인체 흉부 모형 팬텀을 이용한 컴퓨터방사선영상에서 노출지수의 적용 사례 연구

정회원,민정환,Jeong, Hoi-Woun,Min, Jung-Whan 대한방사선과학회 2018 방사선기술과학 Vol.41 No.6

As the use of digital radiographic system has been expanded, there are some concerns an increase about in patient of radiation dose. Therefore, International Electro-technical Commission (IEC) has been proposed a standard foe exposure index (EI). In this study, the EI was measured on human chest model using computed radiography (CR). Radiation quality used RQA5 of IEC62494-1. After acquiring the chest anterior posterior image (Chest AP) by using the phantom, the EI was obtained by applying the system response. In this study, we have analyzed the images with the detector size (Full filed ROI) and the optimized image (Fit filed ROI). The EI increased proportionally with radiation dose increase. Due to the discrete increase in pixel value, the EI showed an exponential increase. The discrete increase in noise equivalent quanta (NEQ) resulted in a discrete increase in the EI. The EI of the two images used in this study increased with increasing NEQ but showed different increments. For the measurement of the EI, IEC standards must be followed. The EI should be used as an index to evaluate the image quality for quality control of X-ray image rather than as an indicator of exposure dose. When calculating the EI, the system response should be applied depending on whether or not the grid is used. The size of the field should be obtained by including only the necessary parts.

비정질 평판형 측정기를 이용한 디지털 방사선 영상의 특징

정회원,김정민,정만희,임은경,Jeong, Hoi-Woun,Kim, Jung-Min,Jeong, Man-Hee,Im, Eun-Kyung 대한디지털의료영상학회 2006 대한디지털의료영상학회논문지 Vol.8 No.1

The rapid development in digital acquisition technology in radiography has not been accompanied by information regarding optimum radiolographic technique for use with an amorphus silicon flat panel detector. The purpose of our study was to compared imaging characteristics and image quality of an amorphus silicon flat panel detectors for digital chest radiography. All examinations were performed by using an amorphus silicon flat panel detector. Chest radiographs of an chest phantom were obtained with peak kilovoltage values of 60$\sim$150 kVp. Published data ell the effect of x-ray beam energy on imaging characteristics and image qualify when using an amorphus silicon flat panel detector. It is important that radiographers are aware of optimum kVp selection for an amorphus silicon flat panel detector system, particularly for the commonly performed chest examination.

디지털 방사선 영상의 편차지수를 이용한 의료영상 품질관리에 관한 연구

정회원(Hoi-Woun Jeong),민정환(Jung-Whan Min) 대한방사선과학회(구 대한방사선기술학회) 2020 방사선기술과학 Vol.43 No.2

In a digital radiation system using a Flat Panel Detector, we attempted to the quality control of digital radiography system using the Exposure Index and Deviation Index. Calibration was performed with the radiation quality suggested by the International Electrotechnical Commission, and through an experiment using a phantom, appropriate inspection radiation conditions applicable to medical institutions were selected. The study was conducted using the selected radiation conditions. Through those chest posterior anterior image, information such as examination conditions and exposure index was obtained. The deviation index was derived by analyzing the exposure index based on the target exposure index calculated by the phantom study. As for the analyzed exposure index, 97.1% was distributed within the range of ± 2.0 based on the deviation index. Quality control of medical images should be performed through management of inspection conditions through exposure index and deviation index and management of medical images.

진단영역 넓은 선속 X선 에너지에 대한 차폐물질의 투과 특성

정회원(Hoi-woun Jeong),김정민(Jung-min Kim),임송수(Song-Shei Lin) 대한방사선과학회(구 대한방사선기술학회) 2004 방사선기술과학 Vol.27 No.4

진단영역에서 사용하는 넓은 선속 X선 에너지에 대한 차폐물질의 투과 특성을 Archer의 수학적 모델을 적용하여 나타내었다. 인버터 방식의 고전압발생장치를 사용하는 X선 발생장치를 사용하여 관전압 60kVp부터 140kVp까지의 범위에서 납, 철, 콘크리트, 유리등의 차폐체의 투과 특성을 나타내었다. 이러한 인버터 방식의 고전압발생장치를 사용하는 진단영방사선발생장치의 관전압별 투과더는 진단방사선발생장치를 사용하는 작업공간에서의 차폐 설계 시 차폐물질의 종류와 두께의 설정에 도움이 될 것 이다. The application of analytical model(Archer et at 1983) to shielding calculations in diagnostic radiology combined with measurements of the broad beam transmission properties of lead, steel, conciete, and plate glass for x-ray tube potential of 60-140 kVp using an x-ray inverter generatol and total initial beam filtration sufficient to provide half-valve layer representative of those found in common practice and required by regulatory agencies Our transmission measurements and numerical fits to the mathematical model of broad beam transmission(Archer et al 1983) will assist medical or health physicist faced With the task of designing protective barriers for medical diagnostic x-ray facilities

다양한 디지털 방사선 시스템의 물리적 영상 특성 조사

정회원(Hoi-Woun Jeong),민정환(Jung-Hwan Min),윤용수(Yong-Su Yoon),김정민(Jung-Min Kim) 대한방사선과학회(구 대한방사선기술학회) 2017 방사선기술과학 Vol.40 No.3

본 연구는 전하결합소자(charged coupled device; CCD), CR (computed radiography), 평판형검출기(flat panel detector; FPD) 등을 사용하는 다양한 디지털 방사선(digital radiography; DR) 시스템의 물리적 영상 특성의 평가를 실시한 것이다. 본 연구에서 적용된 영상 특성은 신호응답특성(system response), 해상력특성(modulation transfer function;MTF), 잡음특성(wiener spectrum; WS), 양자검출효율(detective quantum efficiency; DQE) 등이며 이를 통하여 DR 시스템의 성능을 비교하였다. CCD의 신호응답특성은 입사선량에 비례하여 증가하였으며, CR과 FPD는 입사선량의 증가에 대수적 비례 관계를 보이면서 증가하였다. MTF는 CR과 FPD는 유사한 경향을 나타내었지만 CCD는 떨어지는 값을 나타내었다. WS는 FPD가 가장 낮았고, CR, CCD 순으로 증가하였다. DQE는 FPD, CR, CCD의 순으로 나타났다. DR 시스템은 영상수용체의 종류에 따라 서로 다른 영상 특성이 나타났다. 의료영상 획득 시 DR 시스템을 올바르게 사용하려면 영상의 물리적 특성을 정확히 알고 사용하는 것이 중요하다. We aimed to evaluate the physical imaging properties in various digital radiography systems with charg-ed coupled device (CCD), computed radiography (CR), and indirect flat panel detector (FPD). The imaging properties measured in this study were modulation transfer function (MTF) wiener spec-trum (WS), and detective quantum efficiency (DQE) to compare the performance of each digital radiog-raphy system. The system response of CCD were in a linear relationship with exposure and that of CR and FPD were proportional to the logarithm of exposure. The MTF of both CR and FPD indicated a similar tendency but in case of CCD, it showed lower MTF than that of CR and FPD. FPD showed the lowest WS and also indicated the highest DQE among three systems. According to the results, digital radiography system with different type of image receptor had its own image characteristics. Therefore, it is important to know the physical imaging characteristics of the digital radiography system accurately to obtain proper image quality.

CsI(TI) Indirect Flat Panel Detector의 선질에 따른 물리적 영상 평가

정회원(Hoi-Woun Jeong),민정환(Jung-Hwan Min),김정민(Jung-Min Kim),박민석(Min-Seok Park),이광용(Gaung-Young Lee) 대한방사선과학회 2012 방사선기술과학 Vol.35 No.2

간접형 CsI flat-panel detector (FPD)의 해상특성(modulation transfer function, MTF), 잡음특성(Wiener spectrum or noise power spectrum, NPS), 양자검출효율(detective quantum efficiency, DQE)을 측정하고 평가하기 위하여 본 실험을 실시하였다. IEC에서 권고한 실험방법을 따라 RQA3, RQA5, RQA7, RQA9의 방사선 선질을 사용하였다. MTF는 egde법을 사용하였다. Wiener spectrum은 조사 영역내에서 획득한 영상의 푸리에 변화를 통하여 구하였다. DQE는 MTF, WS(NPS), X선 입력 및 입력 광자량을 사용하여 평가하였다. 특성곡선은 RQA3와 RQA5, RQA7, RQA9과는 차이가 발생하였다. MTF는 X선 선질과는 상관없이 일정하였다. WS(NPS)은 X선 양이 증가 할수록 감소하였으며, RQA3, RQA5, RQA7, RQA9순으로 감소하였다. DQE는 1mR에서 가장 우수했으며, RQA3, RQA5, RQA7, RQA9순으로 감소하였다. FPD의 물리적 영상 특성을 입력 선질에 따라 다를 수 있다. 본 연구를 통하여 디지털 방사선 시스템의 바르게 사용하려면 FPD의 물리적 영상 특성을 아는 것이 중요함을 인식하게 되었다. The purpose of this work was to evaluate an amorphous silicon cesium iodide based indirect flat-panel detector (FPD) in terms of their modulation transfer function (MTF), Wiener spectrum (WS, or noise power spectrum, NPS), and detective quantum efficiency (DQE). Measurements were made on flat-panel detector using the International Electrotechnical Commission (IEC) defined RQA3, RQA5, RQA7, and RQA9 radiographic technique. The MTFs of the systems were measured using an edge method. The WS(NPS) of the systems were determined for a range of exposure levels by two-dimensional (2D). Fourier analysis of uniformly exposed radiographs. The DQEs were assessed from the measured MTF, WS(NPS), exposure, and estimated ideal signal-to-noise ratios. Characteristic curve in the RQA3 showed difference in the characteristic curve from RQA5, RQA7, RQA9. MTFs were not differences according to x-ray beam quality. WS(NPS) was reduced with increasing dose, and RQA 3, RQA5, RQA7, RQA9 as the order is reduced. DQE represented the best in the 1mR, RQA 3, RQA5, RQA7, RQA9 decrease in the order. The physical imaging characteristics of FPD may also differ from input beam quality. This study gives an initial motivation that the physical imaging characteristics of FPD is an important issue for the right use of digital radiography system.

실리콘 혼합 차폐체의 개발과 성능비교

정회원(Hoi-Woun Jeong),민정환(Jung-Whan Min) 대한방사선과학회(구 대한방사선기술학회) 2023 방사선기술과학 Vol.46 No.3

A shield was made by mixing materials such as bismuth(Bi) and barium(Ba) with silicon to evaluate its shielding ability. Bismuth was made into a shield by mixing a bismuth oxide(Bi2O3) colloidal solution and a silicon base and applied to a fibrous fabric, and barium was made by mixing lead oxide(PbO) and barium sulfate(BaSO4) with a silicon curing agent and solidifying it to make a shield. The test was conducted according to the lead equivalent test method for X-ray protective products of the Korean Industrial Standard. The experiment was conducted by increasing the shielding body one by one from the test condition of 60 kVp, 200 mA, 0.1sec and 100 kVp, 200 mA, 0.1 sec. At 60 kVp, 2 lead oxide-barium sulfate shields, 2 bismuth oxide 1.5 mm shields, and 5 bismuth oxide 0.3 mm shields showed shielding ability equal to or higher than that of lead 0.5 mm. At 100 kVp, 2 lead oxide-barium sulfate shields and 2 bismuth oxide 1.5 mm shields showed shielding ability equal to or higher than that of lead 0.5 mm. It was confirmed that when using 2 pieces of lead oxide-barium sulfate and 1.5 mm of bismuth oxide, respectively, it has shielding ability equivalent to that of lead. Bismuth oxide and lead oxide-barium sulfate are lightweight and have excellent shielding ability, thus they have excellent properties to be used as an apron for radiation protection or other shielding materials.

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.

차트 각도를 이용한 해상력 특성 평가

민정환(Jung-Whan Min),정회원(Hoi-Woun Jeong) 대한방사선과학회(구 대한방사선기술학회) 2021 방사선기술과학 Vol.44 No.4

This study aim was quantitative assessment of MTFs of spectrum of the square wave chart images and Coltman chart images for 0o, 1.7o, 2.2o, 2.9o, 4.1o by using chart method. In general device was AccuRay-650 (DK Medical System, Korea) used, indirect flat panel detector(FPD) Aero (Konica, Japan) used and MATLAB R2019a (MathWorks, USA) used. The result of comparison for each angle of MTF the edge image was highest quantitatively value for MTF finding of showed the best value of 0.1 based on the frequency of 3.5 mm-1, value of 0.1 based on the square wave was frequency of 3.0 mm-1 and value of 0.1 based on the Coltman transform was frequency of 2.4 mm-1. In this study it was significant that the methodology of the international Electro-technical Commission was applied mutandis by using the Fujita method within 2∼3o.

비정질 평판형 측정기를 이용한 디지털 흉부 방사선 영상에서의 효과적인 관전압 선택

김정민(Jung-Min Kim),정회원(Hoi-Woun Jeong),임은경(Eun-Kyung Im) 대한방사선과학회(구 대한방사선기술학회) 2005 방사선기술과학 Vol.28 No.4

디지털 의료 영상의 빠른 발전은 새로운 기술-비정질 평판형 측정기-에 대한 최적의 기술이 동행되지 못했다. 이번 실험으로 비정질 평판형 측정기를 사용한 흉부 방사선 영상의 대한 환자선량과 영상의 화질에 대하여 비교하였다. 모든 실험은 비정질 평판형 측정기를 사용하였다. 흉부 팬텀을 사용한 흉부 방사선영상은 관전압 60~150㎸p에서 획득하였다. 이번 실험을 통하여 획득된 비정질 평판형 측정기를 사용한 X-선 에너지에 대한 영상의 질과 환자선량에 관련된 정보들을 보고한다. 이 정보는 비정질 평판형 측정기를 사용한 시스템에서 최적의 관전압의 선정에 효과적인 정보를 제공하며, 특히 일반적인 흉부 검사에 적용될 수 있을 것이다. The rapid development in digital acquisition technology in radiography has not been accompanied by information regarding optimum radiolographic technique for use with an amorphus silicon flat panel detector. The purpose of our study was to compared image quality and radiation dose of an amorphus silicon flat panel detectors for digital chest radiography. All examinations were performed by using an amorphus silicon flat panel detector. Chest radiographs of an chest phantom were obtained with peak kilovoltage values of 60~150㎸p. Published data on the effect of x-ray beam energy on image quality and patient dose when using an amorphus silicon flat panel detector. It is important that radiographers are aware of optimum kVp selection for an amorphus silicon flat panel detector system, particularly for the commonly performed chest examination.