• 치과방사선
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• 제27권2호
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• pp.105-116
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• 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.

• Imaging Science in Dentistry
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• 제40권1호
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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.

• 한국치위생학회지
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• 제17권5호
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• pp.721-733
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• 2017

Objectives: This study was conducted to help reduce the anxiety about dental radiation exposures of people and to provide a way to instill proper awareness of dental radiation. Methods: To fulfill the research aim, this study conducted a survey to 330 subjects who are 20 years old or over living in Seoul and Gyeonggi-do during the month of December 2016. The collected data were analyzed using frequency analysis, t-test, one-way ANOVA, Pearson's correlation coefficient and multiple regression analysis among others. Results: As a result of examining the correlation between the anxiety of dental radiography and the correlations between the variables showed that the knowledge of radiation knowledge and the need for radiography (r=0.186, p<0.01), thinking about shooting (r=0.137, p<0.05), and the effectiveness of wearing protective equipment (r=0.120, p<0.01), showing statistically significant differences. As a result of examining the factors influencing anxiety of dental radiography among adults, high awareness of the need for dental radiography (p<0.01), the more the idea of dental anxiety in dental radiography is radiography showed higher (p<0.01). Conclusions: It seems proper that adequate dental radiography requires adequate explanation about it to patients, wearing of protective equipment, and appropriate dental radiation safety education.

• 한국치위생학회지
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• 제18권6호
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• pp.1013-1023
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• 2018

Objectives: The purpose of this study is to evaluate dental hygiene students' recognition of safety management and phantom practice in dental radiology. Methods: The study subjects were 409 students in six regions who completed a dental radiology practice course and had on-job experience more than once. After understanding the study purpose and contents, they answered a questionnaire. The main jobs in dental radiology were analyzed. Results: As a result, regarding the most difficult aspects of dental radiology practice, "it is impossible to irradiate the mouth directly with X-rays" was the most common response (29.1%). Regarding the question "what is the main role of students in dental radiology practice?", the answer "it is shooting simulations using phantoms" accounted for 59.7% of responses. The most difficult regions in bisecting and paralleling radiography with a phantom were found to be the maxillary & mandibular molars and premolars. The most difficult technique was reported to be locating XCP maintenance to fit inside the mouth for both molars and premolars. The most difficult region to perform bitewing radiography using the phantom was the molar region (2.87), and the most difficult to perform occlusal radiography approaches were maxillary anterior general occlusal radiography (2.92) and mandibular cross-sectional occlusal radiography (3.00). Conclusions: The most technically difficult point in bitewing and occlusal radiography was the correct positioning of the vertical and horizontal angles. Radiography practice was considered to be more effective than previous mutual practice in terms of analysis of anatomical structures and patient treatment methods. Therefore, it will be necessary to improve policy regarding dental radiography practice at the department of dental hygienics and revise the necessary laws and regulations.

• Imaging Science in Dentistry
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• 제41권1호
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• pp.7-10
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• 2011

Purpose : The purpose of this study was to compare the conventional and digital radiography in the estimation of working length in mandibular molars. Materials and Methods : Sixty molar teeth were selected and divided into three groups in the basis of canal curves (0-$15^{\circ}$, 15-$30^{\circ}$, > $30^{\circ}$). After the placement of a 15 K-file, radiographs were taken with a conventional film (Fspeed) and a digital sensor. Canal lengths were measured in these images by two observers. Statistical analysis was performed with repeated measures of ANOVA and paired sample t-test with 95% confidence. Results : There was a high inter-observer agreement on the measurements of working length in conventional and digital radiographs. There was no significant difference between the mean values of measurements in conventional and digital radiography. Moreover, there was no significant difference between conventional and digital radiography with the actual values in the basis of canal curves. Conclusion : The accuracy of conventional and digital radiography in the determination of the working length was in an acceptable range.

• 대한방사선기술학회지:방사선기술과학
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• 제23권2호
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• pp.63-67
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• 2000

The purpose of this study is to survey the present status of portable radiography and the result of free space scattered dose rate when taking a radiography at the general hospital or the university hospital in Taejon city. The results were as follows; 1. The number of cases using portable radiography for three years increased to averages 16.2%, 7.7% per year from January 1st in 1996 to December 31st in 1998. 2. The average of distance of adjacent patients was 219.1 cm at the ward. 3. For portable chest radiography, the free space scattered dose rate was 10.5 mSv/hr at 50 cm distance, 1.8 mSv/hr at 100 cm distance, and 0.2 mSv/hr at 200 cm distance. Therefore, in case of portable chest radiography at the ward, the average of distance of adjacent patients is 219.1 cm, so it does not have influence on the adjacent patients. But during the portable radiography, a guardian who is close to the patient, doctor, nurse and radiologic technologists has to set up the shield to prevent from the unnecessary radiation or the distance should be as great as possible from the mobile X-ray equipment.

• 한국치위생학회지
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• 제14권4호
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• pp.527-537
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• 2014

Objectives : The purpose of this study was to investigate the influence of the awareness towards dental radiation exposure and concern in the adults. Methods : A self-reported questionnaires was filled out by 470 adults over 19 years old in Seoul from May 16 to July 10, 2013. Results : Fear for dental radiography showed that those who positively thought of radiography had 2.86 folds necessity of radiography than those who did not. Positive responders worried about the hazards of dental radiation 4.64 folds than the negative responders. More worried responders had felt the radiation hazards 1.83 folds than those who worried less. The worried responders also had higher awareness of dental radiation hazards. Conclusions : Frequent use of dental radiography is able to be prevented by protective devices. So it is important to prevent the possible hazards of the dental radiography by personal protective education.

• 대한디지털의료영상학회논문지
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• 제13권2호
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• pp.91-97
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• 2011

This study was conducted to know usefulness of panoramic radiography by comparing clinical evaluation and dental panoramic radiography in case of oral examination. Following results were concluded by analyzing difference between the result of Clinical evaluation and dental panoramic radiography. According to comparison the result of clinical evaluation and panoramic radiography, In Shin's research, dental caries was higher by 23.1%, periodontal disease was 31.9%, in An's research, dental caries was 24.2%. From new point of view from panoramic radiography, impacted tooth was 33.6%, Sinus abnormalities was 11.6%, periapical lesion was 5.4% in Shin's research and periapical lesion was 17.4%, 3rd molar impaction was 15.3% and retained root was 5.3% in An's research. Any kind of caries were not found in oral examination in the 66.7% of patients among patients with dental root caries in An's research. There were misdiagnose in oral examination(even side(59.5%),proximal side(59.5%), seconds caries(44.0%).

• 치과방사선
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• 제25권2호
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• pp.309-318
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• 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

• Nuclear Engineering and Technology
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• 제48권1호
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• pp.200-210
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• 2016

The neutron radiography reactor (NRAD) is a 250 kW Mark-II Training, Research, Isotopes, General Atomics (TRIGA) reactor at Idaho National Laboratory, Idaho Falls, ID, USA. The East Radiography Station (ERS) is one of two neutron beams at the NRAD used for neutron radiography, which sits beneath a large hot cell and is primarily used for neutron radiography of highly radioactive objects. Additional fuel elements were added to the NRAD core in 2013 to increase the excess reactivity of the reactor, and may have changed some characteristics of the neutron beamline. This report discusses characterization of the neutron beamline following the addition of fuel to the NRAD. This work includes determination of the facility category according to the American Society for Testing and Materials (ASTM) standards, and also uses an array of gold foils to determine the neutron beam flux and evaluate the neutron beam profile. The NRAD ERS neutron beam is a Category I neutron radiography facility, the highest possible quality level according to the ASTM. Gold foil activation experiments show that the average neutron flux with length-to-diameter ratio (L/D) = 125 is $5.96{\times}10^6n/cm^2/s$ with a $2{\sigma}$ standard error of $2.90{\times}10^5n/cm^2/s$. The neutron beam profile can be considered flat for qualitative neutron radiographic evaluation purposes. However, the neutron beam profile should be taken into account for quantitative evaluation.