• Journal of the Korean Society of Radiology
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• v.16 no.2
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• pp.163-168
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• 2022

Linear detectors composed of several modules have been widely used in industrial in-line inspection. Two dimensional image obtained from the linear detector shows line artifact at the connection part of each module. In this study, we proposed a method to remove the line artifact using the flat-field correction and a wedge phantom image. Conventional flat-field correction has been applied to remove the artifact, however there are still line artifacts even after applying correction. It was found that two edge pixels at the connection part of two modules were over-corrected after the flat-field correction. Those edge pixels was corrected by using the correction factor obtained from an image of the wedge phantom, and images removed line artifacts were obtained. It is necessary to improve the method obtained manually the correction factor from the image of the wedge phantom.

• Journal of the Korean Society of Radiology
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• v.17 no.2
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• pp.223-230
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• 2023

This study attempted to concider the morphological change of red blood cells after whole body irradiation. Blood samples used red blood cells of white mice and mouse after irradiation. Transmission electron microscope observation results, Anisocytosis was observed in red blood cells 20 days after 5 Gy irradiation. Triangle and tetrapod were observed for small red blood cell types. Poikilocytosis, sickle-shaped Drepanocyte, and Acantocyte were observed in general-sized red blood cells. Schizocyte was observed in red blood cells 20 days after 7 Gy irradiation. Scanning electron microscope observation results, Dacryocyte was observed with microcytes. It was also confirmed that red blood cells were get tangled with each other. In addition, polygonal shapes and half-moon shapes were also observed. In conclusion, it is judged that the modified form of pathological study is more important than the numerical change in the study of red blood cells by radiation exposure. In conclusion, it was confirmed that modified morphological studies are more important than numerical changes in the study of red blood cells by radiation exposure.

• Journal of the Korean Society of Radiology
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• v.17 no.3
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• pp.417-422
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• 2023

In this study, normal saline was diluted with the contrast medium at a certain ratio for the purpose of reducing the image quality poor and side effects caused by the contrast medium during CT examination. At this time, by finding the energy level of DECT that can compensate for the decrease in contrast of the image according to the degree of dilution, the usefulness of applying DECT for compensating the difference in image contrast was investigated through comparative analysis by applying SNR, CNR, and SSIM. As a result, when a dilution ratio of 4 (contrast medium): 6 (normal saline) and the energy level of DECT of 65 keV were applied, the contrast difference was the most similar to that when using the undiluted contrast medium. At this time, SNR was 813.71 ± 37.6, CNR was the highest at 921.87 ± 17.1, and SSIM index was measured at 0.851, which is the most similar to 1. The results of this study are meaningful in providing basic information for finding the appropriate dilution rate and energy level for each examination site through future clinical studies. It is believed that it can be reduced.

• Imaging Science in Dentistry
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• v.53 no.2
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• pp.101-108
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• 2023

Purpose: The aim of this study was to conduct a scoping review and meta-analysis to provide overall estimates of the recall and precision of artificial intelligence for detection and segmentation using oral and maxillofacial cone-beam computed tomography (CBCT) scans. Materials and Methods: A literature search was done in Embase, PubMed, and Scopus through October 31, 2022 to identify studies that reported the recall and precision values of artificial intelligence systems using oral and maxillofacial CBCT images for the automatic detection or segmentation of anatomical landmarks or pathological lesions. Recall (sensitivity) indicates the percentage of certain structures that are correctly detected. Precision (positive predictive value) indicates the percentage of accurately identified structures out of all detected structures. The performance values were extracted and pooled, and the estimates were presented with 95% confidence intervals(CIs). Results: In total, 12 eligible studies were finally included. The overall pooled recall for artificial intelligence was 0.91 (95% CI: 0.87-0.94). In a subgroup analysis, the pooled recall was 0.88 (95% CI: 0.77-0.94) for detection and 0.92 (95% CI: 0.87-0.96) for segmentation. The overall pooled precision for artificial intelligence was 0.93 (95% CI: 0.88-0.95). A subgroup analysis showed that the pooled precision value was 0.90 (95% CI: 0.77-0.96) for detection and 0.94 (95% CI: 0.89-0.97) for segmentation. Conclusion: Excellent performance was found for artificial intelligence using oral and maxillofacial CBCT images.

• Journal of the Korean Society of Radiology
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• v.17 no.5
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• pp.717-723
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• 2023

Liver disease is highly associated with death, and other abdominal diseases are also important causes affecting a person's lifespan, and a CT scan is essential when treating abdominal diseases. High radiation exposure is essential to create images that are good for reading, but managing the patient's radiation exposure is also essential. In this study, a post-processing wavelet algorithm was proposed to improve the image quality of abdominal CT images. Wavelets have the disadvantage of having to set a threshold value depending on the type of input image. Therefore, we experimentally proposed the threshold value of the wavelet and evaluated whether the image quality was effective. As a result of the experiment, the optimal threshold value for abdominal CT images was calculated to be 50. In the case of image 1, noise was improved by 49% and in the case of image 2, by 29%, and the contrast also increased. if the results of this study are applied for post-processing after abdominal CT, image quality can be improved and it will be helpful in disease diagnosis.

• Journal of the Korean Society of Radiology
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• v.17 no.6
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• pp.819-825
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• 2023

In this study, among chest CT examination conditions, the tube voltage was changed to 100 and 80 kVp and the reconstruction algorithm was changed to FBP, ASIR-V, and DLIR to compare and analyze changes in examination dose and image quality. As a result, when applying ASIR-V and DLIR at a tube voltage of 100 kVp, which is lower than the existing tube voltage, the dose is lowered while achieving image quality most similar to that when applying 120 kVp and FBP. especially, DLIR reconstructed images had excellent SNR and CNR at all tube voltages. In addition, the SSIM index was analyzed to be closest to 1, showing the highest similarity to the original image. Therefore, when performing repeated chest CT examinations, the application of DLIR can reduce the examination dose by about 29.7%, which is expected to help solve some of the biggest problems with CT examinations, namely radiation exposure due to the examination.

• Journal of the Korean Society of Radiology
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• v.17 no.6
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• pp.859-863
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• 2023

In this study, simple and portable radiation detection system using X-ray intensifying screen, optical sensor and micro-controller unit for education was proposed. The system was simply composed of detection unit consisting of an optical sensor and intensifying screen, micro-controller unit, and was designed to be suitable for portable. Radiation was measured using developed detection system and absorbed dose dosimeter with changing tube voltage from 50 to 100 kVp. The tube current and SDD were fixed on 100 mAs and 100 cm, and dose were measured repeated ten times at each tube voltage. The response and linearity of the detection system were confirmed using the measured values. It was confirmed that the comparison measurement results of the detection system and absorbed dose dosimeter showed a high correlation(r : 0.998, p<.001). In this results, the feasibility of the detection system with intensifying screen and micro-controller unit based was confirmed, and we considered that the developed detection system could be applied to portable, compact, low cost system for education.

• Journal of the Korean Society of Radiology
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• v.17 no.6
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• pp.1001-1007
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• 2023

Dose limits are not applied to medical radiation exposure therefore justification and optimization should be essential for protecting radiation. This study explores methods to reduce exposure dose undergoing general radiation exam by bolus(tissue equivalent material) with keeping image quality. Hand PA projection with 50 kVp, 5 mAs, SID 100 cm, and 8×10 inch is referred by covered bolus of thickness 0, 3, 5, 8, and 10 mm for evaluation entrance dose and SNR. The entrance dose (μGy) to the hand by bolus thickness was 125.41±0.288, 106.85±0.255, 104.97±0.221, 91.68±0.299, and 90.94±0.106 showing a significant reduction in radiation exposure depending on if the bolus was used and bolus thickness. The SNR of the image was 13.997, 13.906, 12.240, 12.538, and 12.548 at each bolus thickness, showing no significant difference. It was confirmed that if appropriate thickness and size of bolus is used depending on the type of radiological imaging exam and the body site, a significant radiation dose reduction effect can be achieved without deteriorating image quality.

• Journal of the Korean Society of Radiology
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• v.18 no.2
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• pp.179-185
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• 2024

By applying the various energy spectrum imaging functions of DECT, To quantitatively distinguish between contrast agent and calcification, changes in image quality are analyzed by comparing CNR and SNR. We investigated the level of dose reduction during two scans and one VNC scan. As a result, contrast agent and calcification were best distinguished in the 70 keV area, CNR and SNR were excellent, and scan dose was reduced by about 26.5%. Therefore, by applying DECT, meaningful results were obtained that could visually and quantitatively distinguish between the intravascular contrast agent and the shade of calcification. If clinical research is conducted in the future considering the patient's age, gender, and body type, quantitative analysis of calcification will be possible even with intravascular contrast agent flowing in, which will have a significant effect in reducing the patient's scan dose and the burden of multiple scans.

• Journal of the Korean Society of Radiology
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• v.18 no.3
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• pp.231-237
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• 2024

Brain injury causes persistent disability in survivors, and epidural hematoma(EDH) and subdural hematoma (SDH) resulting from cerebral hemorrhage can be considered one of the major clinical diseases. In this study, we attempted to automatically segment and hematomas due to cerebral hemorrhage in three dimensions based on computed tomography(CT) images. An improved GVF(gradient vector flow) algorithm was implemented for automatic segmentation of hematoma. After calculating and repeating the gradient vector from the image, automatic segmentation was performed and a 3D model was created using the segmentation coordinates. As a result of the experiment, accurate segmentation of the boundaries of the hematoma was successful. The results were found to be good even in border areas and thin hematoma areas, and the intensity, direction of spread, and area of the hematoma could be known in various directions through the 3D model. It is believed that the planar information and 3D model of the cerebral hemorrhage area developed in this study can be used as auxiliary diagnostic data for medical staff.