were acquired and implant guiding holes were drilled into the surgical stent using a specially designed 5-axis drilling machine. The surgical stent was placed on the mandible and CT images were taken again. The discrepancy between the central axis of the drilled holes on the second CT images and the virtually installed implants on the first CT images was evaluated.The deviation of the entry point and angulation of the central axis in the reference plane were 0.47±0.27 mm, 0.57±0.23 mm, and 0.64±0.16°, 0.57±0.15°, respectively. However, for the two different angulations in each group, the 20° angulation showed a greater error in the deviation of the entry point than did the 10° angulation.The CT-guided template proposed in this study was highly accurate. It could replace existing implant guide systems to reduce costs and effort.
Purpose:The aim of this study was to provide sex-matched three-dimensional (3D) statistical shape models of the mandible, which would provide cephalometric parameters for 3D treatment planning and cephalometric measurements in orthognathic surgery. Materials and Methods:The subjects used to create the 3D shape models of the mandible included 23 males and 23 females.The mandibles were segmented semi-automatically from 3D facial CT images.Each individual mandible shape was reconstructed as a 3D surface model, which was parameterized to establish correspondence between different individual surfaces.The principal component analysis (PCA) applied to all mandible shapes produced a mean model and characteristic models of variation.The cephalometric parameters were measured directly from the mean models to evaluate the 3D shape models.The means of the measured parameters were compared with those from other conventional studies.The male and female 3D statistical mean models were developed from 23 individual mandibles, respectively.Results: The male and female characteristic shapes of variation produced by PCA showed a large variability included in the individual mandibles.The cephalometric measurements from the developed models were very close to those from some conventional studies. Conclusion:We described the construction of 3D mandibular shape models and presented the application of the 3D mandibular template in cephalometric measurements.Optimal reference models determined from variations produced by PCA could be used for craniofacial patients with various types of skeletal shape.(
The purpose of this study was to investigate the level of clinical image quality of panoramic radiographs and to analyze the parameters that influence the overall image quality.Korean dental clinics were asked to provide three randomly selected panoramic radiographs. An oral and maxillofacial radiology specialist evaluated those images using our self-developed Clinical Image Quality Evaluation Chart. Three evaluators classified the overall image quality of the panoramic radiographs and evaluated the causes of imaging errors.A total of 297 panoramic radiographs were collected from 99 dental hospitals and clinics. The mean of the scores according to the Clinical Image Quality Evaluation Chart was 79.9. In the classification of the overall image quality, 17 images were deemed 'optimal for obtaining diagnostic information,' 153 were 'adequate for diagnosis,' 109 were 'poor but diagnosable,' and nine were 'unrecognizable and too poor for diagnosis'. The results of the analysis of the causes of the errors in all the images are as follows: 139 errors in the positioning, 135 in the processing, 50 from the radiographic unit, and 13 due to anatomic abnormality.Panoramic radiographs taken at local dental clinics generally have a normal or higher-level image quality. Principal factors affecting image quality were positioning of the patient and image density, sharpness, and contrast. Therefore, when images are taken, the patient position should be adjusted with great care. Also, standardizing objective criteria of image density, sharpness, and contrast is required to evaluate image quality effectively.
Purpose:The purpose of this study was to investigate appropriate contrast reference values (CRVs) by comparing the contrast in phantom and clinical images.Materials and Methods: Phantom contrast was measured using two methods: (1) counting the number of visible pits of different depths in an aluminum plate, and (2) obtaining the contrast-to-noise ratio (CNR) for 5 tissue-equivalent materials (porcelain, aluminum, polytetrafluoroethylene [PTFE], polyoxymethylene [POM], and polymethylmethacrylate [PMMA]).Four panoramic radiographs of the contrast phantom, embedded in the 4 different regions of the arch-form stand, and 1 real skull phantom image were obtained, post-processed, and compared.The clinical image quality evaluation chart was used to obtain the cut-off values of the phantom CRV corresponding to the criterion of being adequate for diagnosis.results: The CRVs were obtained using 4 aluminum pits in the incisor and premolar region, 5 aluminum pits in the molar region, and 2 aluminum pits in the temporomandibular joint (TMJ) region.The CRVs obtained based on the CNR measured in the anterior region were: porcelain, 13.95; aluminum, 9.68; PTFE, 6.71; and POM, 1.79.The corresponding values in the premolar region were: porcelain, 14.22; aluminum, 8.82; PTFE, 5.95; and POM, 2.30.In the molar region, the following values were obtained: porcelain, 7.40; aluminum, 3.68; PTFE, 1.27; and POM, -0.18.The CRVs for the TMJ region were: porcelain, 3.60; aluminum, 2.04; PTFE, 0.48; and POM, -0.43.Conclusion: CRVs were determined for each part of the jaw using the CNR value and the number of pits observed in phantom images.
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