• Journal of the Korean Society of Radiology
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• v.14 no.5
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• pp.677-684
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• 2020

Miscentering in the left and right X axis direction during CT examination affects dose and quality. When the CT Gantry Isocenter and the center of the examination objective are matched using the Lateral Sliding Table, the image quality is improved and the exposure dose is reduced. CTDI Head Phantom (Kimda, Korea) and dosimeter (Ray Safe, Sweden) were used to measure dose comparison CTDI (mGy) due to center deviation, and Water Phantom (HITACHI, Japan) was used to measure noise to see the difference in uniformity due to center deviation. Measurements of doses for dose comparison CTDI (mGy) with a deviation showed that doses were consistently reduced and exact dose was not projected until they were moved to 80 mm by 20 mm from the Isocenter. SD values were measured to see the difference in uniformity due to center deviation and the noise continued to increase until it was moved by 20 mm to 80 mm. The range of collimation has increased by the extent of deviating from the center and the range of exposure has increased. Using the Lateral Sliding Table, you can easily adjust the Isocenter, increase the quality of the image by adjusting the Isocenter in areaa such as the cardiac examination of the location away from the Isocenter, Extreme bone and Shoulder, and greatly reduce the collimation to the Isocenter, so it can be used to reduce unnecessary exposure dose.

• Journal of radiological science and technology
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• v.38 no.3
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• pp.187-197
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• 2015

This study analysed the effectiveness of aluminium(Al) filter in the added compound filtration for the removal of characteristic radiation by energy spectrum and image evaluation. 0.1, 0.2, 0.3 mm copper with and without 1 mm Al were evaluated. The energy spectrum was measured using the GATE and evaluated separately by each energy. Image quality was evaluated by PSNR, MAE, MSE, CNR, SNR and qualitative analysis was performed by seven items for resolution and contrast from chest x-ray criteria of National Cancer Screening and Cardiovascular evaluation table. In the analysis of the quality of the energy per photon spectrum with the exception of a low energy region, without Al were superior in all area. PSNR MAE, MSE, CNR, SNR and qualitative analysis were the same or slightly better. PSNR was over 30 dB and all significant and the p>0.05 in the T-test of qualitative analysis. The energy spectrum and image quality have little difference between before and after use of Al filter. Therefore, it is effective to use the Al filter for the radiation dose management with the compensation capability of DR system.

• Science of Emotion and Sensibility
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• v.16 no.3
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• pp.373-386
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• 2013

In this research, we specify the image consumers' preferred image quality ranges based on objective image quality evaluation factors and follow a method which measures preference of the natural image scenes. In other words, according to No-Reference, we select dynamic range, color, and contrast as factors of image quality measurements. For collecting sample images, we choose the preferred 200 landscapes which have over 30 recommendations by image consumers on the internet photo gallery. According to the scores of three objective factors of image quality measurements, the final expected score which means the image quality preference is measured and its total score is 100 points. In the main test, the actual image sample shows dynamic range 10 stop, LAB mean value L:54.7, A:2.96, B:-15.84, and RSC contrast 376.9. Total 200 image samples' normal distribution z value represents in dynamic range 0.21, LAB mean value L:0.15, A:0.38, B:0.13, and RSC contrast 0.08. In the standard normal distribution table, we can convert the z value as a percentage; dynamic range is 8.32%, LAB mean value is L:5.96%, A:14.8%, B:5.17%, and RSC contrast is 3.19%. And then, we convert the percentage values into the scores of 100; dynamic range is 91.68, LAB mean value is 91.36, and RSC contrast is 96.81. Therefore, we can conclude that the sample image's total mean score is 94.99 based on three objective image quality factors. Throughout our proposed image quality assessment model, we can measure the preference value of natural scenes. Also, we can specify the preferred image quality representation ranges and measure the expected image quality preference.

• Journal of the Korean Society of Food Culture
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• v.24 no.5
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• pp.467-477
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• 2009

This study was conducted to investigate and analyze food related and space related elements of popular Vietnamese restaurants in Hong Kong to identify restaurant images related to food, to examine how Vietnamese traditions are applied to such restaurants, and ultimately, to get their implications for us. Luxury Vietnamese restaurants in Hong Kong tended to be located in major office buildings and famous shopping malls in the downtown area; therefore, they were highly accessible to foreigners. In addition, most Vietnamese restaurants were quite formal in size or atmosphere. The food-related elements of the luxury restaurants reproduced traditional menus, but the table setting and service generally adopted a formal Western style setting. The presentation of foods was also creative and contemporary, to suit international customers' tastes. Regarding the spatial elements, restaurants serving traditional menus had interiors influenced by the French colonial period, while those serving contemporarily adapted menus had interiors with simple contemporary images emphasized by Vietnamese traditional decorations. These characteristics allowed foreigners from diverse countries to access the restaurants without a sense of rejection. Casual restaurants were primarily exposed to many people on busy roadsides, but they tended to be inferior in terms of size and quality. Apart from size and price level, food-related elements failed to reflect Vietnamese unique traditional characteristics. The outward appearance consisted of basic construction materials (glass, chassis, and bamboo) instead of those representing Vietnamese architecture. Additionally, the interior of the casual restaurants contained traditional elements or objects more frequently than luxury restaurants, but they looked rather disorderly and lacked harmony. Overall, the image of casual restaurants was degraded by the use of cheap and low quality finishing materials and furniture. The results of this study may be useful for organizations promoting the Branding of Korea or businesspeople and designers promoting the globalization of Korean foods.

• Journal of the Korean Society of Radiology
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• v.6 no.5
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• pp.357-363
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• 2012

The purpose of this study on head computed tomography scan corporate reorganization adaptive iteration algorithm using the statistical noise, and quality assessment, reduction of dose was evaluated. Head CT examinations do not apply ASIR group [A group], ASIR 50 applies a group [B group] were divided into examinations. B group of each 46.9 %, 48.2 %, 43.2 %, and 47.9 % the measured in the phantom research result of measurement of CT noise average were reduced more than A group in the central part (A) and peripheral unit (B, C, D). CT number was measured with the quantitive analytical method in the display-image quality evaluation and about noise was analyze. There was A group and difference which the image noise notes statistically between B. And A group was high so that the image noise could note than B group (31.87 HUs, 31.78 HUs, 26.6 HUs, 30.42 HU P<0.05). The score of the observer 1 of A group evaluated 73.17 on 74.2 at the result 80 half tone dot of evaluating by the qualitative evaluation method of the image by the bean curd clinical image evaluation table. And the score of the observer 1 of B group evaluated 71.77 on 72.47. There was no difference (P>0.05) noted statistically. And the inappropriate image was shown to the diagnosis. As to the exposure dose, by examination by applying ASIR 50 % there was no decline in quality of the image, 47.6 % could reduce the radiation dose. In conclusion, if ASIR is applied to the clinical part, it is considered with the dose written much more that examination is possible. And when examination, it is considered that it becomes the positive factor when the examiner determines.

• Journal of the Korean Society of Radiology
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• v.9 no.7
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• pp.467-471
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• 2015

This study's purpose is improve image quality to keep accurate tube angle in order to recognize distortion degree conditions by patient's position or tube angle and to provide exact clinical informations when taking chest AP projection for patient which have L-tube in stomach. The experimental equipment was ELMO-T6S by SHIMADZU corporation, then we put L-tube which attached 1 mm gap scales ruler on chest phantom surface. The experiment set by 90 kVp, 4 mAs, 120 cm distance. Each phantom position which changed supine, 30degree, 45degree, 60degree on the table exposured direct, ${\pm}5degree$, ${\pm}10degree$, ${\pm}15degree$ to head and feet directions. As a result, L-tube tip's position was changed by patient's position and tube angle. When patient's position is supine, tip's position change was lower than 30degree, 45degree, 60degree. We have to adjust patient's position or tube angle in order to occur image distortion by fault tube angle when confirming correct position L-tube tip through chest x-ray. Also, Radiological technologist try to make accurate evaluation index for satisfied L-tube insertion.

• Journal of Broadcast Engineering
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• v.13 no.2
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• pp.222-235
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• 2008

Recently, as growing of high definition media services like HDTV and IPTV, fast moving picture manipulation techniques need to meet what those services require. Especially, a fast reduced-size image extracting method is required in the areas of video indexing and video summary Conventional DC image extracting methods, however, can't be applied to H.264/AVC streams since a spatial domain prediction scheme is adopted in H.264/AVC intra mode. In this paper, we propose a theoretical method for extracting a thumbnail image from an H.264/AVC intra frame in the frequency domain. Furthermore, the proposed scheme can extract the thumbnail very fast since all operations are applied to transform coefficients directly, after a general equation for the thumbnail extraction in nine H.264/AVC intra prediction modes is introduced, an LUT(Look Up Table) for each mode is designed. Through the implementation and performance evaluation, while the subject quality difference between the output of our scheme and a conventional output is negligible, the former can extract the thumbnail faster then the latter by up to 63%.

• Journal of radiological science and technology
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• v.32 no.4
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• pp.361-370
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• 2009

The image quality management of bone mineral density is the responsibility and duty of radiologists who carry out examinations. However, inaccurate conclusions due to lack of understanding and ignorance regarding the methodology of image quality management can be a fatal error to the patient. Therefore, objective of this paper is to understand proper image quality management and enumerate methods for examiners and patients, thereby ensuring the reliability of bone mineral density exams. The accuracy and precision of bone mineral density measurements must be at the highest level so that actual biological changes can be detected with even slight changes in bone mineral density. Accuracy and precision should be continuously preserved for image quality of machines. Those factors will contribute to ensure the reliability in bone mineral density exams. Proper equipment management or control methods are set with correcting equipment each morning and after image quality management, a phantom, recommended from the manufacturer, is used for ten to twenty-five measurements in search of a mean value with a permissible range of ${\pm}1.5%$ set as standard. There needs to be daily measurement inspections on the phantom or at least inspections three times a week in order to confirm the existence or nonexistence of changes in values in actual bone mineral density. in addition, bone mineral density measurements were evaluated and recorded following the rules of Shewhart control chart. This type of management has to be conducted for the installation and movement of equipment. For the management methods of inspectors, evaluation of the measurement precision was conducted by testing the reproducibility of the exact same figures without any real biological changes occurring during reinspection. Bone mineral density inspection was applied as the measurement method for patients either taking two measurements thirty times or three measurements fifteen times. An important point when taking measurements was after a measurement whether it was the second or third examination, it was required to descend from the table and then reascend. With a 95% confidence level, the precision error produced from the measurement bone mineral figures came to 2.77 times the minimum of the biological bone mineral density change. The value produced can be stated as the least significant change (LSC) and in the case the value is greater, it can be stated as a section of genuine biological change. From the initial inspection to equipment moving and shifter, management must be carried out and continued in order to achieve the effects. The enforcement of proper quality control of radiologists performing bone mineral density inspections which brings about the durability extensions of equipment and accurate results of calculations will help the assurance of reliable inspections.

• Journal of Biomedical Engineering Research
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• v.39 no.1
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• pp.48-54
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• 2018

In this study, We developed a Ancillary device for child radiography for X-ray of children under 5 years old and verified its effectiveness. Chest X-rays of children younger than 5 years of age were performed by Supine method at the position of Table detector, Short - Source to Image Receptor Distance(SID). Existing Supine and Short -SID imaging methods cause many problems, such as errors in image reading and excessive radiation exposure dose to patients, but the use of an Ancillary device for child radiography(ADCR) solves these problems. A total of 160 children were divided into the Upright group using ADCR and Supine group without ADCR. The chest X-ray image was visually evaluated by two radiologists with reference to the European Commission's List of Quality Criteria for Diagnostic Radiographic Images in Pediatrics. The total score of the qualitative evaluation was 5.15% higher in the chest upright method using ADCR than in the chest supine method without ADCR, and the chest upright method score was higher than that of the chest supine method in items 1 to 7. whether infants have deep inspiration or not, 4.87% higher for item 1, whether infants rotate or not and the degree of tilting, 0% higher for the item 2, the reproduction of image from just above apices of lungs to T12/L1, 0% for the item 3, reproduction of the vascular pattern in central 2/3 of the lungs, 6.92% higher for the item 4, reproduction of the trachea and the proximal bronchi, 12.9% higher for the item 5, visually sharp reproduction of the diaphragm and costo-phrenic angles, 10% higher for the item 6, reproduction of the spine and paraspinal structures and visualisation of the retrocardiac lung and the mediastinum, and 3.65% higher for the item 7. Items 2 and 3 showed no statistically significant differences(P > 0.05), and items 1, 4, 5, 6, and 7 showed statistically significant differences(P < 0.05). In conclusion, Upright method using ADCR in pediatric chest X-ray is considered as a good alternative to existing Supine method.

• Proceedings of the Korea Contents Association Conference
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• 2009.05a
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• pp.1141-1149
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• 2009

In Bone Mineral Density(BMD) measurements, accuracy and precision must be superior in order to know the small changes in bone mineral density and actual biological changes. Therefore the purpose of this study is to increase the reliability of bone mineral density inspection through appropriate management of image quality from machines and inspectors. For the machine management method, the recommended phantom from each bone mineral density machine manufacturer was used to take 10~25 measurements to determine the standard amount and permitted limit. On each inspection day, measurements were taken everyday or at least three times per week to verify the whether or not change existed in the amount of actual bone mineral density. Also evaluations following Shewhart control chart and CUSUM control chart rules were made for the bone mineral density figures from the phantoms used for measurements. Various forms of management became necessary for machine installation and movement. For the management methods of inspectors, evaluation of the measurement precision was conducted by testing the reproducibility of the exact same figures without any real biological changes occurring during reinspection. There were two measurement methods followed: patients were either measured twice with 30 measurements or three times with 15 measurements. An important point to make regarding measurements is that after the first inspection and any other inspection following, the patient was required to come off the inspection table completely and then get back on for any further measurements. With a 95% confidence level, the precision error produced from the measurement bone mineral figures produced a precision error of 2.77 times the minimum of the biological bone mineral density change (Least significant change: LSC). In order to assure reliability in inspection, there needs to be good oversight of machine management and measurer for machine operation and inspection error. Accuracy error in machines needs to be reduced to under 1% for scientific development in bone mineral density machines.