• Journal of the Korea Safety Management & Science
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• v.13 no.2
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• pp.91-96
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• 2011

The purpose of this study was to minimize of entrance surface dose (ESD) at the eye using high kVp technique in the computed radiography. We used REX-650R (Listem, Korea) general X-ray unit, and external detector with ESD dosimeter of Piranha 657 (RTI Electronics, Sweden). We used head of the whole body phantom. The total 64 images of X-ray anterior-posterior of skull were acquired using the film/screen (F/S) method and the digital of computed radiography method. The three radiology professor of more 10 years of clinical career evaluated a X-rays images in the same space by 5-point scale. The external detector was performed measurement of ESD of three times by same condition on the eye of the head phantom. The good image quality in the F/S method (90 kVp, 2.5 mAs) showed at the minimized ESD of 0.310 ${\pm}$ 0.001 mGy. the good image quality in the computed radiography method (90 kVp, 2.0 mAs) showed at the minimized ESD of 0.180 ${\pm}$ 0.002 mGy (P = 0.002). Finally the radiation dose could reduced about 50% in the computed radiography method more than the F/S method. In addition the eye entrance surface dose using high kVp technique with the computed radiography was reduced 92% more than conventional technique (F/S method).

• 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.

• 대한방사선방어학회:학술대회논문집
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• 2010.04a
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• pp.128-129
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• 2010

• Restorative Dentistry and Endodontics
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• v.40 no.1
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• pp.58-67
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• 2015

Objectives: This study aimed to compare the accuracy of conventional intraoral (CI) radiography, photostimulable phosphor (PSP) radiography, cone beam computed tomography (CBCT) and multidetector computed tomography (MDCT) for detection of strip and root perforations in endodontically treated teeth. Materials and Methods: Mesial and distal roots of 72 recently extracted molar were endodontically prepared. Perforations were created in 0.2, 0.3, or 0.4 mm diameter around the furcation of 48 roots (strip perforation) and at the external surface of 48 roots (root perforation); 48 roots were not perforated (control group). After root obturation, intraoral radiography, CBCT and MDCT were taken. Discontinuity in the root structure was interpreted as perforation. Two observers examined the images. Data were analyzed using Stata software and Chi-square test. Results: The sensitivity and specificity of CI, PSP, CBCT and MDCT in detection of strip perforations were 81.25% and 93.75%, 85.42% and 91.67%, 97.92% and 85.42%, and 72.92% and 87.50%, respectively. For diagnosis of root perforation, the sensitivity and specificity were 87.50% and 93.75%, 89.58% and 91.67%, 97.92% and 85.42%, and 81.25% and 87.50%, respectively. For detection of strip perforation, the difference between CBCT and all other methods including CI, PSP and MDCT was significant (p < 0.05). For detection of root perforation, only the difference between CBCT and MDCT was significant, and for all the other methods no statistically significant difference was observed. Conclusions: If it is not possible to diagnose the root perforations by periapical radiographs, CBCT is the best radiographic technique while MDCT is not recommended.

• Korean Journal of Digital Imaging in Medicine
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• v.7 no.1
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• pp.7-13
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• 2005

Purpose : Image plate (IP) is substituted for film in computed radiography. This study is to investigate into a variation of contrast and detail by the number used of image plate in computed radiography. Materials and Methods : A Contrast-Detail(CD)-RAD 2.0 phantom(Nijmegen hospital, The Netherlands) was used for this study. The computed radiography(CR) CD-RAD phantom images were acquired at 40 kVp, 160 mA, 1.6 mAs, and small focus with the Shimadzu general radiography UD-150B-10 system and Fuji FCR 5000 image process system with speed of 200. The IP used including once, 5000 times, and 10000 times also was used. The numerical value of image quality figures (IQF) was produced by CD-RAD analyser(the program is installed in the directory), and then contrast-detail curve was drawn. Results : In this study, the value of IQF was 3.53 in IP used once, 3.40 in 5000 times, and 3.22 in 10000 times. Conclusions : There was a variation of contrast-detail curve by the number used of IP with contrast-detail phantom in computed radiography. Therefore, it is necessary that the IP with lower IQF and a shift of contrast-detail curve to the lower left part is used.

• Journal of Radiation Protection and Research
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• v.35 no.1
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• pp.26-33
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• 2010

A computed Radiography (CR) system by use of reusable Image Plate (IP) offers a convenient and reliable way to replace a conventional film-screen system for NDT (non-destructive testing) field. The quality of a radiography to detect a defect of welded objects depends on the procedure embracing several factors such as measurement conditions, image plate type/class, radiation energy, radiation type, and source to image plate distance. Also, the ability of images to detect a flaw reduces with increasing object thickness. In the study, the properties of gamma ray source were summarized for NDT field and inspection images of CR image system manufactured by FUJI were acquired using $^{75}Se$ and $^{192}Ir$ with welded objects. We analyzed the gray scale of hole defect image by using XCAP image processing program and calculated the image contrast and SNR in definition. Also the sesitivities of image quality indicator(IQI) were calculated for hot and cooling tube image of $^{75}Se$ and $^{192}Ir$.

• Imaging Science in Dentistry
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• v.51 no.4
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• pp.407-412
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• 2021

Purpose: The purpose of this study was to evaluate the accuracy of virtual 3-dimensional (3D) cephalograms constructed using the principle of biplanar radiography by comparing them with cone-beam computed tomography (CBCT) images. Materials and Methods: Thirty orthodontic patients were enrolled in this study. Frontal and lateral cephalograms were obtained with the use of a head posture aligner and reconstructed into 3D cephalograms using biplanar radiography software. Thirty-four measurements representing the height, width, depth, and oblique distance were computed in 3 dimensions, and compared with the measurements from the 3D images obtained by CBCT, using the paired t-test and Bland-Altman analysis. Results: Comparison of height, width, depth, and oblique measurements showed no statistically significant differences between the measurements obtained from 3D cephalograms and those from CBCT images (P>0.05). Bland-Altman plots also showed high agreement between the 3D cephalograms and CBCT images. Conclusion: Accurate 3D cephalograms can be constructed using the principle of biplanar radiography if frontal and lateral cephalograms can be obtained with a head posture aligner. Three-dimensional cephalograms generated using biplanar radiography can replace CBCT images taken for diagnostic purposes.

• Imaging Science in Dentistry
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• v.32 no.2
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• pp.61-66
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• 2002

Purpose: To compare the bone height of implant sites measured using panoramic radiography and spiral CT. Materials and Methods : The available bone height was determined for 263 maxillary and mandibular implant sites in 59 patients. Distortion was calculated using the metal bar for the panoramic radiographs. Results: Significant differences in mean bone height between the two imaging modalities were found in maxillary and mandibular anterior regions (p<0.05). The mean difference in bone height recorded by the two techniques was smallest in the maxillary and mandibular molar areas (0.8 mm), and greatest in the mandibular anterior region (1.3 mm). With the exception of the mandibular anterior region, ninety percent of all the sites showed measurement differences within 2 mm. Conclusion: A safety margin of 2 to 3 mm is called for when utilizing panoramic radiography, otherwise additional imaging modality such as computed tomography is necessary to obtain accurate measurements.

• Journal of radiological science and technology
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• v.14 no.2
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• pp.9-14
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• 1991

Chest radiograms obtained by using Fuji Computed Radiography(FCR) system were compared to conventional film/screen radiograms. The FCR images showed better image quality in diagnostic informations than the conventional chest images. In FCR, the radiation exposure to patient for chest examination could be reduced up to one tenths of conventional chest examination. The main advantages or FCR were considered to depend on the contrast processing and frequency processing properties. The use of FCR in clinical work may improve both diagnostic quality and radiation exposure.

• 대한방사선방어학회:학술대회논문집
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• 2009.04a
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• pp.238-239
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• 2009