• Title/Summary/Keyword: 이중 에너지 CT

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Comparison of Metal Artifact Reduction Algorithms in Patients with Hip Prostheses: Virtual Monoenergetic Images vs. Orthopedic Metal Artifact Reduction (고관절 인공치환술 환자에서 금속 인공물 감소 방법의 비교: 가상 단일에너지영상 대 금속 인공물 감소기법)

  • Hye Jin Yoo;Sung Hwan Hong;Ja-Young Choi;Hee Dong Chae
    • Journal of the Korean Society of Radiology
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    • v.83 no.6
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    • pp.1286-1297
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    • 2022
  • Purpose To assess the usefulness of various metal artifact reduction (MAR) methods in patients with hip prostheses. Materials and Methods This retrospective study included 47 consecutive patients who underwent hip arthroplasty and dual-energy CT. Conventional polyenergetic image (CI), orthopedic-MAR (OMAR), and virtual monoenergetic image (VMI, 50-200 keV) were tested for MAR. Quantitative analysis was performed in seven regions around the prostheses. Qualitative assessments included evaluation of the degree of artifacts and the presence of secondary artifacts. Results The lowest amount of image noise was observed in the O-MAR, followed by the VMI. O-MAR also showed the lowest artifact index, followed by high-keV VMI in the range of 120-200 keV (soft tissue) or 200 keV (bone). O-MAR had the highest contrast-to-noise ratio (CNR) in regions with severe hypodense artifacts, while VMI had the highest CNR in other regions, including the periprosthetic bone. On assessment of the CI of pelvic soft tissues, VMI showed a higher structural similarity than O-MAR. Upon qualitative analysis, metal artifacts were significantly reduced in O-MAR, followed by that in VMI, while secondary artifacts were the most frequently found in the O-MAR (p < 0.001). Conclusion O-MAR is the best technique for severe MAR, but it can generate secondary artifacts. VMI at high keV can be advantageous for evaluating periprosthetic bone.

Dose Characteristics of Stereotactic Radiosurgery in High Energy Linear Accelerator Proton Beam (고에너지 선형가속기에 의한 입체방사선수술의 선량특성)

  • Choi, Tae-Jin;Kim, Ok-Bae
    • Radiation Oncology Journal
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    • v.10 no.2
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    • pp.137-145
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    • 1992
  • Three-dimensional dose calculations based on CT images are fundamental to stereotactic radiosurgery for small intracranial tumor. In our stereotactic radiosurgery program, irradiations have been performed using the 6 MV photon beam of linear accelerator after stereotactic CT investigations of the target center through the beam's-eye view and the coordinates of BRW frame converted to that of radiosurgery. Also we can describe the tumor diameter and the shape in three dimensional configuration. Non-coplanar irradiation technique was developed that it consists of a combination of a moving field with a gantry angle of $140^{\circ}$, and a horizontal couch angle of $200^{\circ}C$ around the isocenter. In this radiosurgery technique, we provide the patient head setup in the base-ring holder and rotate around body axis. The total gantry moving range shows angle of 2520 degrees via two different types of gantry movement in a plane perpendicular to the axis of patient. The 3-D isodose curves overlapped to the tumor contours in screen and analytic dose profiles in calculation area were provided to calculate the thickness of $80\%$ of tumor center dose to $20\%$ of that. Furtheremore we provided the 3-D dose profiles in entire calculation plane. In this experiments, measured isodose curves in phantom irradiation have shown very similiar to that of computer generations.

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Dependence of Electronic Spectra on the Degree of Conjugation in Organocobalt(Ⅲ) Complexes (공액도에 따른 유기코발트 착화합물의 전자스펙트럼에 관한 연구)

  • Hye Kyung Seo;Chan Ah Bong;Young Ae Hwang Park
    • Journal of the Korean Chemical Society
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    • v.37 no.12
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    • pp.1047-1052
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    • 1993
  • The electronic spectra of enzyme-model organocobalt(Ⅲ) complexes containing completely or partially conjugated macrocyclic ligands were measured in various solvents to investigate the solvent effect on the charge transfer band for the axial cobalt-carbon bond by the extent of conjugation in the equatorial macrocyclic ring; completely conjugated, $CH_3CoL,\;C_6H_5CoL,\;CNCoL,\;CH_3CoL',\;CNCoL'$, partially conjugated $CH_3(py)Co(DH)_2, CH_3CoL"$, unconjugated dienes, $[CH_3Co(1,4-CT)](ClO_4)_2$, and open ring, $CH_3Co(salen)$. The position of the charge transfer band which corresponds to the cobalt-carbon bond was shifted to a shorter wavelength as the polarity of solvent increased and the transition energy $(E_T)$ had a linear relationship with solvent polarity parameter, Z-value, only in the case of completely conjugated system. However, the linear correlation between $E_T$and Z was not observed for partially conjugated and open ring systems.

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Microvascular Pulmonary Tumor Embolism Detected by Perfusion Images of Dual-Energy Computed Tomography (이중에너지 컴퓨터 단층촬영을 통해 진단된 폐의 미세혈관종양색전증)

  • Ok, Tae-Jin;Cho, Min-Soo;Jang, Sun-Joo;Park, Han-Seung;Park, Hwan-Sung;Park, Se-Jeong;Yoon, Shin-Kyo;Lee, Ho-Su;Baek, Chung-Hee;Kim, Gwang-Un;Kim, Dal-Yong;Hong, Yoon-Ki;Seo, Joon-Beom;Oh, Yeon-Mok
    • Tuberculosis and Respiratory Diseases
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    • v.72 no.1
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    • pp.63-67
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    • 2012
  • Although advances in multi-detector computed tomography (CT) technique make it possible to evaluate peripheral subsegmental pulmonary arteries, several studies have reported that small peripheral embolisms may still be missed. Recently, some reports demonstrated that dual-energy CT improved the capability to detect peripheral pulmonary embolism. We report a case of lymphoma presenting as disseminated microvascular pulmonary tumor embolism, detected by perfusion images using dual energy CT.

Multidetector Computed Tomography in Patients with Femoral Neck Fracture for Assessing Osteoporosis: Comparison with Dual Energy X-Ray Absorptiometry (대퇴골 경부 골절 환자에서 골다공증 평가를 위한 다중검출 CT의 이용: 이중에너지 X-선 흡수계측법과의 비교)

  • Hyo Jeong Lee;Ji Young Hwang
    • Journal of the Korean Society of Radiology
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    • v.82 no.1
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    • pp.173-181
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    • 2021
  • Purpose To evaluate the ability of the Hounsfield unit (HU) measurement of the femoral neck during multidetector computed tomography (MDCT) for assessing osteoporosis compared with dual-energy X-ray absorptiometry (DXA). Materials and Methods Forty-two patients with femoral neck fractures who underwent MDCT and DXA from July to December 2016 were included in this study. HU measurements were made of the cancellous portions of the normal contralateral femoral neck on MDCT. Bone mineral density (BMD) and T-scores were obtained at the femur DXA. Correlations of HU values with BMD and T-scores were analyzed using Spearman's correlation test. Results The mean BMD and T-score of the femoral neck were 0.650 g/cm2 and -2.4, respectively. The mean HU values for the normal, osteopenia, and osteoporosis groups were 131.9, 98.9, and 41.3, respectively. HU values at the femoral neck were positively correlated with BMD (r2 = 0.670; p < 0.001) and T-scores (r2 = 0.676; p < 0.001). Conclusion The HU values of the femoral neck on MDCT are significantly correlated with BMD and T-scores of femur DXA. The HU values may serve as a diagnostic tool for the screening of regional bone quality when MDCT is performed for other reasons.

Study on Oneself Developed to Apparatus Position of Measurement of BMD in the Distal Radius (자체 개발한 보조기구로 원위 요골의 골밀도 측정 자세 연구)

  • Han, Man-Seok;Song, Jae-Yong;Lee, Hyun-Kuk;Yu, Se-Jong;Kim, Yong-Kyun
    • Journal of radiological science and technology
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    • v.32 no.4
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    • pp.419-426
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    • 2009
  • Purpose : The aim of this study was to evaluate the difference of bone mineral density according to distal radius rotation and to develop the supporting tool to measure rotation angles. Materials and Methods : CT scanning and the measurement of BMD by DXA of the appropriate position of the forearm were performed on 20 males. Twenty healthy volunteers without any history of operations, anomalies, or trauma were enrolled. The CT scan was used to evaluate the cross sectional structure and the rotation angle on the horizontal plane of the distal radius. The rotational angle was measured by the m-view program on the PACS monitor. The DXA was used in 20 dried radii of cadaveric specimens in pronation and supination with five and ten degrees, respectively, including a neutral position (zero degrees) to evaluate the changes of BMD according to the rotation. Results : The mean rotation angle of the distal radius on CT was 7.4 degrees of supination in 16 cases (80%), 3.3 degrees of pronation in three cases (15%), and zero degree of neutral in one case (9%), respectively. The total average rotation angle in 20 people was 5.4 degrees of supination. In the cadaveric study, the BMD of the distal radius was different according to the rotational angles. The lowest BMD was obtained at 3.3 degrees of supination. Conclusion : In the case of the measurement of BMD in the distal radius with a neutral position, the rotational angle of the distal radius is close to supination. Pronation is needed for the constant measurement of BMD in the distal radius with the rotation angle measuring at the lowest BMD and about five degrees of pronation of the distal radius is recommended.

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Structural and optical properties of Ni-substituted spinel $LiMn_2O_4$ thin films (니켈 치환된 스피넬 LiMn2O4 박막의 구조적, 광학적 성질)

  • Lee, Jung-Han;Kim, Kwang-Joo
    • Journal of the Korean Vacuum Society
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    • v.15 no.5
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    • pp.527-533
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    • 2006
  • Spinel $LiNi_xMn_{2-x}O_4$ thin films were synthesized up to x = 0.9 by a sol-gel method employing spin-coating. The Ni-substituted films were found to maintain cubic structure at low x but to exhibit tetragonal structure for $x{\geq}0.6$. Such cubic-tetragonal phase transition indicates that $Ni^{3+}(d7)$ ions with low-spin $(t_{2g}^6,e_g^1)$ state occupy the octahedral sites of the compound, thus being subject to the Jahn-Teller distortion. By x-ray photoelectron spectroscopy both $Ni^{2+}$ and $Ni^{3+}$ ions were detected. Optical properties of the $LiNi_xMn_{2-x}O_4$ films were investigated by spectroscopic ellipsometry (SE) in the visible?ultraviolet range. The measured dielectric function spectra by SE mainly consist of broad absorption structures attributed to charge-transfer (CT) transitions, $O^{2-}(2p){\rightarrow}Mn^{4+}(3d)$ for 1.9 $(t_{2g})$ and $2.8{\sim}3.0$ eV $(e_g)$ structures and $O^{2-}(2p){\rightarrow}Mn^{3+}(3d)$ for 2.3 $(t_{2g})$ and $3.4{\sim}3.6$ eV $(e_g)$ structures. Also, sharp absorption structures were observed at about 1.6, 1.7, and 1.9 eV, interpreted as due to d-d crystal-field transitions within the octahedral $Mn^{3+}$ ion. The strengths of these absorption structures are reduced by the Ni substitution. Rapid reduction of the CT transition strength involving the eg states for x = 0.6 is attributed to the reduced wavefunction overlap between the $e_g$ and the $O^{2-}(2p)$ states due to the tetragonal extension of the lattice constant by the Jahn-Teller effect.

Comparison of True and Virtual Non-Contrast Images of Liver Obtained with Single-Source Twin Beam and Dual-Source Dual-Energy CT (간의 단일선원 Twin Beam과 이중선원 이중에너지 전산화단층촬영의 비조영증강 영상과 가상 비조영증강 영상의 비교 연구)

  • Jeong Sub Lee;Guk Myung Choi;Bong Soo Kim;Su Yeon Ko;Kyung Ryeol Lee;Jeong Jae Kim;Doo Ri Kim
    • Journal of the Korean Society of Radiology
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    • v.84 no.1
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    • pp.170-184
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    • 2023
  • Purpose To assess the magnitude of differences between attenuation values of the true non-contrast image (TNC) and virtual non-contrast image (VNC) derived from twin-beam dual-energy CT (tbDECT) and dual-source DECT (dsDECT). Materials and Methods This retrospective study included 62 patients who underwent liver dynamic DECT with tbDECT (n = 32) or dsDECT (n = 30). Arterial VNC (AVNC), portal VNC (PVNC), and delayed VNC (DVNC) were reconstructed using multiphasic DECT. Attenuation values of multiple intra-abdominal organs (n = 11) on TNCs were subsequently compared to those on multiphasic VNCs. Further, we investigated the percentage of cases with an absolute difference between TNC and VNC of ≤ 10 Hounsfield units (HU). Results For the mean attenuation values of TNC and VNC, 33 items for each DECT were compared according to the multiphasic VNCs and organs. More than half of the comparison items for each DECT showed significant differences (tbDECT 17/33; dsDECT 19/33; Bonferroni correction p < 0.0167). The percentage of cases with an absolute difference ≤ 10 HU was 56.7%, 69.2%, and 78.6% in AVNC, PVNC, and DVNC in tbDECT, respectively, and 70.5%, 78%, and 78% in dsDECT, respectively. Conclusion VNCs derived from the two DECTs were insufficient to replace TNCs because of the considerable difference in attenuation values.

Multi-classification of Osteoporosis Grading Stages Using Abdominal Computed Tomography with Clinical Variables : Application of Deep Learning with a Convolutional Neural Network (멀티 모달리티 데이터 활용을 통한 골다공증 단계 다중 분류 시스템 개발: 합성곱 신경망 기반의 딥러닝 적용)

  • Tae Jun Ha;Hee Sang Kim;Seong Uk Kang;DooHee Lee;Woo Jin Kim;Ki Won Moon;Hyun-Soo Choi;Jeong Hyun Kim;Yoon Kim;So Hyeon Bak;Sang Won Park
    • Journal of the Korean Society of Radiology
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    • v.18 no.3
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    • pp.187-201
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    • 2024
  • Osteoporosis is a major health issue globally, often remaining undetected until a fracture occurs. To facilitate early detection, deep learning (DL) models were developed to classify osteoporosis using abdominal computed tomography (CT) scans. This study was conducted using retrospectively collected data from 3,012 contrast-enhanced abdominal CT scans. The DL models developed in this study were constructed for using image data, demographic/clinical information, and multi-modality data, respectively. Patients were categorized into the normal, osteopenia, and osteoporosis groups based on their T-scores, obtained from dual-energy X-ray absorptiometry, into normal, osteopenia, and osteoporosis groups. The models showed high accuracy and effectiveness, with the combined data model performing the best, achieving an area under the receiver operating characteristic curve of 0.94 and an accuracy of 0.80. The image-based model also performed well, while the demographic data model had lower accuracy and effectiveness. In addition, the DL model was interpreted by gradient-weighted class activation mapping (Grad-CAM) to highlight clinically relevant features in the images, revealing the femoral neck as a common site for fractures. The study shows that DL can accurately identify osteoporosis stages from clinical data, indicating the potential of abdominal CT scans in early osteoporosis detection and reducing fracture risks with prompt treatment.

The Diagnosis and Treatment of Osteoporosis (골다공증의 진단과 치료)

  • Moon, Jun-Sung;Won, Kyu-Chang
    • Journal of Yeungnam Medical Science
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    • v.25 no.1
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    • pp.19-30
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    • 2008
  • Osteoporosis, a disease characterized by low bone mass and microarchitectural deterioration of bone tissue leading to enhanced bone fragility and fracture risk, is a major public health problem. The diagnostic methods for osteoporosis include simple radiography, bone scan, DXA (Dual energy X-ray Absortiometry) and biochemical markers of bone turnover. Optimal treatment and prevention of osteoporosis require modification of risk factors, particularly smoking cessation, adequate physical activity, and attention to diet, in addition to pharmacologic intervention. The estrogens and raloxifene both prevent bone loss in postmenopausal women, and the estrogens probably also decrease the risk of first fracture. There is good evidence that raloxifene prevents further fractures in postmenopausal women who already have had fractures and some evidence that estrogen does as well. Bisphosphonate prevents bone loss and reduces fractures in healthy and osteoporotic postmenopausal women and in osteoporotic men as well. Risedronate is more potent and has fewer side effects than alendronate and reduces the incidence of fractures in osteoporotic women. Calcitonin increases bone mineral density in early postmenopausal women and men with idiopathic osteoporosis, and also reduces the risk of new fractures in osteoporotic women. All of the agents discussed above prevent bone resorption, whereas teriparatide and strontium increase bone formation and are effective in the treatment of osteoporotic women and men. New avenues for targeting osteoporosis will emerge as our knowledge of the regulatory mechanisms of bone remodeling increases, although issues of tissue specificity may remain to be addressed.

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