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- 저자 : 차병열(Byung-Youl Cha) (검색결과 4 건)
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방사선치료 시뮬레이터의 비접속형관전압계 제작과 성능분석
김종언,윤천실,김성현,박창희,차병열,Kim, Jong-Eon,Yoon, Chun-Sil,Kim, Sung-Hyun,Park, Chang-Hee,Cha, Byung-Youl 한국의학물리학회 2006 의학물리 Vol.17 No.4
In this study, we have fabricated the noninvasive tube voltage meter which can observe the waveform of tube voltage and measure the tube voltage by using the Intensity of X-ray beam irradiated from radiotherapy simulator and also investigated the feasibility for clinical applications. Two pin photodiodes acting as X-ray detectors were arranged in parallel at the position of ${\pm}1.4cm$ in the y-axis of X-ray field and the aluminum filters with different thickness were placed above them. Using this detector, we could get the ratio ($r_{eff}$) of the relative output voltage which is proportional to the thickness of the filters. And the logarithm of effective peak tube voltage ($InkV_{p,eff}$) was obtained by Victoreen's NERO 6000M used as reference tube voltage meter. From the linear regression analysis of $r_{eff}$ and In $kV_{p,eff}$ the correlation coefficient (r) of linear equation was obtained to be 0.996 for the calibration of the tube voltage meter. Therefore, we suggest that the noninvasive tube voltage meter fabricated in this study can be used for clinical applications due to Its high accuracy. 본 연구에서는 방사선치료 시뮬레이터 장치에서 조사되는 X-선 빔의 강도로부터 관전압 측정과 관전압의 파형을 관찰 할 수 있는 비접속형 관전압계를 제작하였고, 그 성능을 분석하여 임상에 사용 가능성을 검토하였다. 관전압계의 검출부는 X-선 조사면(field)의 Y축 방향으로 ${\pm}1.4cm$ 지점에 두 개의 광다이오드를 배치하고 그 위에 두께가 다른 알루미늄여과체를 각각 놓아 구성하였다. 설정 피크 관전압에 대한 여과체의 두께 비에 비례하는 상대적인 출력 실효 전압비($r_{eff}$)를 측정하고, NERO 6000M 기준 관전압계로 설정 피크 관전압에 대한 실효 피크 관전압($kV_{p,eff}$)을 측정하여 자연 대수치를 구하였다. 관전압계의 교정을 위해 상대적인 출력 실효 전압 비($r_{eff}$)와 실효 피크 관전압 대수치($InkV_{p,eff}$)를 선형 회귀 분석하였다. 얻어진 선형 상관계수(r)는 0.996 이었다. 따라서 제작된 비접속형 관전압계는 충분한 정확도를 가지고 있어 임상에서의 사용이 가능하다고 생각된다.
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물과 백색폴리스티렌 팬텀에 의한 10 MV X-선 빔 선량계측
김종언(Jong-Eon Kim),차병열(Byung-Youl Cha),강상식(Sang-Sik Kang),박지군(Ji-Koon Park),신정욱(Jeong-Wook Sin),김소영(So-Yeong Kim),조성호(Seong-Ho Jo),손대웅(Dae-Woong Son),최치원(Chi-Won Choi),박창희(Chang-Hee Park),윤천실(Chun-Sil 대한방사선과학회(구 대한방사선기술학회) 2008 방사선기술과학 Vol.31 No.1
본 연구의 목적은 고체물등가팬텀을 사용하여 절대흡수선량을 측정할 때 물등가깊이에 비례되는 측정값을 보정하기 위한 보정인자를 구하는데 있다. 10MV X-선 빔에 대하여 백색폴리스티렌팬텀과 물팬텀에서 측정의 조건들은 선원 대 전리조 중심까지의 거리를 SAD 100cm로 고정하였고, 조사면 크기(field size)는 각각 10×10cm2, 20×20cm2를 사용하였으며, 깊이는 각각 2.3cm, 5cm, 10cm, 15cm를 사용한 것이다. 두개의 팬텀에 대하여 분당 400MU의 출력을 갖는 선형가속기로부터 100MU의 전달로 각각의 조사면 크기와 깊이들에서 3번 측정으로 취득된 전리의 평균값을 측정값으로 얻었다. 이 실험으로부터 보정인자와 TPR에서 퍼센트 편차는 각각 0.97%, 0.53% 이하를 얻었다. 따라서, 고체물등가팬텀을 사용한 절대흡수선량 측정 시에는 보정인자와 TPR에서 퍼센트 편차를 사용하여 보정을 행하면 높은 정확도를 얻을 수 있다. The purpose of this study is to get the correction factor to correct the measured values of the absolute absorbed dose proportional to the water equivalent depth. The measurement conditions in white polystyrene and water phantoms for 10MV X-ray beam are that the distance of source to center of ionization chamber is fixed at SAD 100cm, the field sizes are 10×10cm2, 20×20cm2 and the depths are 2.3cm, 5cm, 10cm, and 15cm, respectively. The mean value of ionization was obtained by three times measurements in each field size and depths after delivering 100MU from linear accelerator with output of 400MU per min to the two phantoms. The correction factor and the percentage deviation in were obtained below 0.97% and 0.53%, respectively. Therefore, we can get high accuracy by using the correction factor and the percentage deviation in in measuring the absolute absorbed dose with the solid water equivalent phantom.
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형광체 기반 X선 광 변조기를 위한 비정질 셀레늄 필름 특성
강상식,박지군,조성호,차병열,신정욱,이건환,문치웅,남상희,Kang, Sang-Sik,Park, Ji-Koon,Cho, Sung-Ho,Cha, Byung-Youl,Shin, Jung-Wook,Lee, Kun-Hwan,Mun, Chi-Woong,Nam, Sang-Hee 대한의용생체공학회 2007 의공학회지 Vol.28 No.2
PXLM(Phosphor based x-ray light modulator) has a combined structure by phosphor, photoconductor, and liquid crystal and it can realize x-ray image of high resolution in clinical diagnosis area. In this study, we fabricated a photoconductor and investigated electrical and optical properties to confirm application possibility of radiator detector of PXLM structure. As photoconductor, amorphous selenium(a-Se), which is used most in DR(Digital radiography) of direct conversion method, was used and for formation of thin film, it was formed as $20{\mu}m-thick$ by using thermal vacuum evaporation system. For a produced a-Se film, through XRD(X-ray diffraction) and SEM(Scanning electron microscope), we investigated that amorphous structure was uniformly established and through optical measurement, for visible light of 40 $0\sim630nm$, it had absorption efficiency of 95 % and more. After fabricated a-Se film on the top of ITP substrate, hybrid structure was manufactured through forming $Gd_2O_3:Eu$ phosphor of $270{\mu}m-thick$ on the bottom of the substrate. As the result to confirm electrical property of the manufactured hybrid structure, in the case of appling $10V/{\mu}m$, leakage current of $2.5nA/cm^2$ and x-ray sensitivity of $7.31nC/cm^2/mR$ were investigated. Finally, we manufactured PXLM structure combined with hybrid structure and liquid crystal cell of TN(Twisted nematic) mode and then, investigated T-V(Transmission vs. voltage) curve of external light source for induced x-ray energy. PXLM structure showed a similar optical response with T-V curve that common TN mode liquid crystal cell showed according to electric field increase and in appling $50\sim100V$, it showed linear transmission efficiency of $12\sim18%$. This result suggested an application possibility of PXLM structure as radiation detector.
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고해상도 방사선 영상을 위한 $Gd_2O_3:Eu^{3+}$ 나노 형광체 제조 및 광학적 특성
김소영,강상식,박지군,차병열,최치원,이형원,남상희,Kim, So-Yeong,Kang, Sang-Sik,Park, Ji-Koon,Cha, Byung-Youl,Choe, Chi-Won,Lee, Hyung-Won,Nam, Sang-Hee 대한의용생체공학회 2007 의공학회지 Vol.28 No.1
In this paper, we have synthesized $Gd_2O_3:Eu^{3+}$ nano phosphor particle using a low temperature solution-combustion method. We have investigated the structure and the luminescent characteristic as the sintering temperature and europium concentration. From XRD(X-ray diffraction) and SEM(scanning electron microscope) results, we have verified that the phosphor particle was fabricated a spherical shape with $30{\sim}40nm$ particle size. From the photoluminescence results, the strong peak exhibits at 611 um and the luminescent intensity depends on europium concentration. $Gd_2O_3:Eu$ fine phosphor particle has shown excellent luminescent efficiency at 5 wt% of europium concentration. The phosphors calcinated at $500^{\circ}C$ have possessed the x-ray peaks corresponding to the cubic phase of $Gd_2O_3$. As calcinations temperature increased to $700^{\circ}C$, the new monoclinic phase has identified except cubic patterns. From the luminescent decay time measurements, mean lifetimes were $2.3{\sim}2.6ms$ relatively higher than conventional bulk phosphors. These results indicate that $Gd_2O_3:Eu$ nano phosphor is possible for the operation at the low x-ray dose, therefore, the application as medical imaging detector.
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