• The Journal of the Korean dental association
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• v.57 no.1
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• pp.26-33
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• 2018

Panoramic radiography is widely used as a primary radiological diagnosis in dentistry. However, due to the overlapping of anatomical structures, diagnostic capability of panoramic radiography is limited. Recently, panoramic machine equipped with various image processing software has been introduced to improve the diagnostic capability. This study aims to introduce panoramic equipment with multi-layer imaging software that can provide 41 images from anterior to posterior in region of interest, and to report in various clinical applications.

• The Journal of the Korean dental association
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• v.53 no.8
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• pp.558-568
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• 2015

Objective: The objectives of this study were to measure pediatric organ and effective doses of cone-beam computed tomography (CBCT) for orthodontic analysis and to compare them to those of panoramic and lateral cephalometric radiography, the conventional radiography for orthodontic analysis. Materials and Methods: Alphard VEGA for CBCT, Planmeca Proline XC for panoramic radiography and Orthophos CD for cephalometric radiography were used for this study. Thermoluminescent dosimeter (TLD) chips were located at 24 anatomic sites of 10-year-old anthropomorphic phantom and exposed during CBCT (C-mode; $200{\times}179mm$ FOV), panoramic and lateral cephalometric radiographic procedures at the clinical exposure settings for 10-year-old patient. Pediatric organ and effective doses were measured and calculated using ICRP 2007 tissue weighting factors. Results: Effective doses of CBCT, panoramic radiography and lateral cephlometric radiography in pediatric clinical exposure settings were $292.5{\mu}Sv$, $19.3{\mu}Sv$, and $4.4{\mu}Sv$ respectively. The thyroid gland contributed most significantly to the effective dose in all the radiographic procedures. Conclusion: Effective dose of CBCT was about 12 times to conventional radiographic procedures for orthodontic analysis in pediatric patient. The use of CBCT for orthodontic analysis should be fully justified over conventional radiography and dose optimization to decrease thyroid dose is needed in pediatric patients.

• Imaging Science in Dentistry
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• v.37 no.2
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• pp.87-92
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• 2007

Purpose: To measure the absorbed doses of cone beam computed tomography (CBCT), which is recently being more frequently used, and to compare them with those of panoramic radiography. Materials and Methods: To measure the absorbed doses of CBCT ($PSR-9000N^{TM}$, Asahi Roentgen Ind. Co., Japan), we placed TLD chips on the skin regions above the parotid and thyroid glands, and on the dorsum of tongue in a dental head phantom. We used two image acquisition modes of the Dental and Panoramic modes of CBCT, which differed in the field of view. Also, panoramic radiographs (Auto IIIN, Asahi Roentgen Ind. Co., Japan) were taken to compare with the absorbed doses of CBCT. Result: In the Dental mode of CBCT, the absorbed doses of the parotid gland, dorsum of tongue, and thyroid gland were 3.53, 3.13, and 0.36 mGy, respectively. In the Panoramic mode of CBCT, they were 9.57, 9.15, and 0.85 mGy, respectively. The panoramic mode showed higher absorbed doses than those of the Dental mode. In the panoramic radiography, the absorbed doses of the parotid gland, dorsum of tongue, and thyroid gland were 1.21, 1.19, and 0.16 mGy, respectively. And they were about 1/3 of the Dental mode and 1/9 of the Panoramic mode of CBCT. Conclusion: Absorbed doses of CBCT are higher than those of panoramic radiography, and dependent upon the field of view.

• Journal of dental hygiene science
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• v.22 no.2
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• pp.75-82
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• 2022

Background: Dental hygienists study dental radiology through the dental hygiene department and curriculum, and most of the radiography work in dental clinics is performed by dental hygienists; however, the legal work regulations for dental hygienists place restrictions on the type of radiography performed. This study aimed to identify the actual conditions of the radiographic work performed by dental hygienists and to determine the difference according to the type of hospital. Methods: This study included 195 dental hygienists working at dental medical institutions in the metropolitan area. A survey was conducted on regarding the radiographic work performed and the clinical career of the main performers. The radiography work was divided into periapical radiography, bite-wing radiography, occlusal radiography, panoramic radiography, computed tomography (CT), and cephalometric radiography. Results: The frequency of performing intraoral radiography was as follows: periapical radiography, 94.9%; bite-wing radiography, 93.8%; and occlusal radiography, 77.9%. The frequency of performing extraoral radiography was 94.4% for panoramic radiography, 89.7% for CT, and 73.3% for cephalometric radiography. The frequency of internal and external radiography performance was higher among hygienists in dental clinics than among those in dental hospitals and university hospitals. The analysis of the dental hygienists' clinical experience in the areas of intraoral and extraoral radiography showed that those working at university hospitals, dental hospitals, and dental clinics had over 5 years, 2~4 years, and 1 year of clinical experience, respectively. The hygienists with less than 1 year of clinical experience showed high performance frequency (p<0.05). Conclusion: For the dental hygienists to perform radiography safely, a discussion regarding the revision of related laws and regulations is warranted.

• Imaging Science in Dentistry
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• v.38 no.4
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• pp.209-213
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• 2008

Purpose : To evaluate the relative diagnostic accuracy of panoramic radiography and Water's projection in maxillary sinus inflammatory diseases by comparing the radiodensities of the images with those of CT. Materials and Methods : Panoramic radiographs, Waters' projection, and CT images from 55 subjects (11O sinuses) were included in this retrospective study. The radiodensity of each maxillary sinus in panoramic radiography was recorded separately as upper and lower divided horizontally by hard palate. In Waters' projection, the overall sinus radiodensity was recorded. The CT images were considered as gold standard. Results : In panoramic radiography, 83 sinuses had same upper and lower radiodensity and 72 of these were consistent with those of CT, 26 sinuses had different upper and lower radiodensity and 15 of these, upper radiodensity was consistent with CT, the remaining 11, lower radiodensity was consistent with CT. One sinus had upper radiolucency with lower radiopacity and both were consistent with those of CT. Altogether 73 (66.4%) among 110 sinuses in panoramic radiography showed full agreement with CT, 26 (23.6%) showed partial agreement with CT. 9 sinuses had no lower image under the hard palate in panoramic radiography due to the smaller size of sinus. In Waters' projection, the radiodensity of 105 sinuses (95.5%) were consistent with that of CT. Conclusion : The panoramic radiography showed 90.0% of the sinus conditions fully or partially which may appear less accurate than that of Water's view (95.5%) but with more detailed information of the inferior part of sinuses. (Korean J Oral Maxillofac Radiol 2008; 38 : 209-13)

• Imaging Science in Dentistry
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• v.45 no.2
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• pp.117-122
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• 2015

Purpose: Panoramic radiographs taken using conventional chin-support devices have often presented problems with positioning accuracy and reproducibility. The aim of this report was to propose a new bite block for panoramic radiographs of anterior edentulous patients that better addresses these two issues. Materials and Methods: A new panoramic radiography bite block similar to the bite block for dentulous patients was developed to enable proper positioning stability for edentulous patients. The new bite block was designed and implemented in light of previous studies. The height of the new bite block was 18 mm and to compensate for the horizontal edentulous space, its horizontal width was 7 mm. The panoramic radiographs using the new bite block were compared with those using the conventional chin-support device. Results: Panoramic radiographs taken with the new bite block showed better stability and bilateral symmetry than those taken with the conventional chin-support device. Patients also showed less movement and more stable positioning during panoramic radiography with the new bite block. Conclusion: Conventional errors in panoramic radiographs of edentulous patients could be caused by unreliability of the chin-support device. The newly proposed bite block for panoramic radiographs of edentulous patients showed better reliability. Further study is required to evaluate the image quality and reproducibility of images with the new bite block.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.28 no.1
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• pp.7-16
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• 1998

The Scanora/sup (R)/ X-ray unit uses the principles of narrow beam radiography and spiral tomography. Starting with a panoramic overview as a scout image. multiple tomographic projections could be selected. This study evaluated the accuracy of spiral tomography in comparison to routine panoramic radiography for dental implant treatment planning. An experimental study was performed on a cadaver mandible to assess the accuracy of panoramic radiography and spiral tomography film images for measurement of metallic spheres. After radiographic images of the metallic spheres on the surgical stent were measured and corrected for a fixed magnification of radiographic images. following results were obtained. 1. In the optimal position of the mandible. the minimal horizontal and vertical distortion was evident in the panoramic radiography images. The mean horizontal and vertical magnification error in anterior sites was 5.25％ and 0.75％. respectively. The mean horizontal and vertical magnification error in posterior sites was 0.50％ and 1.50％. respectively. 2. In the displaced forward or in an eccentric position of the mandible. the magnification error of the panoramic radiography images increased significantly over the optimal position. Overall, the mean horizontal magnification error of the anterior site in the different positions changed dramatically within a range of -17.25％ to 39.00％, compared to the posterior range of -5.25％ to 8.50％. However, the mean vertical magnification error stayed with the range of 0.5％ to 3.75％ for all the mandibular positions. 3. The magnification effects in the tomographic scans were nearly identical for the anterior and posterior with a range of 2.00％ to 5.75％ in the horizontal and 4.50％ to 5.50％ in the vertical dimension, respectively. 4. A statistically significant difference between the anterior and posterior measurements was found in the horizontal measurements of the panoramic radiography images of the displaced forward and backward position of the mandible(P<0.05). Also a significant difference between the optimal panoramic and tomographic projections was found only in the vertical measurement(P<0.05).

• Imaging Science in Dentistry
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• v.40 no.1
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• pp.9-14
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• 2010

Purpose : We evaluated the absorbed doses to the organs and calculated the effective doses when using the digital panoramic radiography. Materials and Methods : The absorbed dose averages in major organs of oral and maxillofacial region were measured using the Dental head phantom (CIRS Co., USA), $^nLi_2B_4O_7$ TLD chip and UD-716AGL dosimeter (Matsushita Electric Industrial Co., JPN) when performing indirect and direct digital panoramic radiography. Effective doses were calculated from correspond to ICRP 2007 recommendations for two panoramic radiography. Results : The absorbed dose average on indirect and direct digital panoramic radiography was highest in parotid glands as measured 1259.6 mGy and 680.7 mGy respectively. Absorbed dose average in another organs were high in order of esophagus, submandibular gland, tongue and thyroid gland on both types of digital panoramic radiography. The absorbed dose average was higher on indirect type than direct one (p<0.05). The effective dose was higher on indirect type than direct one as measured 13.28 mSv and 8.70 mSv respectively. Conclusion : The absorbed doses in salivary gland and oral mucosa were high. However, thyroid gland also demands the attention on radiography due to high tissue weighting factor in spite of the low absorbed dose.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.29 no.1
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• pp.223-239
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• 1999

Purpose: to evaluate the usefulness of the panoramic radiography, generally used in dental clinic, for the detection of the maxillary sinus pathosis due to the inflammation and tumor, through the comparison with CT findings as the absolute standard. Materials & Methods: 150 maxillary sinuses of 75 patients with or without particular signs and symptoms and showing soft tissue lesions or destruction of maxillary sinus walls in at least one sinus in CT, were selected as subject samples, and the panoramic radiography of the same patients were interpretated by 3 dental radiologists and 3 non dental radiologist given no previous informations. Using the CT findings as the absolute standard, the diagnostic ability of panoraimc radiography in the mucosal thickening, maxillary sinus haziness, inferior wall destruction, medial wall destruction, posterolateral wall destruction and the superior wall destruction was evaluated using the ROC curve and the difference between dental radiologist group and non dental radiologist group was also evaluated. Results: 1. When dental radiologist group interpretated the destruction of inferior wall and posterolateral wall, the kappa value which shows interobserver's coincidence was above 0.75. 2. The diagnostic ability according to site of interpretation was the highest when the inferior wall was interpretated in both observer groups and there was a statistically significant difference between the dental radiologist group and non dental radiologist group in interpretating the mucosal thickening, haziness, destruction of the inferior and medial wall(p<0.05). 3. The diagnostic ability in detecting the destruction of the sinus walls was better than in soft tissue lesions in both groups and between the groups there was a statistically significant difference(p<0.05). Conclusion: When detecting the destruction of inferior and posterolateral wall of the maxillary sinus there was coincident with that of CT findings, and so it is considered that diagnostic ability of panoramic radiography is high in this point. But in interpretating the destruction of medial wall and soft tissue lesions, diagnostic ability of the panoramic radiography was relatively low and there was a significant difference between the dental radiologist group and non dental radiologist group. Therefore CT or other auxiliary diagnostic method will be necessary when evaluating thorough pathosis of maxillary sinus objectively.

• Imaging Science in Dentistry
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• v.35 no.4
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• pp.199-202
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• 2005

Purpose : To report the incidence of radiological findings from screening panoramic radiographs and verify the validity of the panoramic radiography for screening purposes. Materials and Methods : Six thousand one hundred and sixty panoramic radiographs taken from the patients visiting the Health Promotion Center of CNUH were selected for this retrospective study. Panoramic radiographs were examined into the following pathologic conditions : the presence of periodontal bone loss, dental caries, periapical radiolucencies, retained roots, impacted supernumerary teeth, impacted third molars, odontoma, cystic lesions other than radicular cyst, sialoliths, and mixed radiolucent-radiopaque lesions. Number of pathologic conditions and Prevalence values were recorded. Results: The prevalences of pathologic conditions were $72.9\%$ of periodontal bone loss, $32.2\%$ of dental caries, $11.9\%$ of periapical radiolucencies, $10.8\%$ of retained roots, $0.4\%$ of root fracture, $1.0\%$ of impacted supernumerary teeth, $1.0\%$ of impacted third molars, $0.06\%$ of odontoma, $0.08\%$ of cystic lesion other than radicular cyst, $0.2\%$ of prolonged retention of deciduous tooth, $0.1\%$ of sialolith, and $0.04\%$ of mixed radiopaque and radiolucent lesion. Conclusion : Although the panoramic radiograph should not be used to replace intraoral radiographic and clinical examinations, this study showed that many dental pathologic conditions could be detected on panoramic radiographs. The panoramic radiograph might serve as a diagnostic aid in dental health evaluation programs.