• Journal of radiological science and technology
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• v.45 no.2
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• pp.103-109
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• 2022

To maintain improved image quality in mammography, the quality control process is performed using the ACR (American college of radiology) phantom. In addition, many studied were performed by fabricating the customized breast phantom to provide more information in mammography. Thus, the purpose of this study was to evaluate the image quality by designing the modified ACR phantoms. The five modified acrlylic ACR phantoms were designed by considering insert position and phantom thickness. The phantoms were consisted of 4.5, 3.0, and 1.5 cm in terms of phantom thickness, and 3.0, 2.0, and 0.5 cm in terms of insert position, respectively. The acquired images were evaluated by PSNR (peak signal to noise ratio), RMSE (root mean square error), CC (correlation coefficient), CNR (contrast to noise ratio), and COV (coefficient of variation). Based on the similarity analysis, the result is suitable between conventional and new designed phantoms. In addition, the CNR and COV results in terms of insert position showed that image quality for 0.5 cm was 2.3 and 27.4% improved compared with 2 and 3 cm, respectively. According to phantom thickness results, the CNR result for 1.5 cm and COV result for 4.5 cm were 50.1 and 62.7% improved compared with that those conditions. In conclusion, we confirmed that the image quality depends on the breast size and thickness through modified ACR phantom study.

• The Journal of Korean Society for Radiation Therapy
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• v.35
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• pp.41-51
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• 2023

Purpose: This study compares and analyzes the image quality of 3D-CBCT(Cone Beam Computed-Tomography) and Gated CBCT according to baseline changes during SBRT(Stereotactic Body RadioTherapy) in lung cancer patients to find a useful CBCT method for correcting movement due to breathing Materials and methods : Insert a solid tumor material with a diameter of 3 cm into the QUASAR^TM phantom. 4-Dimentional Computed-Tomography(4DCT) images were taken with a speed of the phantom at period 3 sec and a maximum amplitude of 20 mm. Using the contouring menu of the computerized treatment planning system Eclipse^TM Gross Tumor Volume was outlined on solid tumor material. Set-up the same as when acquiring a 4DCT image using Truebeam STx^TM, breathing patterns with baseline changes of 1 mm, 3 mm, and 5 mm were input into the phantom to obtain 3D-CBCT (Spotlight, Full) and Gated-CBCT (Spotlight, Full) images five times repeatedly. The acquired images were compared with the Signal-to-Noise Ratio(SNR), Contrast-to-Noise Ratio(CNR), Tumor Volume Length, and Motion Blurring Ratio(MBR) based on the 4DCT image. Results: The average Signal-to-Noise Ratio, Contrast-to-Noise Ratio, Tumor Volume Length and Motion Blurring Ratio of Spotlight Gated CBCT images were 13.30±0.10%, 7.78±0.16%, 3.55±0.17%, 1.18±0.06%. As a result, Spotlight Gated-CBCT images according to baseline change showed better values than Spotligtht 3D-CBCT images. Also, the average Signal-to-Noise Ratio, Contrast-to-Noise Ratio, Tumor Volume Length and Motion Blurring Ratio of Full Gated CBCT images were 12.80±0.11%, 7.60±0.11%, 3.54±0.16%, 1.18±0.05%. As a result Full GatedCBCT images according to baseline change showed better values than Full 3D-CBCT images. Conclusion : Compared to 3D-CBCT images, Gated-CBCT images had better image quality according to the baseline change, and the effect of Motion Blurring Artifacts caused by breathing was small. Therefore, it is considered useful to image guided using Gated-CBCT when a baseline change occurs due to difficulty in regular breathing during SBRT that exposes high doses in a short period of time

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.9
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• pp.4313-4319
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• 2013

The purpose of our study is to shorten the scanning time and minimize the inconveniences of the patients in acquisition of the black blood images using the signal void effect in the fast spin echo technique while keeping the diagnostic value of the test. Thirty-two consecutive patients who underwent black blood MR imaging were examed with additional double inversion recovery (DIR) sequence and the conventional fast spin echo (FSE) sequence. Signal to Noise Ratio (SNR) and Contrast to Noise Ratio (CNR) of the internal carotid arteries' lumen were compared in T1 and T2 weighted images to determine whether there are differences between the two techniques for depiction of the signal void effect inside the vessel wall. The FSE images showed lower SNR values than the DIR images in both of the T1 and T2 weighted images (11.49% and 13.66% respectively). While the CNR values were higher in the FSE images than in the DIR images in both of the T1 and T2 weighted images (8.69% and 7.55% respectively).There was no significant difference between the two techniques for either of the SNR or CNR (p>0.05, p>0.05 respectively). The DIR and the FSE images demonstrated almost identical imaging patterns. Therefore, it is anticipated that the use of FSE technique in acquisition of the black blood imaging could reduce the inconveniences of the patients during the scanning and minimize exam time while keeping the diagnostic value of the test.

• Journal of radiological science and technology
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• v.46 no.6
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• pp.485-491
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• 2023

As an auxiliary tool for fixing the patient's posture when taking an X-ray, sponges with high radiolucencies are laminated in various thicknesses. This study aimed to evaluate the usefulness of an auxiliary tool for hand oblique projection X-ray by manufacturing it with a uniform thickness by 3D printing and comparing it with existing sponge tools. In the auxiliary tool, radiolucency was measured at the stairs where each finger was located, and pixel information values were compared in the digital imaging and communications in medicine(DICOM) image. Contrast to noise ratio(CNR) and signal to noise ratio(SNR) were compared by shooting the hand phantom and the auxiliary tool together. As the thickness of the sponge tool increased, radiolucency decreased by 15.52% and pixel information value increased by 20.61%. The transmittance of the 3D printing tool increased by 0.82%, and the pixel information value differed by 5.66%. CNR and SNR increased by 20.03% and 22.42% in 3D printing compared to existing sponge tools. while taking hand oblique projection, maintaining the thickness of the auxiliary tool uniformly through 3D printing maintains high radiolucency and minimal impact on medical images, and increases CNR and SNR, making it useful as an auxiliary tool for taking hand oblique projection.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.5682-5688
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• 2013

The purpose of this study is to maximize diagnositc usefulness with increasing signal to noise ratio(SNR) and contrast to noise ratio(CNR) by using a 1mmol/mL gadolinium contrast agent. From January 2012 to June 2013 fourty-seven patients were underwent the MRI scanning to investigate the contrast difference in gadolinium content. Twenty of the patients were injencted the commercial contrast agent containing 0.5mmol/mL gadolinium and the rest of them were injected the new contrast agent containing 1mmol/mL gadolinium called gadobutrol. We measured and evaluated each SNR and CNR of the hip joint space, iliopsoas muscle and femoral head. As a result, using the 1mmol/mL gadolinium contrast agent had the higher SNR results than using the 0.5mmol/mL agent(27% in the hip joint, 30.01% in the femoral head). Also CNR using the 1mmol/mL gadolinium agent was proved to be higher than that of using 0.5mmol/mL agent(28.31% in the ilopsoas muscle and 26.74% in the femoral head). Therefore, the contrast agent containing more gadolinium like 1mmol/mL used in this study is more effective to shorten T1 relaxation time, so it increases the signal intensity and CNR and furthermore maximizes diagnostic value. This study reports the usefulness of the 1mmol/mL contrast agent in the contrast-enhanced magnetic resonance hip arthrography for the first. Therefore, it can be considered to have an meaningful academic value as showing the method for increasing the diagnostic usefulness by using the 1mmol/mL contrast agent.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.04a
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• pp.369-372
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• 2012

대사성 골 질환인 골다공증(Osteoporosis)의 조기 진단을 위한 골 밀도를 측정하는 방법이 최근 연구되고 있다. 골 밀도 영상은 이중 에너지 X 선 흡수법에 의해 측정되는데, 영상에 존재하는 잡음은 뼈 영역 추출과 골 밀도 계산에 어려움을 주고 있다. 따라서 본 논문에서는 최근 신호처리 분야에서 폭넓게 사용되고 있는 sparse 표현을 도입하여 X 선 영상의 잡음을 제거하는 방법을 제안한다. 실험을 통해 제안한 잡음 제거 방법의 결과가 기존의 방법에 비해 개선됨을 MSR(Mean to Standard deviation Ratio)과 CNR(Contrast to Noise Ratio)을 통해 확인하였다.

• Nuclear Engineering and Technology
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• v.52 no.10
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• pp.2328-2333
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• 2020

The filter technique was applied to noise images, as noise is the significant factor that cause poor image quality due to lower photon counting. The purpose of this study is to confirm that image quality can be improved using the median modified Wiener filter (MMWF) technique; this is achieved via a National Electrical Manufacturers Association International Electrotechnical Commission body phantom with four large spheres that are filled with the ^99mTc radioisotope when evaluating the image quality. Conventional filters such as Wiener, Gaussian, and median filters were designed, and signal to noise ratio, coefficient of variation, and contrast to noise ratio were used as the evaluation parameters. The improvement in the image quality was in the following order, from the least to the highest improvement, in all cases: Wiener filter, Gaussian filter, median filter, and the MMWF technique. The results show that the image quality was improved from 20.6 to 65.5%, 7.4-40.3%, and 12.7-44.7% for the SNR, COV, and CNR values, respectively, when using the MMWF technique, compared with the use of conventional filters. In conclusion, our results demonstrated that the MMWF technique is useful for reducing the noise distribution in gamma camera images.

• Investigative Magnetic Resonance Imaging
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• v.13 no.2
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• pp.161-170
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• 2009

Purpose : A parallel imaging method provides us to improve temporal resolution to obtain three-dimensional (3D) MR images. The objective of this study was to optimize three 3D MRI techniques by adjusting 2D SESNE factors of the parallel imaging method in phantom and human brain. Materials and Methods : With a 3 Tesla MRI system and an 8-channel phase-array sensitivity-encoding (SENSE) coil, three 3D MRI techniques of 3D T1-weighted imaging (3D T1WI), 3D T2-weighted imaging (3D T2WI) and 3D fluid attenuated inversion recovery (3D FLAIR) imaging were optimized with adjusting SESNE factors in a water phantom and three human brains. The 2D SENSE factor was applied on the phase-encoding and the slice-encoding directions. Signal-to-noise ratio(SNR), percent signal reduction rate(%R), and contrast-to-noise ratio(CNR) were calculated by using signal intensities obtained in specific regions-of-interest (ROI). Results : In the phantom study, SENSE factor = 3 was provided in 0.2% reduction of signals against without using SENSE with imaging within 5 minutes for 3D T1WI. SENSE factor = 2 was provided in 0.98% signal reduction against without using SENSE with imaging within 5 minutes for 3D T2WI. SENSE factor = 4 was provided in 0.2% signal reduction against without using SENSE with imaging around 6 minutes for 3D FLAIR. In the human brain study, SNR and CNR were higher with SENSE factors = 3 than 4 for all three imaging techniques. Conclusion : This study was performed to optimize 2D SENSE factors in the three 3D MRI techniques that can be scanned in clinical time limitations with minimizing SNR reductions. Without compromising SNR and CNR, the optimum 2D SENSE factors were 3 and 4, yielding the scan time of about 5 to 6 minutes. Further studies are necessary to optimize 3D MRI techniques in other areas in human body.

• Journal of the Korean Society of Radiology
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• v.17 no.7
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• pp.1025-1031
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• 2023

We aimed to evaluate the radiation dose and image quality by changing the Scout view voltage in low-dose chest CT (LDCT) and applying scan parameters such as AEC (auto exposure control) and ASIR (adaptive statistical iterative reconstruction) to find the optimal protocol. Scout view voltage was varied at 80, 100, 120, 140 kV and after measuring the dose 5 times using the existing low-dose chest CT protocol, the appropriate kV was selected for the study using the Dose report provided by the equipment. After taking a basic LDCT shot at 120 kV, 30 mAs, ASIR 50% was applied to this condition. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were assessed by measuring Background noise (B/N). For dose comparison, CTDI_vol and DLP provided by the equipment were compared and analyzed using the formulas. The results indicated that the protocol of scout 140 + LDCT + ASIR 50 + AEC reduced radiation exposure and improved image quality compared to traditional LDCT, providing an optimal protocol. As demonstrated in the experiment, LDCT screenings for asymptomatic normal individuals are crucial, as they involve concerns over excessive radiation exposure per examination. Therefore, applying appropriate parameters is important, and it is expected to contribute positively to the public health in future LDCT based health screenings.

• Journal of the Korean Society of Radiology
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• v.13 no.2
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• pp.217-225
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• 2019

The purpose of this study was to quantitate signal to noise ratio and contrast to noise ratio of the portal vein using CT and 3.0T MRI and to investigate the optimal imaging device. Twenty patients who inspective CT and 3.0T MRI between February 2018 and April 2018 were randomly assigned to receive data from the picture archiving communication system. The SNR and CNR values were evaluated by measuring the mean and standard deviation of the region of interest of the four regions of the portal vein (the main portal vein, the right vein, the left vein, and the middle vein). The results showed that SNR was 9.180.72 in the right context, 9.410.84 in the left context, 9.540.59 in the middle context, 9.550.75 in the order context, and 22.292.03 in the right context and 25.893 in the 3.0T MRI. 19, median context: 24.392.87, and order Mac: 26.642.30 (p<0.05). CNR was 3.790.68 in the CT context, 3.740.65 in the left context, 3.710.39 in the middle context, 3.790.68 in the order context, 9.490.65 in the right context, and 11.0001.90 in the 3.0T MRI, Intermediate context: 12.701.75, order Mac: 10.010.98, 3.0T MRI was higher than CT (p<0.05). In conclusion, SNR and CNR values were higher in the 3.0T MRI than CT in the 4 portal regions. Therefore, 3.0T MRI using non-ionizing radiation was the most superior imaging equipment than CT.