• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.25 no.2
• /
• pp.309-318
• /
• 1995

In head and neck region, the critical organ and tissue doses were determined, and the risks were estimated from lateral, posteroanterial and basilar cephalometric radiography. For each cephalometric radiography, 31 TLDs were placed in selected sites(18 internal and 13 external sites) in a tissue-equivalent phantom and exposed, then read-out in the TLD reader. The results were as follows: 1. From lateral cephalometric radiography, the highest effective dose recorded was that delivered to the salivary gland(3.6pSv) and the next highest dose was that received by the bone marrow(3pSv). 2. From posteroanterial cephalometric radiography, the highest effective dose recorded was that delivered to the salivary gland(2pSv) and the next highest dose was that received by the bone marrow(1.8pSv). 3. From basilar cephalometric radiography, the highest effective dose recorded was that delivered to the thyroid gland(31A p Sv) and the next highest dose was that received by the salivary gland(13.3 p Sv). 4. The probabilities of stochastic effect from lateral, posteroanterial and basilar cephalometric radiography were $0.72{\times}10^{-6}$, $0.49{\times}10^{-6}$ and $3.51{\times}10^{-6}$, respectively

• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.27 no.2
• /
• pp.105-116
• /
• 1997

The purpose of this study is to evaluate the cephalometric reproducibility in digitized cephalometric radiography by comparing the measurement errors between the remeasured and retaken conventional and digitized lateral cephalometric radiography. The mean of the differences and error percentage of each cephalometric measurement were obtained using 96 lateral cephalometric radiography from 48 patients between the age of 11 and 13. The results were as follows; 1. The repeated measurement group of conventional radiography showed least amount of mean differences while those of the retaken measurement group of digitized image showed largest amount of mean differences in every measurement. 2. The measurements which showed statistically significant difference between the conventional radiography and digitized image were S-Go, Ar-Go, S-Ar-Go and S-sN-sNT in repeated measurement group. 3. The measurements which showed statistically significant difference between the repeated and retaken measurement groups were N-S-Ar, MP-Ll and S-sN-sPog in conventional radiography and S-N, Go-Me and N-A in digitized Image. 4. Large amount of error percentage was shown at A-N-B and N-A in retaken measurement group of conventional radiography and N-S-Ba and A-N-B in retaken measurement group of digitized image. 5. The amount of error percentage at Ar-Go and N-S- Ar in retaken measurement group of conventional radiography and S-N, N-A, S-N-B and N-S-Ba in retaken measurement group of digitized image was more than double than those from remeasured groups.

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

• The korean journal of orthodontics
• /
• v.32 no.2 s.91
• /
• pp.79-89
• /
• 2002

The purpose of this study is to evaluate the reproducibility and errors in landmark identification of conventional lateral cephalometric radiography and digital lateral cephalometric radiography. Fifteen conventional lateral cephalometric radiographs and fifteen digital lateral cephalometric radiographs were selected in adults with no considerations on sex and craniofacial forms. Each landmark was identified and expressed as the coordinate (x, y). The landmarks were classified into 3 groups. The landmarks of the first identification was T1, identification after one week was T2, and identification after one month was T3. The mean and standard deviation of identification errors between replicates were calculated according to the x and y coordinates. The errors between first identification and second identification were expressed as T2-T1(x), T2-T1(y) and those between first identification and third identification were expressed as T3-T1(x), T2-T1(y). Each was divided into conventional lateral cephalometric radiography and digital lateral cephalometric radiography. The independent t- test was used for statistical analysis of identification errors for the evaluation of reproducibility. The results of this study were as follows ; 1. Generally, the mean and standard deviation of landmark identification errors in digital lateral cephalometric radiography was smaller than those of conventional lateral cephalometric radiography. 2. Only a few landmarks showed statistically significant difference in identification error between conventional lateral cephalometric radiography and digital lateral cephalometric radiography. 3. The enhancement of image quality didn't guarantee decrease in landmark identification error and didn't affect tendency of landmark identification error.

• Imaging Science in Dentistry
• /
• v.40 no.4
• /
• pp.165-169
• /
• 2010

Purpose : To survey the radiographic examination protocol for lateral cephalometric radiographic examinations and to measure their patient doses in Korea and to compare the dose according to the size of hospital, the type of image receptor system, and the installation duration. Materials and Methods : The radiographic examination protocols (kVp, mA, and exposure time) for lateral cephalometric radiography were surveyed with 61 cephalometric radiographic equipments and their patient dose-area product (DAP) measured with a DAP meter (DIAMENTOR M4-KDK, PTW, Freiburg, Germany) for 51 cephalometric radiographic equipments. The radiographic examination protocols and patient doses were compared according to the size of hospital (university dental hospital, dental hospital, and dental clinic), the type of image receptor system (film-based, DR and CR type) and the installation duration, respectively. SPSS 12.0.1 for Windows (SPSS Inc., Chicago, USA) was used for independent t-test and ANOVA test. Results : The average protocols were 77.0 kVp, 12.7 mA, 6.2 second for cephalometric radiography. The average patient dose (DAP) was $128.0mGy\;cm^2$ and 3rd quartile dose (DAP) $161.1mGy\;cm^2$ for cephalometric radiography for adult male. There was no statistically significant difference at average patient DAP according to the size of hospital, the type of image receptor system, and the installation duration, repectively. Conclusion : The average patient dose was $128.0mGy\;cm^2$ and the third quartile patient dose $161.1mGy\;cm^2$ for lateral cephalometric radiography for adult male in Korea.

• Journal of dental hygiene science
• /
• v.22 no.2
• /
• pp.75-82
• /
• 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
• /
• v.32 no.4
• /
• pp.213-219
• /
• 2002

Purpose : Computed radiography (CR) has been used in cephalometric radiography and many studies have been carried out to improve image quality using various digital enhancement and filtering techniques, During CR image acquisition, the frequency rank and type affect to the image quality. The aim of this study was to compare the diagnostic quality of conventional cephalometric radiographs to those of computed radiography. Materials and Methods : The diagnostic quality of conventional cephalometric radiographs (MO) and their digital image counterparts were compared, and at the same time, six modalities (M1-M6) of spatial frequency-processed digital images were compared by evaluating the reproducibility of 23 cephalometric landmark locations. Reproducibility was defined as an observer's deviation (in mm) from the mean between all observers. Results and Conclusion: In comparison with the conventional cephalometric radiograph (MO), Ml showed statistically significant differences in 8 locations, M2 in 9, M3 12, M4 in 7, M5 in 12, and M6 showed significant differences in 14 of 23 landmark locations (p < 0.05). The number of reproducible landmarks that each modality possesses were 7 in M6, 6 in M5, 5 in M3, 4 in M4, 3 in M2, 2 in Ml, and 1 location in MO. The image modality that observers selected as having the best image quality was M5.

• Journal of the Korean Society of Radiology
• /
• v.10 no.5
• /
• pp.291-298
• /
• 2016

Recently, the interest in the orthodontic treatment for children is increased by a rise in national income level. The number of cephalometric radiography that could diagnose a malocclusion and malposition between teeth and jawbone increased. It required attention to radiation exposure, because the subject of dental examination is children which are more sensitive to radiation and the head and neck, the object of that include radiation sensitive organ such as the thyroid, bone marrow, eyes, salivary gland, and so on. In this study, we measured two-dimensional dose distribution in cephalometric radiography system (VATEC Pax-400C) using Agfa CP-G Plus film and MagicMax Dosimeter, and calculated radiation organ dose of head and neck through MCNPX simulation. And then we designed a radiation protective device to decrease radiation dose. The dose distribution of the cephalometric radiography system irradiated the head and neck overall as well as the oral and maxillofacial parts. The radiation organ dose calculated that thyroid, oesophagus and eyes are irradiated high, and the radiation organ dose decreased about 70 ~ 80% by the application of the radiation protective device. The results of this study will be used construction of database for dental radiation exposure and research of reducing radiation dose.

• 대한치과교정학회:학술대회논문집
• /
• 2005.11a
• /
• pp.68.1-68.1
• /
• 2005

• Imaging Science in Dentistry
• /
• v.45 no.3
• /
• pp.175-180
• /
• 2015

Purpose: This study was performed to evaluate the reliability of the identification of anatomical landmarks in panoramic and lateral cephalometric radiographs on a standard medical grade picture archiving communication system (PACS) monitor and a tablet computer (iPad 5). Materials and Methods: A total of 1000 radiographs, including 500 panoramic and 500 lateral cephalometric radiographs, were retrieved from the de-identified dataset of the archive of the Section of Oral and Maxillofacial Radiology of the University Of Connecticut School Of Dental Medicine. Major radiographic anatomical landmarks were independently reviewed by two examiners on both displays. The examiners initially reviewed ten panoramic and ten lateral cephalometric radiographs using each imaging system, in order to verify interoperator agreement in landmark identification. The images were scored on a four-point scale reflecting the diagnostic image quality and exposure level of the images. Results: Statistical analysis showed no significant difference between the two displays regarding the visibility and clarity of the landmarks in either the panoramic or cephalometric radiographs. Conclusion: Tablet computers can reliably show anatomical landmarks in panoramic and lateral cephalometric radiographs.