• Journal of radiological science and technology
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• v.40 no.3
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• pp.371-376
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• 2017

Since in case of children, they are sensitive to the radiation compared to the adult and the potential exposure damage lasts longer, the exposure dose should be managed better than for the adult. Therefore, this study was conducted to observe the change in the chest x-ray image by the use of grid, which eliminates the scattering rays but increases the exposure dose during the child chest x-ray examination. As a research method, SNR, CNR and V. Vuichi were measured at 100 cm and 180 cm with the grid varying the kVp to 70, 90 and 110. In addition, SNR, CNR and V. Vuichi were measured fixing 100 cm and 180cm without grid and varying the dose to 6, 8 and 10 mAs. In the results of measuring them by fixing kVp, SNR, VNR and V. Vuichi were represented high when FID is 100cm. And in the results of meaduring them varying mAs, SNR, VNR and V. Vuichi were represented high when FID is 100cm. Currently in our country, the chest x-ray examination is performed at 180 cm. However, as the image is measured high when FID is 100 cm, in case of child, FID is deemed to be 100 cm.

• The Journal of the Korea Contents Association
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• v.17 no.9
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• pp.99-106
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• 2017

This study focused on the issue that when a diagnostic detector is found to have a defect, a patient would be exposed to radiation and image quality would be degraded. Though dose analysis, an experiment was conducted to evaluate detector performance as Signal to Noise Ratio (SNR) and Contrast to Noise Ratio (CNR). Absorbed dose, SNR and CNR were measured using a dosimeter and a tissue equivalent phantom. The experiment was conducted to compare whether the dose value shown after being attached to the back side of the phantom matches the dose value attached behind the detector, where in the conditions of skull, chest and abdomen were set at 75 kVp, 25 mAs, 110 kVp, 8 mAs, and 80 kVp, 20 mAs, respectively. As a result, there was a difference in that the dose values attached to the back side of the detector were 0.004 mGy, 0.006 mGy, 0.003 mGy, whereas those of the back side of the phantom were 0.006 mGy, 0.016 mGy, 0.017 mGy. In order to match both values, the condition was increased and SNR and CNR also increased from 88.32, 88.10, 4.09, 1.63, 87.94, 79.97 to 93.87, 93.75, 4.91, 4.03, 92.02, 84.92. Though this study, we found that when a detector is found to have a aging, it shortens the life of equipment and increases the dose of a patient, also the improvement effect of image quality is inadequate.

• Journal of the Korean Society of Radiology
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• v.5 no.3
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• pp.149-154
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• 2011

The purpose of this study was to examine the usefulness of diffusion weighted images in breast MRI by performing a quantitative comparative analysis in patients diagnosed with DCIS. On a 3.0T MR scanner, diffusion weighted images and ADC map images were obtained from 20 patients histologically diagnosed with ductal carcinoma in situ (DCIS). The findings from the quantitative image analysis are the following: The diffusion weighted images showed higher SNR and CNR at the lesion area. In addition, the ADC values were lower at the lesion area.

• Journal of radiological science and technology
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• v.40 no.1
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• pp.79-85
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• 2017

The purpose of this study was to measure contrast to noise ratio (CNR) and signal to noise ratio (SNR) according to change of reconstruction from region of interest (ROI) in breast positron emission tomography-computed tomography (PET-CT), and to analyze the CNR and SNR statically. We examined images of breast PET-CT of 100 patients in a University-affiliated hospital, Seoul, Korea. Each patient's image of breast PET-CT were calculated by using ImageJ. Differences of CNR and SNR among four reconstruction algorithms were tested by SPSS Statistics21 ANOVA test for there was statistical significance (p<0.05). We have analysis socio-demographical variables, CNR and SNR according to reconstruction images, 95% confidence according to CNR and SNR of reconstruction and difference in a mean of CNR and SNR. SNR results, with the quality of distributions in the order of PSF_TOF, Iterative and Iterative-TOF, FBP-TOF. CNR, with the quality of distributions in the order of PSF_TOF, Iterative and Iterative-TOF, FBP-TOF. CNR and SNR of PET-CT reconstruction methods of the breast would be useful to evaluate breast diseases.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.86-89
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• 2015

Quantitative Evaluation of Image Quality using Automatic Exposure Control This it leads, the relationship of control and image between of photographing condition, DR proper use method proposing. Chest phantom acquires Chest PA images which it follows in conditional change, Image evaluation factor (SNR (Signal to Noise Ratio), CNR (Contrast to Noise Ratio), PSNR (Peak Signal to Ratio), RMS (Root Mean Square)). It excepted RMS price, SNR, CNR, PSNR the case which uses AEC it came out being high The fact that the quality of image is better there was a case which does not use AEC. but Price it was slight. Image qualitative it was deficient in AEC use presence. Through this, the overall situation and most efficient use of radiation workers is better suited. But Passive AEC use would be appropriate for use rather than proactive AEC.

• Journal of the Korean Society of Radiology
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• v.5 no.1
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• pp.37-49
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• 2011

To examine the possible changes in the SNRs, CNRs, and ADC values for lumbar spines with metastasis based on the DW images before and after contrast agent injection taken from metastatic spinal cancer patients using a 1.5 T MR machine. The quantitative analysis revealed that in case of spinal cancer subjects, both SNRs and CNRs at all of those assessed locations significantly increased on the DWI after contrast agent injection compared to before, while on the ADC map images, SNRs significantly decreased. On the other hand, significantly decreased ADC values at all the assessed locations were found on the ADC map images. With reference to the normal group, significantly increased SNRs were found at all of the assessed locations on the DWI image after injection compared to before, while significantly decreased SNRs were found on the ADC map images. Also, significantly decreased ADC values at all the assessed locations were found on the ADC map images. For the qualitative analysis, after contrast agent injection, significantly increased signal intensities were found at the locations with spinal cancer on the DWI. In contrast, significantly decreased signal intensities were found on the ADC map images. The implication from the results showing that SNR and CNR significantly increased while ADC value significantly decreased at, above, and below the location of metastatic spinal cancer on DWI after contrast agent injection is that DWI obtained after contrast agent injection can be made available for wider application to vertebral disorders.

• The Journal of the Korea Contents Association
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• v.13 no.8
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• pp.275-283
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• 2013

The patient radiation dose is different depending on selection of Ion chamber when taking Chest PA which using AEC. In this paper, we studied acquiring the best diagnostic images according to selection of Ion chamber on AEC mode as well as minimizing patient radiation dose. Experimental methods were selection of Ion chamber and change of sensitivity under the same conditions as Chest PA projection. At AEC mode, two upper ion chambers sensors and one lower ion chamber sensor were divided into 7 cases according to selection of on/off. after measuring five times respectively, we obtained average value and calculated exposure dose. Image assessment was done with measured Modulation Transfer Function, Peak Signal to Noise Ratio, Root Mean Square, Signal to Noise Ratio, Contrast to Noise Ratio, Mean to Standard deviation Ratio respectively. In exposure assessment results, selection of two upper chambers was the lowest. In resolution assessment results, image of two upper chambers had the second high spatial frequency at sensitivity at 625(High) was 1.343 lp/mm. RMS value of image selecting two upper chambers was low secondly. SNR, CNR, MSR were the high value secondly. As the sensitivity was increased, radiation dose was decreased but better image could be obtained on image quality. In order to obtain the best medical images while minimizing the dose, usage of two upper ion chambers is considered to be clinically useful at sensitivity 625(High).

• The Journal of the Acoustical Society of Korea
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• v.41 no.5
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• pp.507-517
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• 2022

The PhotoAcoustic Microscopy (PAM) has been proved to be a useful tool for biological and medical applications due to its high spatial and contrast resolution. PAM is based on transmission of laser pulses and reception of PA signals. Since the strength of PA signals is generally low, not only are high-performance optical and acoustic modules required, but high-performance electronics for imaging are also particularly needed for high-quality PAM imaging. Most PAM systems are implemented with a combination of several pieces of equipment commercially available to receive, amplify, enhance, and digitize PA signals. To this end, PAM systems are inevitably bulky and not optimal because general purpose equipment is used. This paper reports a PA signal receiving system recently developed to attain the capability of improved Signal to Noise Ratio (SNR) and Contrast to Noise Ratio (CNR) of PAM images; the main module of this system is a low noise, wideband signal receiver that consists of two low-noise amplifiers, two variable gain amplifiers, analog filters, an Analog to Digital Converter (ADC), and control logic. From phantom imaging experiments, it was found that the developed system can improve SNR by 6.7 dB and CNR by 3 dB, compared to a combination of several pieces of commercially available equipment.

• Journal of the Korean Society of Radiology
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• v.15 no.6
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• pp.927-933
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• 2021

The purpose of this study was to compare and analyze the differences in scan time, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) in the third lumbar vertebral region including the back fat, spinal cord, and cerebrospinal fluid using the mDixon, T2 TSE, and T2 spectral pre-saturation with inversion-recovery (SPIR) techniques. With the factors affecting the SNR fixed, the lumbar sagittal plane images of 30 adults were compared on mDixon, T2 TSE, and T2 SPIR imaging tests. The test times for mDixon, T2 TSE, and T2 SPIR were 115 seconds, 60 seconds, and 60 seconds, respectively. The mDixon T2 images showed higher SNR than the T2 TSE images at the third lumbar vertebral region (p<0.05), lower SNR in the back fat and cerebrospinal fluid (p<0.05) areas, and comparable SNR in the spinal cord (p>0.05). The CNR between the third lumbar vertebral area and back fat was higher in the mDixon T2 images, and the CNR of the cerebrospinal fluid and spinal cord images was higher in the T2 TSE images (p<0.05). The mDixon T2 FS images CNR was lower for the 3rd lumbar vertebral body region and back fat than the T2 SPIR images, and higher for the spinal cord and cerebrospinal fluid images (p<0.05). The CNR between the third lumbar body and back fat areas was higher in the mDixon T2 FS images (p<0.05), and there was no difference in the CNR in the images of the cerebrospinal fluid and the spinal cord (p>0.05). It is difficult to determine whether the mDixon technique is superior to the conventional T2 TSE and T2 SPIR techniques in terms of test time, SNR, and CNR. This study was confined to patients with simple lower back pain and was limited by controlled experimental conditions. Studies using clinically applied protocols are warranted in the future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.9
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• pp.4429-4436
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• 2013

Measurements of CNR(Contrast to Noise Ratio) and SNR(Signal to Noise Ratio) of T-spine breathing technique (TBT) using spontaneous breathing and T-spine exhalation technique (TET) with full exhalation were carried out, and with which the more appropriate method was suggested. Both TBT and TET were examined in a sample of fifty-three patients who visit to our hospital for spinal disease from June 2012 to November 2012. All images were evaluated with CNR measured from the differences between the mean pixels and contrast density as setting ROI of spinous process, pedicle, vertebral body, intervertebral foramen, and intervertebral disk using Image J. SNR was measured with the mean pixels and the standard deviation as setting ROI of vertebral body using Image J. In CNR comparison and SNR comparison of TET and TBT, TBT was indicated as excellent in ROI of pedicle, vertebral body, intervertebral foramen and intervertebral disk, and statistical analysis were significant(p<.01). As TBT indicated excellent images compared to the existing T-spine lateral radiography, T-spine lateral radiography would be reestablished and significant as applying to various medical institutions.