Adaptive Statistical Iterative Reconstruction 기법의 적용에 따른 Computed Tomography 영상의 화질과 선량 연구

박건진(Kun Jin Park),방성호(Sung Ho Bang),김문찬(Moon Chan Kim),한동균(Dong Kyoon Han) 대한CT영상기술학회 2010 대한CT영상기술학회지 Vol.12 No.1

Purpose Recently many studies had been applied to minimize radiation exposure while also obtaining suitable image quality for diagnosis. This study was focused on the evaluation of image quality and dose of CT image which were applied with adaptive statistical iterative reconstruction(ASIR) to examine the usefulness of image diagnosis. Materials and methods CT scans were performed with a 64-slice MIDCT scanner(GE LightSpeed VCT XTe, waukesha, Wisconsin, USA). CTDI measurement was used for comparing doses while the ACR Phantom was used for image quality comparison. The ASIR was used for image reconstruction which create a noise map based on the filtered backprojection(FBP) and organized a statistical model and blends it with appropriately original FBP image. For image quality comparison in phantom study, CTDIVOL 14.76 mGy for non-ASIR was applied and evaluations were clone by analyzing items such as noise level, olv-contrast and high-contrast resolution. In patient study, test were clone by CTDIVOL 9.45 mGy (standard chest CT dose) and 0.90 mGy, 0.45 mGy, and 0.36 mGy(low dose CT) were delivered with standard and bone kernel. Results In phantom study showed that the upward values of spatial resolution were generally similar among kernels and low-resolution kernels showed excellence of contrast to noise(CNR) above 1.0 compared to high-resolution kernels in ASIR 50 and showed improved CNR even though decreased of dose 40% above. With same Parameters noise level(NL) showed 2% in FBP image, 1.5% in ASIR 30% above, and 1% or less in ASIR 100%. Differentiating by the naked eye was difficult, but the differences between each kernel of ASIR were recognized by measuring resolution and noise by quantitative analysis. The effective dose of the low-dose chest examination held as a patient study was only 0.3 mSv or less. It showed reduction of 90% compared to the standard dose, and similar image quality was maintained by applying ASIR 30~60%. However, high-resolution kernels With high ASIR showed a severe level of noise including streak artifacts. Conclusion CT image reorganization using ASIR is considered to be a useful dose reducing method while maintaining the image quality, when comparing with the existing filtered back-projection (FBP) reorganized images.

Adenosine triphosphate(ATP)를 이용한 운동부하 cardiac CT angiography 검사의 특성과 유용성

박건진(Kun Jin Park),김완역(Wan Yuk Kim),김문찬(Moon Chan Kim),한동균(Dong Kyoon Han) 대한전산화단층기술학회 2007 대한CT영상기술학회지 Vol.9 No.1

Purpose In the sphere of noninvasive CT (Computed Tomography), the perfusion evaluation of the left ventricle has been recently performed through the technical advance of MDCT (Multi-Detector Computed Tormgraphy) and the application of ECG gating. In this study, cardiac stress CT was performed by using ATP (Adenosine Triphosphate : DENOSIN??) on purpose to evaluate cardiac diseases through cardiac rest CT and myocardial image analysis, and to analyze the characteristics of cardiac stress CT and its usability. Materials and Methods The 33 patients, who underwent ATP cardiac CT from July 1, 2006 until January 31, 2007 in this hospital, were subject to this study and the medical data of 33 cases, collected from them, were applied to the research. ATP of 0.84mg/kg was slowly administered by using the syringe pump for 6 minutes. A stress view was taken after 5 minutes, and a rest view was taken 15 minutes after ATP was ceased. As regards image analysis, ROI (Region of Interest) was measured at the 4 segments in the ventricle, and PD (Physical Density) analysis and qualitative analysis were performed. Results 1. The average density of myocardial lesion was different, about between 50 and 60mg/cm³, as compared with those of other lesions. 2. The result of rest investigation was compared with the cases where myocardial ischemic lesion is observed in stress among the patients who showed the perfusion defects of myocardium. In result, the sensitivity to cardiovascular diseases was higher in stress investigation as compared with that of rest investigation. 3. Myocardial segments were mieasured by ROI analysis, with the consequence that the mild stenosis of the coronary artery could be diagnosed. Conclusion It is considered that the ATP-based cardiac stress CT is useful to compare evaluate the myocardium in cardiac excitement with stabilization, and to detect the coronary artery stenosis latent in patients. In addition, it is expected to research the characteristics of investigations through ROI analysis and image analysis, and to extend the existing diagnostic range in cardiac examination.

재구성 알고리즘 변화에 따른 CT 영상의 화질 평가

한동균,박건진,고신관,Han, Dong-Kyoon,Park, Kun-Jin,Ko, Shin-Kwan 대한디지털의료영상학회 2010 대한디지털의료영상학회논문지 Vol.12 No.2

In this study, the correlation among the changes of Modulation Transfer Function(MTF) in the noise and high-contrast resolution and the change of Contrast to noise ratio(CNR) in the low-contrast resolution will be examined to investigate the estimation of image quality according to the type of algorithms. The image data obtained by scanning American Association of Physicists in Medicine(AAPM) phantom was applied to each algorithm and the exposure condition of 120 kVp, 250 mAs, and then the CT number and noise were measured. The MTF curved line of the high-contrast resolution was calculated with Point Spread Function(PSF) by using the analysis program by Philips, resulting in 0.5 MTF, 0.1 MTF and 0.02 MTF respectively. The low-contrast resolution was calculated with CNR and the uniformity was measured to each algorithm. Since the measurement value for the uniformity of the equipment was below ${\pm}$ 5 HU, which is the criterion figure, it was found to belong to the normal range. As the algorithm got closer from soft to edge, the standard deviation of CT number increased, which indicates that the noise increased as well. As for MTF, 0.5 MTF, 0.1 MTF and 0.02 MTF were all sharp algorithms, and as the algorithm got closer from soft to edge, it was possible to distinguish more clearly with the naked eye. On the other hand, CNR gradually decreased, because the difference between the contrast hole CT number and the acrylic CT number was the same while the noise of hole increased.

관상동맥 협착 진단을 위한 workstation별 QCA값의 비교 평가

김완역(Wan Yuk Kim),박건진(Kun Jin Park),변정인(Jung In Byun) 대한전산화단층기술학회 2007 대한CT영상기술학회지 Vol.9 No.1

Purpose As 64 Multi-Detector Computed Tomography systems were recently introduced and software has been variously developed, coronary CT angiography has been clinically come into notice. The patients, diagnosed with coronary arteriostenosis due to thrombi, were subject to this study. In this study, Quantitative Coronary Analysis value was comparatively analyzed by using the workstations produced by 4 companies respectively. Materials and Methods The 20 patients who showed the stenos is of the left anterior descending artery due to thrombi, among the patients, who underwent coronary CT angiography from November 2006 until January 2007, were subject to this study. The CT angiography was performed by using Toshiba Aquilion 64 under the condition of 120kVp, 400mA, 0.4sec tube rotation time. In result, the images of 75, 35, 45 and 90% with the sectional thickness of 0.5mm/0.4mm were taken and were transmitted to the workstation for image reconstruction. Extended brilliance workstation, Advantage workstation, Vitrea workstation, and TeraRecon workstation were used to measuring instruments, and QCA value, i.e., the stenos is degree of left anterior descending artery, was measured. Results 1. With regard to the QCA value based on area value, TeraRecon workstation showed the highest value but the value of PDW was lowest. 2. With regard to the QCA value based on average diameter value, the value of Vitrea workstation was highest but ADW also showed the lowest value. Conclusion QCA values were measured by using the workstations produced by 4 companies respectively; with the consequence that the values become different as to company and TeraRecon workstation and Vitrea workstation did not show conspicuous differences in case the vascular diameter is over 3mm. However, EBW and ADW showed remarkable differences in case the vascular diameter is less than 3mm. In case the vascular area is over 6mm², TeraRecon workstation and Vitrea workstation did not significant differences. When compared to QCA, the ability of workstation to quantitatively assess coronaiy artery diameters and coronary artery stenases is insufficient for clinical purposes

Coronary CT Angiography에서 Cardio ImageXact

김부환(Boo Hwan Kim),남윤철(Yoon Chul Nam),박건진(Kun Jin Park),김완역(Wan Yuk Kim),김문찬(Moon Chan Kim) 대한CT영상기술학회 2008 대한CT영상기술학회지 Vol.10 No.1

Purpose This research is that evaluate quality of reconstruction by Heart rate change in coronary arteries building CT examination about coronary artery disease patient who is being on the increase gradually and improve quality of reconstruction by searching for Cardiac reconstruction phase of most suitable in Heart rate that do using Cardio ImageXact that is TOSHIBA company’ s software. Materials and Methods From May, 2006 to July, 2007, Coronary CT Angiography did to 43 outpatients who examine and patient who undergo Coronary Artery Bypass Graft(CABG) surgical operation excepted. Patient does NPO during before examination and vital(BP, Heart rate) check and do 1/2T and carry on the head Metoprolol in case Heart rate more than 65, and in case is more than 75, effect conducted examination after 1 hour that is time that become maximum efficiency after did to take 1T(100mg). Reconstructed data using Cardio ImageXact that is TOSHIBA raw data reconstruction software by Auto(Best)phase, % method, ms(milli-second) method cardiac reconstruction raw data. Analysis method use Cardio ImageXact software acquires data as much as 0~99% to 1% space and 10ms space and R-R interval space to 10ms space in section of 2 level(aortic valve, mitral valve level)in raw data after examination and quality selects the best cardiac phase and acquire volume data in 3 method. Corona1y artery’ s quality in 3 cardiac recon mode analyzed comparison. Results Compared point through vessel analysis of target patient total 43 people on above 3 mode to use TOSHIBA company’ s cardiac phase recon software. 1. When Heart rate is 50~59 Average point becomes difference in segment No.2 and No.3, No.6, No.7 in 3 recon mode and difference did not become in other segment. 2. When Heart rate is 60~69 Could know that could acquire good image seeing that ms method acquires near point in 1 point in segment excepting segment No.10. 3. When Heart rate is 70~79 It is seldom difference of m.5 mode with % mode in each segment different 3 recon mode, showed near differentia in 1 point more with Auto(Best)phase mode, and % mode and ms mode could know that difference of average point is not great quality difference of image after recon in 0.1 point interior and exterior. 4. When Heart rate is over 80 Each segment different 3 recon mode could know in segment excepting segment No.9 that ms mode could get better image showing near point 1 point than Auto(Best) mode with % mode. Each segment different acquired point could make image that ms mode is better receiving near point in head of a family 1 point in Auto(Best) mode and % mode, ms mode to be 3 recon mode in each heart rate different each segment and % mode was some difference than ms mode, but did not show large difference. However, Auto(Best)recon mode to acquire good image missing near point in 1 point than above 2 mode difficulty know can. Also, Heart rate 3 recon mode did not show difference greatly in 50~59 but Heart rate is higher more than 60~69, 70~79, 80 difference of point that acquire could appear greatly and know qualitative difference of image. Conclusion By Auto(Best) and % mode or ms mode strongly in Heart rate that do stable very cardiac phase image that may not do reconstruction get. But, 75% and 45% cardiac phase are thought that this research is value more to supplement this to could not have gotten good image, and could not have good image in Auto(Best)phase usually in heart rate’ s case that do unstable. Reduce patient’ s re-procedure having gotten good image through this research, and expect to give large help diagnostic and treatment of heart vessel disease by supplying correct diagnostic information.