• 대한방사선방어학회:학술대회논문집
• /
• 2009.11a
• /
• pp.182-183
• /
• 2009

• Progress in Medical Physics
• /
• v.24 no.3
• /
• pp.162-170
• /
• 2013

Dedicated single-photon emission computed tomography (SPECT) systems based on pixelated semiconductors are being developed for studying small animal models of human disease. To clarify the possibility of using a SPECT system with CdTe for a high resolution low-dose small animal imaging, we compared the quality of reconstructed images from pixelated CdTe detector to those from a small SPECT system with NaI(Tl). The CdTe detector was $44.8{\times}44.8$ mm and the pixels were $0.35{\times}0.35{\times}5$ mm. The intrinsic resolution of the detector was 0.35 mm, which is equal to the pixel size. GATE simulations were performed to assess the image quality of both SPECT systems. The spatial resolutions and sensitivities for both systems were evaluated using a 10 MBq $^{99m}Tc$ point source. The quantitative comparison with different injected dose was performed using a voxelized MOBY phantom, and the absorbed doses for each organ were evaluated. The spatial resolution of the SPECT with NaI(Tl) was about 1.54 mm FWHM, while that of the SPECT with a CdTe detector was about 1.32 mm FWHM at 30 mm. The sensitivity of NaI(Tl) based SPECT was 83 cps/MBq, while that of the CdTe detector based SPECT was 116 cps/MBq at 30 mm. The image statistics were evaluated by calculating the CNR of the image from both systems. When the injected activity for the striatum in the mouse brain was 160 Bq/voxel, the CNR of CdTe based SPECT was 2.30 while that of NaI(Tl) based SPECT was 1.85. The CNR of SPECT with CdTe was overall higher than that of the NaI(Tl) based SPECT. In addition, the absorbed dose was higher from SPECT with CdTe than those from NaI(Tl) based SPECT to acquire the same quantitative values. Our simulation results indicated that the SPECT with CdTe detector showed overall high performance compared to the SPECT with NaI(Tl). Even though the validation study is needed, the SPECT system with CdTe detector appeared to be feasible for high resolution low-dose small animal imaging.

• Journal of radiological science and technology
• /
• v.25 no.2
• /
• pp.71-75
• /
• 2002

According to this study, we can make the radiation check meter which have not supply because of high cost and import barrier and lengthen its life by means of repairing of radiation bomb and equipment. We can make better medical service. In my study, I used the photodiod, photoelectron, among semiconductor detectors which have a excellent detect capacity and are low cost and small size. I set up this equipment in June 1, 2002, used 640 mA remote operative fluorography equipment, which make the grade as capacity test. I used the standard measuring instrument which took proofs from a agency, now it was using in measuring agency. The comparative measuring instrument used in same condition. I took the standard which was gauged with a connecting measuring instrument. Using a existing unconnected measuring instrument, I compared the accuracy with new unconnected one. As a result, three score are within the standard. For the detailed analysis, I took the average of percentage average error. So standard instrument was -0.02, comparable was -0.22, and new one was -0.17. New one took a closer measured value with standard than comparable one. In more study, I think to take more accurate value. I expect that my study will be a base of measuring instrument, with low cost, supply of this instrument increase, I expect to decrease radiation bomb and maintain, repair and manager better.

• Journal of the Korean Society of Radiology
• /
• v.8 no.7
• /
• pp.383-387
• /
• 2014

In this paper, for a new detection system development with the better accurate dose evaluation and beam distribution imaging using the small field irradiation of linear accelerator, the compound semiconductor based detection sensors were fabricated and the performance evaluation was investigated. The special particle-in-binder sedimentation was used for a large area film sensor fabrication. The detection properties for high energy x-rays were investigated from a dark current, an output current, a rising time, a falling time, and response delay measurement. The experimental results, the $TiO_2$ mixed $HgI_2$ sensor showed the best electrical characteristics than $PbI_2$, PbO, pure $HgI_2$. Linearity, repeatability, and accuracy tests from LINAC were tested, the $TiO_2$ mixed $HgI_2$ sensor showed the better performance than the commercially available dosimetry devices.

• Journal of the Korean Society of Radiology
• /
• v.4 no.2
• /
• pp.21-25
• /
• 2010

Recently, various semiconductor compounds as radiation detection material have been researched for a diagnostic x-ray detector application. In this paper, we have fabricated the CdS detecton sensor that has good photosensitivity and high x-ray absorption efficiency among other semiconductor compounds, and evaluated the application feasibility by investigating the detection properties about energy range of diagnostic x-ray generator. We have fabricated the line voltage selector(LCV) for a signal acquisition and quantities of CdS sensor, and designed the voltage detection circuit and rectifying circuit. Also, we have used a relative relation algorithm according to x-ray exposure condition, and fabricated the interface board with DAC controller. Performance evaluation was investigated by data processing using ANOVA program from voltage profile characteristics according to resistive change obtained by a tube voltage, tube current, and exposure time that is a exposure condition of x-ray generator. From experimental results, an error rates were reduced according to increasing of a tube voltage and tube current, and a good properties of 6%(at 90 kVp) and 0.4%(at 320 mA) ere showed. and coefficient of determination was 0.98 with relative relation of 1:1. The error rate according to x-ray exposure time showed exponential reduction because of delayed response velocity of CdS material, and the error rate has 2.3% at 320 msec. Finally, the error rate according to x-ray dose is below 10%, and a high relative relation was showed with coefficient of determination of 0.9898.

• Journal of Radiation Protection and Research
• /
• v.38 no.3
• /
• pp.132-137
• /
• 2013

Cryogenic particle detectors have recently been adopted in radiation detection and measurement because of their high energy resolution. Many of these detectors have demonstrated energy resolutions better than the theoretical limit of semiconductor detectors. We report the development of alpha spectrometer using a micro-fabricated magnetic calorimeter coupled to a large-area particle absorber. A piece of gold foil of $2{\times}2{\times}0.05mm^3$ was glued to the paramagnetic temperature sensor made of sputtered Au:Er film to serve as an absorber for incident alpha particles. We performed experiments with 241Am source at cryogen free adiabatic demagnetization refrigerator (CF-ADR). A high energy resolution of 6.8 keV in FWHM was obtained for 5.5 MeV alpha particles.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2015.08a
• /
• pp.199.2-199.2
• /
• 2015

전이금속 칼코겐화합물(TMD)은 2차원 박막 물질로, 그래핀과 함께 차세대 사물인터넷에 적용할 수 있는 전자소자의 소재로 활용될 것으로 기대되고 있다. 특히 TMD는 그래핀과 다르게 1.2 eV 이상의 넓은 밴드갭을 지녀, 기존 실리콘 기반 반도체 소자를 대체할 차세대 물질로 각광받고 있다. TMD는 또한 실리콘 등의 3차원 반도체보다 광전효율이 뛰어나며, 이를 활용한 광전소자의 개발 및 연구가 활발히 진행되고 있다. 그러나 TMD는 그 두께가 나노미터 단위로 매우 얇아 광흡수율이 매우 떨어지는 단점이 있다. 우리는 이러한 TMD 기반 광전소자의 광흡수율을 향상시키기 위해 광전효율이 매우 뛰어난 페로브스카이트(Perovskite)를 TMD 채널 위에 덮음으로써, 이종접합 광전소자를 구현하였다. TMD 물질은 이황화 몰리브데넘($MoS_2$)을 선택하였으며, 광흡수층으로 선택한 페로브스카이트는 $MAPbI_3$을 스핀 코팅을 통해 TMD 채널 층에 접합하였다. 우리는 Photoluminescence 및 UV-Vis 측정을 통해 페로브스카이트 및 페로브스카이트/$MoS_2$ 층의 광특성을 측정하여 페로브스카이트에서 생성된 광캐리어가 확산되어 $MoS_2$에 전달되는 것을 확인하였다. 우리는 추가로 4가지 서로 다른 파장대의 레이저(520, 655, 785, 850 nm)를 이용하여 페로브스카이트 광흡수층이 있을 때와 없을 때의 $MoS_2$ 광검출기의 성능 변화를 관찰하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.06a
• /
• pp.374-374
• /
• 2010

본 연구는 Roll-to-Roll Sputtering 장비를 사용하여 제작된 Flexible ITO electrode 필름의 방사선 검출기로의 적용가능성을 알아보기 위해 기존의 Glass ITO electrode의 전기적 특성을 비교 평가하였다. 본 연구는 Flexible ITO electrode와 Glass ITO electrode을 하부전극으로 형성하고, 최근에 X-ray 변환체로 활발히 연구되고 있는 Powder 형태의 반도체물질인 HgI2 와 PbI2를 Binder와 일정한 비율로 혼합하여 3-Rolls-Miller를 사용하여 Powder를 일정한 미세크기로 만들고, 대면적 제작이 용이한 Screen-Printing method을 이용하여 시편을 제작하였다. 제작된 필름은 하부전극의 종류에 따른 X-ray 입사 후의 전기적신호의 차이를 측정하고, HgI2와 PbI2 중 Flexible ITO electrode와 더욱 효율적으로 반응하여 기존의 Glass ITO electrode를 대체할 수 있는 전극을 발견하여 진단용 의료영상의 왜곡 현상을 제거할 수 있는 Flexible 방사선 검출기의 제작의 초석을 제공하는 연구를 목적으로 한다. SEM(Scanning Electron Microscope) 통하여 반도체 물질의 결정구조와 크기를 알아보았고, 하부 전극의 종류에 따른 전기적 신호검출을 위해 제작된 필름의 암전류(Dark current) 와 민감도(Sensitivity)를 측정한 후, SNR (Signal -to- Noise)을 계산하여 평가하였다.

• The Journal of Korean Society for Radiation Therapy
• /
• v.17 no.2
• /
• pp.133-140
• /
• 2005

Purpose : This test is designed to identify the validity of treatment plan by implementing real-time dosimetry by means of dose that is absorbed into PTV and OAR when preparing doses of 3D and POP plans. Materials and Methods : In treatment. error can be calculated be comparing Exp. Dose with the actual dose, which has been converted from 'the reading value obtained by placing diode detector on the area to be measured'. Same test can be repeated using Alderson-Rando phantom. Results : Errors were found: A patient(POP plan): 197.6/199=-1.2%, B patient(3D-plan): 199.9/198.7=+0.6%, C patient: 196/200=-1.5%. In addition, considering the resulted value of measuring OAR besides target-dose for C patient showed 96/200, representing does of 47%, the purpose of protection was judged to be duly accomplished. Also it was acknowledged the resulted value of -3.7% met the targeted dose within the range of ${\pm}5%$. Conclusion : Aimed for identifying the usefulness of pre-treatment dose measurement using diode detector, this test was useful to evaluate the validity of curing because it resulted in the identification of category to be protected as well as t dose. Moreover, it is thought to have great advantage in ascertaining the dose of target, dose of which is not calculated yet. Similar to L-gram before treatment, this test is thought to be very effective so that it can bring great advantages in the aspects such as validity of curing method and post-treatment plan as well.

• Proceedings of the KIEE Conference
• /
• 2001.11c
• /
• pp.115-118
• /
• 2001

일반적으로 반도체 제조 공정은 매우 복잡하고 다양한 공정들로 구성된다. 이러한 공정 중 Stage 부분은 웨이퍼에 회로 패턴을 기입하기 위하여 웨이퍼를 미리 지정된 위치로 이송하는 공정으로 매우 높은 정밀도가 요구되고 있다. Stage에 대해서는 x, y, z축 뿐아니라 각 축에 대한 회전까지도 고려한 6축 제어가 수행되어야 한다. 본 논문에서는 stage에 대한 정밀제어의 기반기술로서 선형 BLDC 모터를 이용하여 1축 위치제어 시스템의 제어에 관하여 연구하였다. 선형 BLDC 모터의 이동 중 발생하는 추럭리플을 보상하여 제어기 설계시 선형 시스템으로 고려하여 제어기를 설계할 수 있도록 하는 방법을 제안하였으며 실험을 통하여 1[${\mu}m$]의 해상도를 갖는 위치검출 엔코더를 이용하여 5[${\mu}m$]의 정밀도를 얻을 수 있었다.