• The Korean Journal of Nuclear Medicine Technology
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• v.27 no.2
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• pp.99-109
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• 2023

Purpose: CT scan makes up for the weak point of the nuclear medicine image having a low resolution and also were used for attenuation correction on image reconstruction. Recently, many studies try to make use of CT images additionally, one of them is to measure the bone mineral density(BMD) using Quantitative CT(QCT) software. BMD exams are performed to scan lumbar and femur with DXA(Dual-Energy X-Ray Absorptiometry) in order to diagnose bone disease such as osteopenia, osteoporosis. The purpose of this study is to identify the usefulness of QCT_BMD analyzed with low dose CT images on L-spine Bone SPECT/CT comparing with DXA_BMD. Materials and Methods: Fifty five women over 50 years old (mean 66.4 ± 9.1) who took the both examinations(L-spine Bone SPECT/CT with SIEMENS Intevo 16 and DXA scan with GE Lunar prodigy advance) within 90 days from April 2017 to July 2022, BMD, T-score and disease classification were analyzed. Three-dimensional BMD was analyzed with low dose CT images acquired on L-spine Bone SPECT/CT scan on Mindways QCT PRO^TM software and two-dimensional BMD was analyzed on DXA scan. Basically, Lumbar 1-4 were analyzed and the patients who has lesion or spine implants on L-spine were excluded for this study. Pearson's correlation analysis was performed in BMD and T-score, chi-square test was performed in disease classification between QCT and DXA. Results: On 55 patients, the minimum of QCT_BMD was 18.10, maximum was 166.50, average was 82.71 ± 31.5 mg/cm³. And the minimum of DXA-BMD was 0.540, maximum was 1.302, average was 0.902 ± 0.201 g/cm², respectively. The result shows a strong statistical correlation between QCT_BMD and DXA_BMD(p<0.001, r=0.76). The minimum of QCT_T-score was -5.7, maximum was -0.1, average was -3.2 ± 1.3 and the minimum of DXA_T-score was -5.0, maximum was 1.7, average was -2.0 ± 1.3, respectively. The result shows a statistical correlation between QCT T-score and DXA T-score (p<0.001, r=0.66). On the disease classification, normal was 5, osteopenia was 25, osteoporosis was 25 in QCT and normal was 10, osteopenia was 25, osteoporosis was 20 in DXA. There was under-estimation of bone decrease relatively on DXA than QCT, but there was no significant differences statistically by chi-square test between QCT and DXA. Conclusion: Through this study, we could identify that the QCT measurement with low dose CT images QCT from L-Spine Bone SPECT/CT was reliable because of a strong statistical correlation between QCT_BMD and DXA_BMD. Bone SPECT/CT scan can provide three-dimensional information also BMD measurement with CT images. In the future, rather than various exams such as CT, BMD, Bone scan are performed, it will be possible to provide multipurpose information via only SPECT/CT scan. In addition, it will be very helpful clinically in the sense that we can provide a diagnosis of potential osteoporosis, especially in middle-aged patients.

• The Journal of the Korean bone and joint tumor society
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• v.1 no.1
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• pp.7-16
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• 1995

In countries where confucianism is popular, it is extremely hard to get fresh cadaver bone for allograft. Therefore in Korea, the reimplantation of resected autoclaved autogenous bone segments has been increasingly performed for limb reconstruction of extremities with malignancies. To preserve the bone morphogenetic protein and mechanical strength of heated bone, many studies have reported that pasteurization of bone is far better than autoclaving over $100^{\circ}C$. Based on this assumption, replacement with a pasteurized autogenous bone graft after resection of a malignant bone tumor was deemed feasible for reconstruction. However, little is known about how high a temperature and how much time for pasteurization is needed to make tumors completely necrotic and to maintain the mechanical strength of bone. Consequantly, experimental studies were carried out to test heat conductivity of human bone and torsional strength of porcine tibia after pasteurization. First, two pairs of human proximal tibia and distal femur were used. We used T-type thermocoples to check core temperature of the bone and a computerized data acquisition system to record results. Without reaming of the medullary cavity, in a $60^{\circ}C$-thermostatic saline tub, it took 32 minutes and 50 seconds to raise the core temperature of human proximal tibia from $20^{\circ}C$ to $58^{\circ}C$, and 30 minutes for distal femur. In a $80^{\circ}C$ saline tub, it took 12 minutes and 50 seconds for proximal tibia, and 11 minutes and 10 seconds for distal femur. In contrast, using porcine tibia whose cortical thickness is similar to that of human tibia, after reaming of the medullary canal, it took less than 3 minutes and 30 seconds in a $60^{\circ}C$ saline tub, less than 1 minute and 45 seconds in a $70^{\circ}C$ tub, and less than 1 minute in a $80^{\circ}C$ tub to elevate core temperature from $20^{\circ}C$ to $58^{\circ}C$. Second, based on data of the heat conductivity test, we compared the torsional strength before and after pasteurization. Twenty matched pairs of porcine tibia were used, The left one was used as a non-heated control group and the right one as a pasteurized experimental group. Wighout reaming of the medullary cavity, there was no statistical difference in torsional strength between the pasteurization of the $60^{\circ}C$-35minute and of $80^{\circ}C$-15minute. With reaming, we also found no statistical difference among pasteurization of $60^{\circ}C$-15 minute, of $70^{\circ}C$-15 minute, and of $80^{\circ}C$-15 minute groups. In conclusion, reaming of the medullary canal is very helpful in saving pasteurization time. And, in a $60^{\circ}C$ saline tub, no significant weakness in torsional strength occurs with pasteurization of the bone for up to 35 minutes. Also no significant weakness in torsional strength occurs with an exposure of 15 minutes to the $80^{\circ}C$ saline tub.

• The Korean Journal of Nuclear Medicine Technology
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• v.19 no.2
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• pp.55-62
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• 2015

Purpose Various methods for reducing radiation exposure have been continuously being developed. The aim of this study is to evaluate effectiveness of dose reduction, image quality and PET SUV changes by applying combination of automatic exposure dose(AEC), automated dose-optimized selection of X-ray tube voltage(CAREkV) and sinogram affirmed iterative reconstruction(SAFIRE) which can be controled by user. Materials and Methods Torso, AAPM CT performance and IEC body phantom images were acquired using biograph mCT64, (Siemens, Germany) PET/CT scanner. Standard CT condition was 120 kV, 40 mAs. Radiation exposure and noise were evaluated by applying AEC, CAREkV(120 kV, 40 mAs) and SAFIRE(120 kV, 25 mAs) with torso phantom compare to standard CT condition. And torso, AAPM and IEC phantom images were acquired with combination of 3 methods in condition of 120 kV, 25 mAs to evaluate radiation exposure, noise, spatial resolution and SUV changes. Results When applying AEC, CTDIvol and DLP were decreased by 50.52% and 50.62% compare to images which is not applying AEC. mAs was increased by 61.5% to compensate image quality according to decreasing 20 kV when applying CAREkV. However, CTDIvol and DLP were decreased by 6.2% and 5.5%. When reference mAs was the lower and strength was the higher, reduction of radiation exposure rate was the bigger. Mean SD and DLP were decreased by 2.2% and 38% when applying SAFIRE even though mAs was decreased by 37.5%(from 40 mAs to 25 mAs). Combination of 3 methods test, SD decreased by 5.17% and there was no significant differences in spatial resolution. And mean SD and DLP were decreased by 6.7% and 36.9% compare to 120 kV, 40 mAs with AEC. For SUV test, there was no statistical differences(P>0.05). Conclusion Combination of 3 methods shows dose reduction effect without degrading image quality and SUV changes. To reduce radiation exposure in PET/CT study, continuous effort is needed by optimizing various dose reduction methods.

• The Korean Journal of Nuclear Medicine Technology
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• v.21 no.2
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• pp.31-36
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• 2017

Purpose Recently, the performance of PET/CT scanner has been improved and various techniques have been developed to increase the image quality such as Sensitivity and Resolution. The purpose of this study is to evaluate the usefulness of Q.Clear (a fully convergent iterative reconstruction) technique of GE Discovery IQ equipment to enhance the image quality. Materials and Methods All scans were acquired by Discovery IQ (GE Healthcare, MI, USA). In NEMA IEC Body Phantom test, Background to Hot-sphere (10 mm, 13 mm, 17 mm, 22 mm) ratio was 1:4 and scan time was 3 minutes. The images were reconstructed by VPHDs (VUE Point High-Definition + SharpIR) and Q.Clear to evaluate each Contrast. We injected 18F-FDG 187 M㏃ to PET/SPECT Performance Phantom. And then it was scanned for 4 minutes to evaluate Resolution and Uniformity. T-test statistical analysis was performed on SUVmax of small lesions less than 2 cm in 100 clinical patients regardless of disease type. Results In the NEMA IEC Body Phantom, the Contrast was $63.6{\pm}5.7%$ (VPHDs) and $75{\pm}4.8%$ (Q.Clear). In the PET/SPECT Performance Phantom, the Resolution was 9.2 mm (VPHDs) and 7.3 mm (Q.Clear). Uniformity of Q.Clear was 10.8% better than VPHDs. T-test statistic of the clinical patients showed a significant difference of p value of 0.021. Conclusion Both the phantom test and the clinical results showed that the quality of the image was improved in Q.Clear was applied. The SUVmax was highly measured in Q.Clear and the lesions were clearly distinguished visually. Therefore Q.Clear can be useful in various aspects such as dose-reduction, patients evaluation and image analysis.

• Progress in Medical Physics
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• v.14 no.2
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• pp.131-140
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• 2003

As the importance of accuracy in measurings of 3-D anatomical structures continues to be stressed, an objective and quantitative of assessing image quality and accuracy of 3-D volume-rendered images is required. The purpose of this study was to evaluate the quantitative accuracy of 3-D rendered images obtained with MDCT, scanned at various scanning parameters (scan modes, slice thicknesses and reconstruction slice thickness). Twelve clinically significant points that play an important role for the craniofacial bone in plastic surgery and dentistry were marked on the surface of a dry human skull. The direct distances between the reference points were defined as gold standards to assess the measuring errors of 3-D images. Then, we scanned the specimen with acquisition parameters of 300 mA, In kVp, and 1.0 sec scan time in axial and helical scan modes (pitch 3:1 and 6:1) at 1,25 mm, 2.50 mm, 3.75 mm and 5.00 mm slice thicknesses. We performed 3-D visualizations and distance measurements with volumetric analysis software and statistically evaluated the quantitative accuracy of distance measurements. The accuracy of distance measurements on the 3-D images acquired with 1.25, 2.50, 3,75 and 5.00 mm slice thickness were 48%, 33%, 23%, 14%, respectively, and those of the reconstructed 1.25 mm were 53%, 41%, 43%, 36% respectively. Meanwhile, there were insignificant statistical differences (P-value<0.05) in the accuracy of the distance measurements of 3-D images reconstructed with 1.25 mm thickness. In conclusion, slice thickness, rather than scan mode, influenced the quantitative accuracy of distance measurements in 3-D rendered images with MDCT. The quantitative analysis of distance measurements may be a useful tool for evaluating the accuracy of 3-D rendered images used in diagnosis, surgical planning, and radiotherapeutic treatment.

• Journal of the Korean Orthopaedic Association
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• v.56 no.6
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• pp.498-503
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• 2021

Purpose: The aim of this study were to find ideal entry point of straight antegrade humeral intramedullary nail (SAHN) for the treatment of proximal humerus fracture in Korean and to analyze anatomical conformity using computed tomography. Materials and Methods: From May 2014 to October 2016, the study was conducted retrospectively on 74 Korean patients who had taken computed tomography on both normal and affected shoulder joint as result of shoulder injury. The mean age of the patients was 64.5 years (range, 22-95 years). Radiologic evaluation was done using multiplanar reconstruction technique of the computer tomography on normal proximal humerus. We located ideal entry point of SAHN as the point where humerus intramedullary center axis and humeral head meet. Distance between the entry point and local anatomical landmark was measured. We defined the critical distance as the distance between entry point and the most medial point of the supraspinatus attachment site. For adequate fixation and avoidance of injury to rotator cuff, critical distance should be over 8 mm according to Euler, and we defined the critical type when it is less than 8 mm. Critical distance, sex, age, height, body weight, body mass index was evaluated for the statistical significance. Results: The ideal entry point was as follows: the mean anteroposterior distance, the sagittal distance to the lateral margin of bicipital groove, was 11.5 mm and the mean mediolateral distance, the coronal distance to the lateral margin of grater tuberosity, was 20.5 mm. The mean critical distance, distance from the entry point to the just medial to insertion of the supraspinatus tendon, was 8.0 mm. Critical type with critical distance less than 8 mm was found in 41 in 74 patients (55.4%). Conclusion: The ideal entry point of SAHN in Korean was located on 11.5 mm posteriorly from the lateral margin of bicipital groove and 20.5 mm medially from lateral margin of greater tuberosity. More than half of the cases were critical type. Since critical type can possibly cause rotate cuff injury during nail insertion on entry point, surgeon should consider anatomical variance before choosing surgical option.

• Imaging Science in Dentistry
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• v.36 no.1
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• pp.49-54
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• 2006

Purpose : To evaluate accuracy and reliability of program to measure facial soft tissue thickness using 3D computed tomographic images by comparing with direct measurement. Materials and Methods : One cadaver was scanned with a Helical CT with 3 mm slice thickness and 3 mm/sec table speed. The acquired data was reconstructed with 1.5 mm reconstruction interval and the images were transferred to a personal computer. The facial soft tissue thickness were measured using a program developed newly in 3D image. For direct measurement, the cadaver was cut with a bone cutter and then a ruler was placed above the cut side. The procedure was followed by taking pictures of the facial soft tissues with a high-resolution digital camera. Then the measurements were done in the photographic images and repeated for ten times. A repeated measure analysis of variance was adopted to compare and analyze the measurements resulting from the two different methods. Comparison according to the areas was analyzed by Mann-Whitney test. Results : There were no statistically significant differences between the direct measurements and those using the 3D images (p>0.05). There were statistical differences in the measurements on 17 points but all the points except 2 points showed a mean difference of 0.5 mm or less. Conclusion : The developed software program to measure the facial soft tissue thickness using 3D images was so accurate that it allows to measure facial soft tissues thickness more easily in forensic science and anthropology.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.3
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• pp.23-31
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• 2010

The increasing demands on low-power, and low-complexity video encoder have been motivating extensive research activities on distributed video coding (DVC) in which the encoder compresses frames without utilizing inter-frame statistical correlation. In DVC encoder, contrary to the conventional video encoder, an error control code compresses the video frames by representing the frames in the form of syndrome bits. In the meantime, the DVC decoder generates side information which is modeled as a noisy version of the original video frames, and a decoder of the error-control code corrects the errors in the side information with the syndrome bits. The noisy observation, i.e., the side information can be understood as the output of a virtual channel corresponding to the orignal video frames, and the conditional probability of the virtual channel model is assumed to follow a Laplacian distribution. Thus, performance improvement of DVC systems depends on performances of the error-control code and the optimal reconstruction step in the DVC decoder. In turn, the performances of two constituent blocks are directly related to a better estimation of the parameter of the correlation channel. In this paper, we propose an algorithm to estimate the parameter of the correlation channel and also a low-complexity version of the proposed algorithm. In particular, the proposed algorithm minimizes squared-error of the Laplacian probability distribution and the empirical observations. Finally, we show that the conventional algorithm can be improved by adopting a confidential window. The proposed algorithm results in PSNR gain up to 1.8 dB and 1.1 dB on Mother and Foreman video sequences, respectively.

• Journal of Korean Orthopaedic Sports Medicine
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• v.9 no.2
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• pp.91-97
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• 2010

Purpose: The purpose of this study was to evaluate the results of treatment for longitudinal meniscal tear in ACL rupture patients by clinical evaluation and $2^{nd}$ look arthroscopy. Materials and Methods: Among the patients who underwent surgery due to ACL rupture and longitudinal meniscal tear between 2002~2009, 32 patients were selected for the study. The patients were devided into three groups; group 1 had repair, group 2 had partial menisectomy due to impossible to repair, group 3 had conservative treatment due to stable meniscus. Comparative retrospective analysis was applied with KT 1000 arthrometer, Lysolm' score, Tegner activity score, IKDC subjective score, and $2^{nd}$ look arthroscopy. Results: Lysolm' score, Tegner activity score, IKDC subjective score showed no statistical difference in all three groups. KT-1000 side to side difference improved from 6.2, 6.15, 6.38 before surgery to 2.56, 2.49, 2.58 after surgery in group 1, 2, and 3, respectively. In group 1, second-look arthroscopy revealed complete healing in 12 patients, incomplete healing without any clinical symptoms in 2, and healing failure in 1. In group 2, second-look arthroscopy showed partial regeneration on margin of meniscectomy. In group 3, second-look arthroscopy revealed complete healing in 2 patients, while 4 showed incomplete healing so that have repaired. Conclusion: In the study, the outcome was better when the stable longitudinal meniscal tear on posterior horn with ACL rupture had active treatment.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.1B
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• pp.37-45
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• 2011

We studied noise influence on nonlinear chaotic system by using Logistic data series which is known as a typical nonlinear chaotic system. We regenerated Logistic data series by the method of adding noise according to noise level. And, we performed some analyses such as phase space reconstruction, correlation dimension, BDS statistics, and DVS Algorithms which are known as the methods of nonlinear deterministic or chaotic analysis. If we see the results of analysis, the characteristics of data series are gradually changed from nonlinear chaotic data series to random stochastic data series according to increasing noise level. We applied Low Pass Filter (LPF) and Kalman Filter techniques for the investigation of removing effect of the added noise to data series. Typical nonparametric method cannot distinguish nonlinear random series but the BDS statistic can distinguish the nonlinear randomness of the time series. Therefore this study used the BDS statistic which is well known as nonlinear statistical method for the investigation of randomness of time series for the effect of removing noise of data series. We found that Kalman filter is better method to remove the noise of chaotic data series even for high noise level.