• 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.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1998.05a
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• pp.126-131
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• 1998

DECT는 기존의 사설 교환시스템에 이동통신 서비스를 제공하기 위한 디지탈 방식의 무선통신 규약으로 ETSI에 의해 표준화되었다. 본 논문에서는 사설교환기에 이동통신 서비스를 제공하기 위해 ETSI에 의해 권고된 DECT 표준안을 기초로 DECT 교환국과 기지국을 개발하였으며, 이의 구현 방법에 관하여 서술하였다. DECT 시스템의 호제어타스크를 구현함으로써 이동중 착발신이 가능하도록 하였고, 부분해제 기능을 구현함으로써 효율적인 트랜젝션의 처리가 가능하도록 하였다.

• Journal of radiological science and technology
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• v.40 no.2
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• pp.311-316
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• 2017

Generally assessing bone mineral density (BMD) were performed on dual energy X-ray absorptiometry (DEXA) the same as dual energy CT (DECT) with a rapid-kVp switching. The purpose of this study is to compare the different of BMD value between DEXA and DECT method, and evaluate usefulness of DECT method. Using scanner for BMD measurements were GE, Healthcare Discovery 750 HD for DECT and Hologic QDR 4500W for DEXA. For compare BMD value in each method, scanned lumbar spine phantom and subjects visiting Korean National Cancer Center from April 2015 to December 2015, records of 50 patients. This study was approved by the Institutional Review Board. The mean BMD value measures for spine phantom and for subjects in each scanners presented strong correlation (r=0.948 with p<0.05 for phantom; r=0.635 with p<0.05 and Kendall's tau $({\tau})=0.46$ with p<0.05 for subjects) and linear relationship between DECT and conventional DEXA. DECT technique for BMD measurement will provide a very useful methodology without additional radiation dose.

• Journal of the Korean Society of Radiology
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• v.17 no.3
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• pp.417-422
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• 2023

In this study, normal saline was diluted with the contrast medium at a certain ratio for the purpose of reducing the image quality poor and side effects caused by the contrast medium during CT examination. At this time, by finding the energy level of DECT that can compensate for the decrease in contrast of the image according to the degree of dilution, the usefulness of applying DECT for compensating the difference in image contrast was investigated through comparative analysis by applying SNR, CNR, and SSIM. As a result, when a dilution ratio of 4 (contrast medium): 6 (normal saline) and the energy level of DECT of 65 keV were applied, the contrast difference was the most similar to that when using the undiluted contrast medium. At this time, SNR was 813.71 ± 37.6, CNR was the highest at 921.87 ± 17.1, and SSIM index was measured at 0.851, which is the most similar to 1. The results of this study are meaningful in providing basic information for finding the appropriate dilution rate and energy level for each examination site through future clinical studies. It is believed that it can be reduced.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.11a
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• pp.356-362
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• 1999

DECT(Digital Enhanced Cordless Telecommunications) is the communication protocol and the pico-cellular network that provides a PABX with mobile services on the local area within its cell radius of about 100 to 200m. Compared with GSM, DECT provides low-cost communication services based on the PSTN and it is an ideal supplementary method for the type of in-building mobile communication. In this paper we presented the implementation methods and techniques of the DECT data link communication layer that provided reliable communication services to the upper network layer by performing the functions of link controls, error controls, sequence controls, and flow controls.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1998.11a
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• pp.333-339
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• 1998

DECT는 기존의 사설 교환시스템에 이동통신 서비스를 제공하기 위한 디지탈 방식의 무선통신 규약으로 발신전용 무선전화 기술인 CT2의 기능 상의 제약을 극복하고, 빌딩외 옥내형 이동통신을 위한 GSM의 이상적인 보완책으로 각광을 받고 있다. 본 논문에서는 유선통신의 제약으로 인해 사용자가 이동중에는 통신서비스를 제공받을 수 업는 종래 사설교환기의 문제점을 극복하기 위해 ISDN 사설교환망과 DECT 이동통신망간에 연동을 위한 IWU의 프로토콜을 설계하고 구현하였다.

• Korean Journal of Radiology
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• v.22 no.6
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• pp.970-982
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• 2021

Dual-energy CT (DECT) provides insights into the material properties of tissues and can differentiate between tissues with similar attenuation on conventional single-energy imaging. In the conventional CT scanner, differences in the X-ray attenuation between adjacent structures are dependent on the atomic number of the materials involved, whereas in DECT, the difference in the attenuation is dependent on both the atomic number and electron density. The basic principle of DECT is to obtain two datasets with different X-ray energy levels from the same anatomic region and material decomposition based on attenuation differences at different energy levels. In this article, we discuss the clinical applications of DECT and its potential robust improvements in performance and postprocessing capabilities.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.4
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• pp.634-641
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• 2000

A switchable VCO for DECT handset is designed and fabricated. In dual mode radios, a single VCO is desired to operate at two different frequencies to meet the requirement of two mode(Tx, Rx). The three design types of switchable VCO are switched resonator VCO, switched mode VCO and dual band VCO. In this paper, we use the switched resonator VCO type using pin diode switch to change the total amount of capacitance in the tank circuit. At the bias condition of 3 V and 13mA, the output power and phase noise are better than6.5dBm and -104dBc/Hz at 25khz offset from the carrier, respectively , across the operating frequency range. From these results, the fabricated switched VCO is applicable to the DECT handset.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.1
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• pp.129-139
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• 1999

DECT(Digital Enhanced Cordless Telecommunications) is the communication protocol and the pico-cellular network that provides a PABX with mobile services on the local area within its cell radius of about 100 to 200m. Compared with GSM, DECT provides low-cost communication services based on the PSTN and it is an ideal supplementary method for the type of in-building mobile communication. In order to implement the data link communication layer of the DECT system, in this paper we analyzed and designed the structures and functions of it that provided reliable communication and real-time services to the upper network layer by performing the functions of link controls, error controls, sequence controls, and flow controls.

• Journal of the Korean Society of Radiology
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• v.18 no.2
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• pp.179-185
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• 2024

By applying the various energy spectrum imaging functions of DECT, To quantitatively distinguish between contrast agent and calcification, changes in image quality are analyzed by comparing CNR and SNR. We investigated the level of dose reduction during two scans and one VNC scan. As a result, contrast agent and calcification were best distinguished in the 70 keV area, CNR and SNR were excellent, and scan dose was reduced by about 26.5%. Therefore, by applying DECT, meaningful results were obtained that could visually and quantitatively distinguish between the intravascular contrast agent and the shade of calcification. If clinical research is conducted in the future considering the patient's age, gender, and body type, quantitative analysis of calcification will be possible even with intravascular contrast agent flowing in, which will have a significant effect in reducing the patient's scan dose and the burden of multiple scans.