• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.322-323
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• 2002

Partial volume averaging effect of PET data influences on the accuracy of quantitative measurements of regional brain metabolism because spatial resolution of PET is limited. The purpose of this study was to evaluate the accuracy of partial volume correction carried out on $^{18}$ F-PET images using Hoffman brain phantom. $^{18}$ F-PET Hoffman phantom images were co-registered to MR slices of the same phantom. All the MR slices of the phantom were then segmented to be binary images. Each of these binary images was convolved in 2 dimensions with the spatial resolution of the PET. The original PET images were then divided by the smoothed binary images in slice-by-slice, voxel-by-voxel basis resulting in larger PET image volume in size. This enlarged partial volume corrected PET image volume was multiplied by original binary image volume to exclude extracortical region. The evaluation of partial volume corrected PET image volume was performed by region of interests (ROI) analysis applying ROIs, which were drawn on cortical regions of the original MR image slices, to corrected and original PET image volume. From the ROI analysis, range of regional mean values increases of partial volume corrected PET images was 4 to 14%, and average increase for all the ROIs was about 10% in this phantom study. Hoffman brain phantom study was useful for the objective evaluation of the partial volume correction method. This MR-based correction method would be applicable to patients in the. quantitative analysis of FDG-PET studies.

• Journal of the Korean Society of Radiology
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• v.82 no.4
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• pp.889-902
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• 2021

Purpose To assess the diagnostic performance of contrast-enhanced ultrasound (CEUS) for additional MR-detected enhancing lesions and to determine whether or not kinetic pattern results comparable to dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) of the breast can be obtained using the quantitative analysis of CEUS. Materials and Methods In this single-center prospective study, a total of 71 additional MR-detected breast lesions were included. CEUS examination was performed, and lesions were categorized according to the Breast Imaging-Reporting and Data System (BI-RADS). The sensitivity, specificity, and diagnostic accuracy of CEUS were calculated by comparing the BI-RADS category to the final pathology results. The degree of agreement between CEUS and DCE-MRI kinetic patterns was evaluated using weighted kappa. Results On CEUS, 46 lesions were assigned as BI-RADS category 4B, 4C, or 5, while 25 lesions category 3 or 4A. The diagnostic performance of CEUS for enhancing lesions on DCE-MRI was excellent, with 84.9% sensitivity, 94.4% specificity, and 97.8% positive predictive value. A total of 57/71 (80%) lesions had correlating kinetic patterns and showed good agreement (weighted kappa = 0.66) between CEUS and DCE-MRI. Benign lesions showed excellent agreement (weighted kappa = 0.84), and invasive ductal carcinoma (IDC) showed good agreement (weighted kappa = 0.69). Conclusion The diagnostic performance of CEUS for additional MR-detected breast lesions was excellent. Accurate kinetic pattern assessment, fairly comparable to DCE-MRI, can be obtained for benign and IDC lesions using CEUS.

• Imaging Science in Dentistry
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• v.53 no.3
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• pp.265-266
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• 2023

• Journal of Korean society of Dental Hygiene
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• v.9 no.2
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• pp.111-124
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• 2009

This study analyzes through the review of literature and laws the exposure time, clinical frequency, and radiation exposure of intraoral and extraoral radiography as well as of panoramic radiography performed by dental hygienists in dental clinics, compares the dental radiology curriculums of radiological science and dental hygiene departments, and proposes the expansion of dental hygienists' radiography operations. The radiology curriculums were compared between the radiological science and dental hygiene departments of colleges. For new analysis by radiography for dental diagnosis, the exposure time, radiation absorbed dose, effective dose, and number of days of natural radiation were compared by the type of oral radiation films and radiographical techniques proposed by domestic and international studies. The exposure time of panoramic radiography is 15 seconds and it takes about two minutes for completion, whereas the exposure time of the standard radiography is 0.2~0.8 seconds and it takes 10 times longer for completion of the radiography of full mouth than the panoramic radiography. The standard radiography can cause distortions of radiation at severely curved parts of dental arch and palatopharyngeal reflex. However, panoramic radiography can be performed even for lock jaw patients, causes less inconvenience to patients and is much simpler than the standard radiography. The percentage of dental clinics where radiography is performed by dental hygienists was 92.0%, and the percentage of standard film radiography by dental hygienists was 98% whereas the percentage of panoramic radiography by dental hygienists was 92%. For the absorbed dose which is an indicator of radiation exposure, the When the effective dose which is an indicator of the danger of radiation exposure was converted to the number of days of natural radiation, it was 3.3 days for panoramic radiography, but 13.9 days for the full mouth standard radiography by bisecting angle technique which was 4.2 times longer than the panoramic radiography. There were two colleges that had a dental radiology course with two credits in the departments of radiological science. The credits for dental radiology courses in the department of dental hygiene ranged varied by college, ranging from 3 to 8; on average, the theory course was 2.2 credits and the practice course was 2.02 credits. To summarize the above results, the percentage of dental clinics where panoramic radiography is performed by dental hygienists under the guidance of dentists is high. Panoramic radiography has become an essential facility for dental clinics. It is faster than standard film radiography and less dangerous due to low radiation exposure. Panoramic radiography is a simple mechanical job that does not require training of oral radiography by radiotechnologist. Because panoramic radiography is one of major operations which must be performed at all times in dental clinics, it must be designated as intraoral technique rather than extraoral technique, or legalized for inclusion in the scope of operations of dental hygienists.

• Journal of the Korean Society of Radiology
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• v.18 no.3
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• pp.203-212
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• 2024

The purpose of this study was to survey by the veterinary hospital Specialists (VHSs) and radiology students (RSs) for radiology curriculum development veterinary hospital (VH), and for veterinary hospital radiological technologists (VHRTs). VHSs were surveyed to regarding the basic information and radiological examination training, radiological examination experience, anatomy physiology, radiation safety management training, radiation biology training. RSs were surveyed to regarding the basic information and career paths, VH awareness, and VH-related department environments. The survey results were quantitatively entered into Excel and then analyzed using the SPSS ver. 26.0. The students were aged by 22.6 years old, and out of 171 students, male and female were 92 and 79 espectively. In employment career paths, 62.6% of all subjects responded that employment prospects at medical institutions were good. Employment prospects outside of medical institutions, VH had the highest number of students. Of the 83 students who responded that they wanted to work at a VH, 64 students liked animals, and 47 students the high potential for advancement. Of the 159 students who responded that there is potential for development of VH, 96.2% responded that it was due to the increase in companion animals. In the VH-related department environment, 94.7% responded that there was no related equipment, and 72.5% responded that the department needed to open animal care courses and 82.5% anatomy and physiology courses. 76.6% responded that they would be willing to take animal-related courses if they were offered. Among the 20 VHSAs, 4 had no experience in radiological examination of animals, 2 VHRTs, and 2 others. There were 7 people who had not received training in animal radiography, and 2 VHRTs had not received training in animal care and animal anatomy and physiology. This study is expected to be helpful in developing a radiology curriculum for VHRTs in the future.

• Imaging Science in Dentistry
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• v.45 no.2
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• pp.103-108
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• 2015

Bony fusion between the mandibular condyle and skull base involves temporomandibular joint (TMJ) bony ankylosis. This condition might originate from trauma, infection, or systemic disease. TMJ adhesion can develop after synovial damage. Both TMJ ankylosis and adhesion lead to functional impairment and pain. Here, we present a case of a 50-year-old female who had bony ankylosis of the right TMJ and adhesion of the left TMJ. She had otitis media in the right ear. A large mass in the right TMJ was observed on computed tomograph. Magnetic resonance image showed a large fused bone mass with normal bone marrow in the right TMJ and flattening of the condyle with a thin disk in the left TMJ. Gap arthroplasty with temporal fascia was performed on the right TMJ, and discectomy, high condylectomy, and coronoidectomy were performed on the left TMJ. During a 2-year follow-up after surgery, the patient had no recurrence.

• Journal of Sensor Science and Technology
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• v.26 no.4
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• pp.280-285
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• 2017

This paper presents a respiration measurement sleeping pillow based on pressure sensors. The respiration measurement sleeping pillow system consists of a sleeping pillow, an interface circuit, a respiration measurement system, and four force-sensitive resistor(FSR) sensors attached at the bottom of the sleeping pillow. The FSR sensors are used to detect the respiration signals induced by the body movement while breathing. The respiration signals of a twenty health man were measured and analyzed by utilizing the respiration measurement sleeping pillow system. The pillow system could detect the respiration signals and had similar characteristics to the chest type BIOPAC respiration sensor used by medical doctors. The respiration rates of ten subjects were also measured. The average measurement accuracy was about 98.8%. The research results showed that this pillow system can be used to detect and analyze the respiration signal when sleeping for the better sleep management.

• 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.

• Nuclear Engineering and Technology
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• v.56 no.9
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• pp.3898-3903
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• 2024

There is a lack of available data on the radioactivity levels of these materials, despite the potential risks they may pose to patients, dental technicians, and dentists. A total of forty samples were collected from different dental markets in Egypt. Using an NaI(Tl) detector, the gamma-ray spectrometer measured the activity levels of uranium-238, radium-226, thorium-232, and potassium-40. The findings revealed that the mean concentration of ²³⁸U (below the minimum detectable activity, MDA), ²²⁶Ra (135 ± 5 and 132 ± 5 Bq/kg), ²³²Th (187 ± 4 and 243 ± 8 Bq/kg), and ⁴⁰K (1560 ± 52 and 2501 ± 89 Bq/kg) in feldspar and zirconia (ZrO₂) dental ceramic samples, respectively, were all within the limits established by the International Organization for Standardization (ISO) and the European Commission (EC). The use of feldspar and zirconia dental ceramics to restore all teeth would result in an estimated maximum beta dose of 1.5 mGy/year to the oral tissue. The results suggest that there is no cause for concern regarding any additional beta dose to the oral cavity from the use of feldspar and zirconia dental ceramics.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.5
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• pp.3037-3040
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• 2013

Introduction: Mammography is the most basic modality in breast cancer imaging. However, the overlap of breast tissue depicted on conventional two-dimensional mammography (2DMMG) may create significant obstacles to detecting abnormalities, especially in dense or heterogeneously dense breasts. In three-dimensional digital breast tomosynthesis (3DBT), tomographic images of the breast are reconstructed from multiple projections acquired at different angles. It has reported that this technology allows the generation of 3D data, therefore overcoming the limitations of conventional 2DMMG for Western women. We assessed the detectability of lesions by conventional 2DMMG and 3DBT in diagnosis of breast cancer for Japanese women. Methods: The subjects were 195 breasts of 99 patients (median age of 48 years, range 34~82 years) that had been pathologically diagnosed with breast cancer from December 20, 2010 through March 31, 2011. Both conventional 2DMMG and 3DBT imaging were performed for all patients. Detectability of lesions was assessed based on differences in category class. Results: Of the affected breasts, 77 (75.5%) had lesions assigned to the same categories by 2DMMG and 3DBT. For 24 (23.5%) lesions, the category increased in 3DBT indicating improvement in diagnostic performance compared to 2DMMG. 3DBT improved diagnostic sensitivity for patients with mass, focal asymmetric density (FAD), and architectural distortion. However, 3DBT was not statistically superior in diagnosis of the presence or absence of calcification. Conclusions: In this study, 3DBT was superior in diagnosing lesions in form of mass, FAD, and/or architectural distortion. 3DBT is a novel technique that may provide a breakthrough in solving the difficulties of diagnosis caused by parenchyma overlap for Japanese women.