3.0T 자기공명영상을 이용한 해상력 특성에 대한 연구

민정환,정회원,한지현,이시내,한송이,김기원,김현수,손진현 대한방사선과학회 2020 방사선기술과학 Vol.43 No.4

This study was purpose to quantitative evaluation of edge method of modulation transfer function(MTF) and physical image characteristics of by obtain the optimal edge image by using magnetic resonance imaging(MRI). The MRI equipment was used (MAGNETOM Vida 3.0T MRI, Siemense healthcare system, Germany) and the head/neck matrix shim MR coil were 20 channels(elements) receive coil. The MTF results of showed the best value of 0.294 based on the T2 Nyquist frequency of 1.0 mm-1. The MTF results of showed that the T1 image is 0.160, the T1 CE image is 0.250, T1 Conca2 image is 0.043, and the T1 CE (Concatenation) Conca2 image is 0.190. The T2 image highest quantitatively value for MTF. The physical image characteristics of this study were to that can be used efficiently of the MRI and to present the quantitative evaluation method and physical image characteristics of 3.0T MRI.

변조전달함수 방법에서 엣지 장치 설정에 대한 각도 최적화 평가

민정환,정회원 대한방사선과학회 2020 방사선기술과학 Vol. No.

This study was purpose to evaluation of Modulation Transfer Function in Measurements by using the International electrotechnical commission standard(IEC 62220-1) which were edge device each angle by using edge method. In this study was Aero(Konica, Japan) image receptor which is a indirect Flat panel detector(FPD) was used. The size of matrix 1994 × 2430 (14″× 17″inch) which performed 12 bit processing and pixel pitch is 175 μm. The results of shown as MTF measurements at IEC standard. The amount of data seemed reasonable and at an MTF value of 0.1 the spatial frequencies were 2.56 cycles/mm at an angle of 2.4o. MTF value of 0.5 the spatial frequencies were 1.32 cycles/mm at an angle of 2.4o. This study were to evaluate MTF by setting each angle 2.0o∼2.8o degrees the most effective optimal edge angle and to suggest the quantitative methods of measuring by using IEC. .

휘진성 형광체 (BaFBr:Eu2+)를 이용한 영상의학분야에서 산란선 특성에 관한 평가

민정환,한성규,김정민,이주아,김기원,정회원 대한방사선과학회 2014 방사선기술과학 Vol.37 No.2

본 연구는 휘진성 형광체를 이용하여 디지털 의료영상시스템의 환경에서 산란선에 의한 영상 특성을 연구하였다. 아크릴 팬텀을 사용하여 관전압 (50kVp부터 120kVp까지), 조사야(4×4cm2부터 26×26cm2까지), 팬텀의 두께 (1cm부터 25cm까지)를 각각 변화시켜 실험을 실시하였다. 실험 방법은 영상을 ImageJ와 특성곡선을 사용하여 분석하였다. 관전압은 50kVp~70kVp에서는 관전압이 증가하면서 일차선에 대한 산란선의 비율도 증가하지만, 80kVp부터는 일정한 비율을 나타내었다. 조사야가 증가함에 따라 일차선에 대한 산란선의 비율은 증가한다. 팬텀 두께가 증가함에 따라 산란선이 증가한다.

텅스텐 엣지 블록을 이용하여 Megavoltage (MV) 영상의 질 평가

민정환,손진현,김기원,이정우,손순룡,백금문,김정민,김연래,정재용,김상영,이도완,최보영,Min, Jung-Whan,Son, Jin-Hyun,Kim, Ki-Won,Lee, Jung-Woo,Son, Soon-Yong,Back, Geum-Mun,Kim, Jung-Min,Kim, Yeon-Rae,Jung, Jae-Yong,Kim, Sang-Young,Lee, Do- 한국의학물리학회 2012 의학물리 Vol.23 No.3

최근 백만 볼트 영상(megavoltage imaging, MVI)에서 급격히 발전해 온 디지털 방사선영상(digital radiography, DR)은 치료용 방사선영상 기술이 발전함에 따라 매우 정확하면서 간단하게 측정할 수 있는 일반적인 정도관리(quality assurance, QA) 방법을 요구하게 되었다. 본 연구의 목적은 일반적인 QA 방법과 computed radiography (CR) 장비를 사용하여 MVI의 변조전달함수(modulation transfer function, MTF), 잡음전력스펙트럼(noise power spectrum, NPS), 양자검출효율(detective quantum efficiency, DQE)를 평가하고자 하였다. 텅스텐으로 구성된 $19{\times}10{\times}1cm^3$ 두께의 엣지(edge) 블록을 사용하였으며, 6 MV energy를 사용하였다. 또한 검출기는 CR-IP (image plate), CR-IP-lead, the CR-IP-back (lanex TM fast back screen), CR-IP-front (lanex TM fast front screen)를 사용하였으며, pre-sampling MTF를 계산하였다. CR-IP의 MTF는 0.70 lp/mm를 나타내었고, CR-IP front의 MTF는 1.10 lp/mm로서 가장 높은 값의 고해상도 공간분해능을 보였다. 가장 우수한 검출기의 NPS는 CR-IP front screen에서 확인되었다. 공간주파수가 증가함에 따라 1.0 cycles/mm의 가까운 DQE를 획득하였다. 본 연구결과로서 자체 제작한 엣지 블록 방법은 MVI의 MTF, NPS, DQE를 평가하는 일반적인 QA 방법으로 사용될 수 있음을 확인하여 주었다. Digital Radiography (DR) has rapidly developed in megavoltage X-ray imaging (MVI). Thus, a very simple and general quality assurance (QA) method is required. The purpose of this study was to evaluate the modulation transfer function (MTF), the noise power spectrum (NPS) and the detective quantum efficiency (DQE) for MVI using general QA method and computed radiography (CR) device. We used tungsten edge block with $19{\times}10{\times}1cm^3$ thickness and 6MV energy. For detector, CR-IP (image plate), CR-IP-lead, the CR-IP-back (lanex TM fast back screen), CR-IP-front (lanex TM fast front screen) were used and pre-sampling MTF was calculated. The MTF of CR-IP-front showed the highest value with 1.10 lp/mm although the CR-IP showed the only 0.70 lp/mm. The best NPS was observed in CR-IP front screen. According to the increase in spatial frequency, our results showed that DQE was approximately 1.0 cycles/mm. The present study demonstrates that the QA method with our home-made edge block can be used to evaluate MTF, NPS and DQE for MVI.

간접평판형 검출기에서 변조전달함수 측정 시 Edge 각도에 따른 비교 연구

민정환,정회원 대한방사선과학회 2019 방사선기술과학 Vol.42 No.4

This study was purpose to compare image quality of Indirect digital radiography (IDR) system by using the International electro-technical commission standard(IEC 62220-1) which were applied to IEC in medical imaging. To evaluation the analysis of Modulation transfer function(MTF) measurements edge device each angle by using edge method. In this study, Aero (Konica, Japan) which is Indirect flat panel detector(FPD) was used, the size of image receptor matrix 1994 × 2430 which performed 12bit processing and pixel pitch is 175 μm. In IEC standard method were applied to each angle were compared. The results of shown as LSF at 2.0o and 3.0o angeles. Shape is constant and shows smooth shape. The amount of data seemed reasonable and 2.19 cycles/mm and 2.01 cycles/mm at a spatial frequency of 2.0o and 3.0o at an MTF value of 0.1. At an MTF value of 0.5, the spatial frequencies were 2.0o and 1.11 cycles/mm and 0.93 cycles/mm at an angle of 3.0o. This study were to evaluate MTF by setting the each 2∼3o each angle and to suggest the quantitative methods of measuring by using IEC.

변조전달함수 방법에서 엣지 장치 설정에 대한 각도 최적화 평가

민정환,정회원,Min, Jung-Whan,Jeong, Hoi-Woun 대한방사선과학회 2020 방사선기술과학 Vol. No.

This study was purpose to evaluation of Modulation Transfer Function in Measurements by using the International electrotechnical commission standard(IEC 62220-1) which were edge device each angle by using edge method. In this study was Aero(Konica, Japan) image receptor which is a indirect Flat panel detector(FPD) was used. The size of matrix 1994 × 2430 (14"× 17" inch) which performed 12 bit processing and pixel pitch is 175 ㎛. The results of shown as MTF measurements at IEC standard. The amount of data seemed reasonable and at an MTF value of 0.1 the spatial frequencies were 2.56 cycles/mm at an angle of 2.4°. MTF value of 0.5 the spatial frequencies were 1.32 cycles/mm at an angle of 2.4°. This study were to evaluate MTF by setting each angle 2.0°~2.8° degrees the most effective optimal edge angle and to suggest the quantitative methods of measuring by using IEC.

초음파 의료영상에서 ATS 535H 팬텀을 이용한 해상력 특성 평가

민정환,정회원,강혜경 대한방사선과학회 2023 방사선기술과학 Vol.46 No.1

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Comparison of Noise Power Spectrum Methodologies in Measurements by Using Megavoltage X-ray Energies

민정환,손진현,정회원,김정민,성열훈,Soon-Yong Son,김호경,김상영,이도완,정재용,서태석,최보영 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.1

The noise power spectrum (NPS) is one of the most general methods for measuring the noise amplitude and the quality of an image acquired from a uniform radiation field. The purpose of this study was to compare different NPS methodologies by using megavoltage X-ray energies. The NPS evaluation methods in diagnostic radiation were applied to therapy using the International Electrotechnical Commission standard (IEC 62220-1). In order to measure the region of interest (ROI) of the NPS, we used the following five factors: the overlapping impact, the non-overlapping impact, the penumbra, the flatness and different ROI sizes. We used NPS from four different types of detectors,the CR-IP (computed radiography image plate: photo-stimulable phosphor screen), the CR-IP-lead (hexalon lead screen), the CR-IP-back [lanex TM fast back screen: {terbium-doped gadolinium oxysulfide granular phosphor screen (Gd2O2S:Tb,133 mg/cm2)} + 1-mm-thick copper plate] and the CR-IP-front (lanex TM fast front screen). A Kodak 2000 RT photo-stimulable phosphor-based computed radiographic (CR) system showed that the normalized noise power spectrum (NNPS)curve gradually decreased, in compliance with increasing spatial resolution. In addition, each detector showed a different reactivity of the NPS to megavoltage. The results of multivariate analysis of variance (MANOVA) test (methods × detectors) revealed significant main effects of the methods [F(1, 4) = 53.543, P = 0.001] and of the detectors [F(1, 4) = 17.556, P = 0.001]. The present study revealed that various factors could be employed to produce megavoltage imaging (MVI) of the NPS and as a baseline standard for NPS control in MVI.

타원곡선암호 알고리즘을 이용한 종단간 MQTT 보안 프로토콜

민정환,김영곤 한국인터넷방송통신학회 2019 한국인터넷방송통신학회 논문지 Vol.19 No.5

Internet of Things (IoT) is proliferating to provide more intelligent services by interconnecting various Internet devices, and TCP based MQTT is being used as a standard communication protocol of the IoT. Although it is recommended to use TLS/SSL security protocol for TCP with MQTT-based IoT devices, encryption and decryption performance degenerates when applied to low-specification / low-capacity IoT devices. In this paper, we propose an end-to-end message security protocol using elliptic curve cryptosystem, a lightweight encryption algorithm, which improves performance on both sides of the client and server, based on the simulation of TLS/SSL and the proposed protocol. 다양한 인터넷 장치들을 상호 연결하여 보다 지능적인 서비스를 제공하기 위한 사물인터넷(IoT)이 확산되고 있으며, 사물인터넷의 대표적 통신 프로토콜로 TCP 기반의 MQTT가 사용되고 있다. MQTT 기반의 IoT 장치 간 데이터암호화 기술로 TCP의 경우 TLS/SSL 보안 프로토콜 사용을 권고하고 있지만, 저사양/저용량 IoT 장치에 적용할 경우암복호화로 인한 성능 저하가 초래된다. 본 논문에서는 MQTT 프로토콜로 연결된 IoT 장치 간에 경량화 암호 알고리즘인 타원곡선암호를 적용한 종단간 메시지 보안 프로토콜을 제안하며, TLS/SSL과 제안 프로토콜에 대한 시뮬레이션을통해 제안 프로토콜이 클라이언트와 서버 양측에서 성능이 향상됨을 검증하였다.

변조전달함수 방법에서 엣지 장치 설정에 대한 각도 최적화 평가

민정환(Jung-Whan Min),정회원(Hoi-Woun Jeong) 대한방사선과학회(구 대한방사선기술학회) 2020 방사선기술과학 Vol. No.

This study was purpose to evaluation of Modulation Transfer Function in Measurements by using the International electrotechnical commission standard(IEC 62220-1) which were edge device each angle by using edge method. In this study was Aero(Konica, Japan) image receptor which is a indirect Flat panel detector(FPD) was used. The size of matrix 1994 × 2430 (14″× 17″inch) which performed 12 bit processing and pixel pitch is 175 μm. The results of shown as MTF measurements at IEC standard. The amount of data seemed reasonable and at an MTF value of 0.1 the spatial frequencies were 2.56 cycles/mm at an angle of 2.4°. MTF value of 0.5 the spatial frequencies were 1.32 cycles/mm at an angle of 2.4°. This study were to evaluate MTF by setting each angle 2.0°∼2.8° degrees the most effective optimal edge angle and to suggest the quantitative methods of measuring by using IEC.