• Journal of the Korean Society of Radiology
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• v.11 no.1
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• pp.55-61
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• 2017

There are no recommended test conditions for digital photography in Chest PA examinations. However, each company recommends shooting examinations of the high voltage applied to the previous analog examination. The condition that satisfies the value of 200 ~ 800 which is the recommended Exposure Index value recommended by Philips was selected, and the dose was evaluated by Monte Carlo simulation, and the SNR and CNR were compared. As a result, it was possible to reduce the effective dose up to 77% by controlling the tube voltage, tube current, and additional filter, not the conventional high voltage imaging method. Although there were some differences according to the test conditions, the image evaluation results were similar to the images. We will compare the exposure dose according to changes in tube voltage, tube current, and additional filter at the digital chest radiograph and evaluate the image quality of the image to propose optimal conditions.

• Imaging Science in Dentistry
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• v.41 no.4
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• pp.151-153
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• 2011

Purpose : The purpose of this study was to obtain the description of the mandibular bone quality of male and female patients between 40-60 years old and their differences based on mandibular cortical bone thickness measured using Mental Index (MI). Materials and Methods : Forty digital panoramic radiographs, which consisted of twenty male and twenty female patients, 40-60 years old, were observed. Mandibular cortical bone thickness was measured using MI on both sides of the mandible. The average MI score of two groups were then assessed using t-sample independent test. Results : There were significant differences of mandibular bone quality based on mandibular cortical bone thickness measurement using MI between male and female patients (p<0.05). Conclusion : Mandibular bone quality based on cortical bone thickness measurement using MI of male and female patients indicated a significant difference.

• Imaging Science in Dentistry
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• v.43 no.3
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• pp.145-151
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• 2013

Purpose: This study was performed to evaluate and compare the radiopacity of dentin, enamel, and 8 restorative composites on conventional radiograph and digital images with different resolutions. Materials and Methods: Specimens were fabricated from 8 materials and human molars were longitudinally sectioned 1.0 mm thick to include both enamel and dentin. The specimens and tooth sections were imaged by conventional radiograph using #4 sized intraoral film and digital images were taken in high speed and high resolution modes using a phosphor storage plate. Densitometric evaluation of the enamel, dentin, restorative materials, a lead sheet, and an aluminum step wedge was performed on the radiographic images. For the evaluation, the Al equivalent (mm) for each material was calculated. The data were analyzed using one-way ANOVA and Tukey's test (p<0.05), considering the material factor and then the radiographic method factor, individually. Results: The high speed mode allowed the highest radiopacity, while the high resolution mode generated the lowest values. Furthermore, the high resolution mode was the most efficient method for radiographic differentiation between restorative composites and dentin. The conventional radiograph was the most effective in enabling differentiation between enamel and composites. The high speed mode was the least effective in enabling radiographic differentiation between the dental tissues and restorative composites. Conclusion: The high speed mode of digital imaging was not effective for differentiation between enamel and composites. This made it less effective than the high resolution mode and conventional radiographs. All of the composites evaluated showed radiopacity values that fit the ISO 4049 recommendations.

• Imaging Science in Dentistry
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• v.46 no.3
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• pp.179-184
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• 2016

Purpose: In the present study, we coined the term 'alveolar dome' and aimed to demonstrate the prevalence of alveolar domes through digital periapical radiographs. Materials and Methods: This study examined 800 digital periapical radiographs in regard to the presence of alveolar domes. The periapical radiographs were acquired by a digital system using a photostimulable phosphor (PSP) plate. The ${\chi}^2$ test, with a significance level of 5%, was used to compare the prevalence of alveolar domes in the maxillary posterior teeth and, considering the same teeth, to verify the difference in the prevalence of dome-shaped phenomena between the roots. Results: The prevalence of alveolar domes present in the first pre-molars was statistically lower as compared to the other maxillary posterior teeth (p<0.05). No statistically significant difference was observed in the prevalence of alveolar domes between the maxillary first and second molars. Considering the maxillary first and second molars, it was observed that the palatal root presented a lower prevalence of alveolar domes when compared to the distobuccal and mesiobuccal roots (p<0.05). Conclusion: The present study coined the term 'alveolar dome', referring to the anatomical projection of the root into the floor of the maxillary sinus. The maxillary first and second molars presented a greater prevalence of alveolar domes, especially in the buccal roots, followed by the third molars and second pre-molars. Although the periapical radiograph is a two-dimensional method, it can provide dentists with the auxiliary information necessary to identify alveolar domes, thus improving diagnosis, planning, and treatment.

• Journal of radiological science and technology
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• v.34 no.1
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• pp.9-15
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• 2011

In this paper, an image quality evaluation of amorphous selenium based x-ray system was performed using modulation transfer function (MTF) measurement. MTF as a main factor of imaging quality evaluation was investigated by contrast method from acquired test pattern image. The MTF value was measured to 36.1% at 3.0 lp/mm which is twice as high as that in the film image. Compared with other studies, the results demonstrate that amorphous selenium based x-ray detector is clinically meaningful.

• Imaging Science in Dentistry
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• v.51 no.2
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• pp.137-148
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• 2021

Purpose: This study aimed to assess the computer monitors used for analysis and interpretation of digital radiographs within the clinics of the Oral Health Centre of Western Australia. Materials and Methods: In total, 135 computer monitors(3 brands, 6 models) were assessed by analysing the same radiographic image of a combined 13-step aluminium step wedge and the Artinis CDDent 1.0^® (Artinis Medical Systems B.V.^®, Elst, the Netherlands) test object. The number of steps and cylindrical objects observed on each monitor was recorded along with the monitor's make, model, position relative to the researcher's eye level, and proximity to the nearest window. The number of window panels blocked by blinds, the outside weather conditions, and the number of ceiling lights over the surgical suite/cubicle were also recorded. MedCalc^® version 19.2.1 (MedCalc Software Ltd^®, Ostend, Belgium, https://www.medcalc.org; 2020) was used for statistical analyses(Kruskal-Wallis test and stepwise regression analysis). The level of significance was set at P<0.05. Results: Stepwise regression analysis showed that only the monitor brand and proximity of the monitor to a window had a significant impact on the monitor's performance (P<0.05). The Kruskal-Wallis test showed significant differences (P<0.05) in monitor performance for all variables investigated, except for the weather and the clinic in which the monitors were placed. Conclusion: The vast performance variation present between computer monitors implies the need for a review of monitor selection, calibration, and viewing conditions.

• Imaging Science in Dentistry
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• v.48 no.4
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• pp.277-281
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• 2018

Purpose: This study was performed to investigate the relationship between sleep bruxism(SB) and pulpal calcifications in young women. Materials and Methods: A total of 100 female participants between 20 and 31 years of age who were referred to our radiology clinic for a dental check-up, including 59 SB and 41 non-SB patients, were sampled for the analysis. SB was diagnosed based on the American Academy of Sleep Medicine criteria. All teeth were evaluated on digital panoramic radiographs to detect pulpal calcifications, except third molars, teeth with root canal treatment, and teeth with root resorption. Binary logistic regression analysis was used to determine the risk factors for pulpal calcifications. The Spearman correlation coefficient was applied and the Pearson chi-square test was used for categorical variables. To test intra-examiner reproducibility, Cohen kappa analysis was applied. P values <.05 were considered to indicate statistical significance. Results: A total of 2800 teeth were evaluated (1652 teeth from SB patients and 1148 from non-SB patients), and 61% of patients had at least 1 dental pulpal calcification. No statistically significant relationship was found between SB and pulpal calcifications (P>0.05). In SB patients, the total number of pulpal calcifications was 129, while in non-SB patients, it was 84. Binary logistic analysis showed that SB was not a risk factor for the presence of pulpal calcifications(odds ratio, 1.19; 95% CI, 0.52-2.69, P>.05). Conclusion: No relationship was found between SB and pulpal calcifications.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.29 no.2
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• pp.423-433
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• 1999

Purpose : To assess the methods for the clinical evaluation of the longitudinal bone changes after implantation of tooth ash-plaster mixture into the defect area of human jaws. Materials and methods : Tooth ash-plaster mixtures were implanted into the defects of 8 human jaws. 48 intraoral radiograms taken with copper step wedge as reference at soon, 1st, 2nd, 4th, and 6th week after implantation of mixture were used. X-ray taking was standardized by using Rinn XCP device customized directly to the individual dentition with resin bite block. The images inputted by Quick scanner were digitized and analyzed by NIH image program. Cu­equivalent values were measured at the implanted sites from the periodic digital images. Analysis was performed by the bidirectional subtraction with color enhancement and the surface plot of resliced contiguous image. The obtained results by the two methods were compared with Cu­equivalent value changes. Results : The average determination coefficient of Cu-equivalent equations was 0.9988 and the coefficient of variation of measured Cu values ranged from 0.08~0.10. The coefficient of variation of Cu-equivalent values measured at the areas of the mixture and the bone by the conversion equation ranged from 0.06 ~0.09. The analyzed results by the bidirectional subtraction with color enhancement were coincident with the changes of Cu-equivalent values. The surface plot of the resliced contiguous image showed the three dimensional view of the longitudinal bone changes on one image and also coincident with Cu-equivalent value changes after implantation. Conclusion : The bidirectional subtraction with color enhancement and the surface plot of the resliced contiguous image was very effective and reasonable to analyze clinically and qualitatively the longitudinal bone change. These methods are expected to be applicable to the non-destructive test in other fields.

• Journal of the Korean Society of Radiology
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• v.7 no.6
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• pp.389-395
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• 2013

This study intended to investigate the optimum conditions for lumbar test that has the highest level of irradiation conditions among general test sites. To to this, the most widely used irradiation conditions in terms of statistics were set as standards; test groups applied with DMF were selected; tests groups suitable for clinical trials were selected by using suggested patient dose. Blind tests were conducted by 10 specialists and radiologists. The results suggested that under the optimum conditions, the radiation dose reduction of 2.09 mGy, 4.42 mGy and 3.65 mGy can be achieved in forward-backward test, lateral test and 4-direction test, respectively. There is a need of further studies on the optimization of irradiation conditions in accordance with the conditions of patients.

• Korean Journal of Digital Imaging in Medicine
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• v.14 no.2
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• pp.23-31
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• 2012

There are AEC mode and fix mode to exposure when the whole spine antero-posterior radiography is done by using DR equipment. This study compared the utility of fix mode to AEC mode, by evaluating organ dose and effective dose and by examining the quality of radiographic image. GE DEFINIUM 8000 and ART-200X Rando Phantom manufactured by Flukebiometical were used for this study. The Rando phantom was set in front of wall detector of X-rays equipment. AEC mode was set at 80kVp and Fix mode was set at 80kVp, 25mAs, 32mAs, 40mAs, and 50mAs. Whole spine AP image were aquired by combining C, T-L and L-S spine images obtained through 3 exposures. When obtaining C, T-L and L-S spine images, were checked for Air kerma (mGy) value calculated by UNFORS Xi meter attached at the phantom surface of center of radiation field. The effective and organ doses were compared by PCXMC program (PC-Based Monte Carlo Program). The quality of obtained radiographic image was evaluated visually by 3 radiologists using resolution chart. When the effective doses was calculated based on tissue weighting factor of ICRP-103, 1.278mSv was measured by AEC mode, and Fix mode measured 0.405mSv at 25mAs, 0.518mSv at 32mAs, 0.649mSv at 40mAs, and 0.810mSv at 50mAS. In addition, the organ dose measured with esposure at 25mAs by Fix mode was almost equivalent to the organ dose by AEC mode, at the esophagus, thyroid, oral mucosa, salivaly glands located at the cervical spine part, while the organ dose by Fix mode was in general lower than the organ dose by AEC mode at the other organs. When Fix mode at 32mAs, 40mAs, and 50mAs was compared to AEC mode for organ dose in 26 organs, AEC mode had higher measurement in 21 organs but not for than brain, trachea, thyroid, oral mucosa, and salivaly glands which are located at the cervical spine part. The image quality evaluated by resolution test chart was much higher with AEC mode than the quality with Fix mode at all exposure conditions. However, while the image quality of cervical spine exposured at 50mAs by Fix mode was lower than the quality of AEC mode, thoraco-lumbar spine and lumbo-sacral spine were calculated and the quality was similar to AEC mode. Scoliosis occurs mainly at thoraco-lumbar and lumbo-sacral spine, not at cervical spine. Compared to AEC mode, Using the appropriate protocol (80kVp, 50mAs) of fix mode for whole spine AP radiography was thought to be useful because the image quality of the thoraco-lumar and lumbo-sacral spine was similar on AEC mode, Also organ and effective doses can be decreased with Fix mode. Therefore, It is considered that fix mode can be used properly with AEC mode for whole spine AP radiography when considering patient's body posture.