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- 주제어 : X-ray imaging devices (검색결과 5 건)
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Whang, Joo-Ho,Chung, Jin-Bum,Kim, Tae-Woo Korean Nuclear Society 2001 Nuclear Engineering and Technology Vol.33 No.5
Optimum characteristics of digital X-ray sensor components were analyzed to develop intra- oral dental digital X-ray image sensor using indirect method. Parametric analysis was carried out to optimize the phosphor thickness and the fiber optic plate (FOP) coupling to charge coupled device (CCD). X-ray absorption and light diffusion in the phosphor layer were analyzed by the Monte Carlo method. Real time X-ray image was obtained with prototype X- ray image sensor using general CCD camera with 1∼10 Ip/mm resolution. It has been previously shown that large resolution degradation in X-ray images was caused by miss alignment of FOP to CCD and optical adhesive selection. In this study, we reported that X-ray image quality was greatly improved by using optimized characteristics of alignment device and phosphor thickness.
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Hyun-Jin Kim,Jun-Seok Lee,Dong-hoon Gwak,Chang-Won Park,Chunil Lim,Seung-Youl Lee 한국자기학회 2022 Journal of Magnetics Vol.27 No.4
This study verifies the feasibility and optimal conditions for using a general-purpose x-ray imaging device with a relatively large detector and excellent image quality compared to dental x-ray imaging devices according to international standards. The dental material test specimens were produced in the form of disks from four companies with different radiopacity, and aluminum step wedges was manufactured according to ISO 13116. In order to find the optimal irradiation conditions for general X-ray imaging devices, the distance between the target and the tube was fixed at 700 mm, and the exposure time was fixed at 100 ms. And the tube voltage was 50, 60, 70 kV and the tube current was changed to 40, 80, and 160 mA. As a result, it was sufficient to use generalpurpose X-ray imaging devices, and the best results were obtained under the optimal conditions of 60 kV and 40 mA.
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Liu, Huajun,Dong, Yongqi,Cherukara, Mathew J.,Sasikumar, Kiran,Narayanan, Badri,Cai, Zhonghou,Lai, Barry,Stan, Liliana,Hong, Seungbum,Chan, Maria K. Y.,Sankaranarayanan, Subramanian K. R. S.,Zhou, Hua American Chemical Society 2018 ACS NANO Vol.12 No.5
<P>Memristive devices are an emerging technology that enables both rich interdisciplinary science and novel device functionalities, such as nonvolatile memories and nanoionics-based synaptic electronics. Recent work has shown that the reproducibility and variability of the devices depend sensitively on the defect structures created during electroforming as well as their continued evolution under dynamic electric fields. However, a fundamental principle guiding the material design of defect structures is still lacking due to the difficulty in understanding dynamic defect behavior under different resistance states. Here, we unravel the existence of threshold behavior by studying model, single-crystal devices: resistive switching requires that the pristine oxygen vacancy concentration reside near a critical value. Theoretical calculations show that the threshold oxygen vacancy concentration lies at the boundary for both electronic and atomic phase transitions. Through <I>operando</I>, multimodal X-ray imaging, we show that field tuning of the local oxygen vacancy concentration below or above the threshold value is responsible for switching between different electrical states. These results provide a general strategy for designing functional defect structures around threshold concentrations to create dynamic, field-controlled phases for memristive devices.</P> [FIG OMISSION]</BR>
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이도병,서승준,최현우,고철우,김종기 대한방사선과학회 2020 방사선기술과학 Vol.43 No.4
Examination with medical radiography is the most significant advances in medicine in the 21st century. Diagnostic imaging occupies an important position in all medical subjects, surgical and internal medicine, including radiology, orthopedics, and neurosurgery. However, the invention associated with conventional radiography devices has focused only on emphasizing the efficient aspects of the examination or obtaining clearer images without considering the age and disease-induced constraints of the patient's posture. The newly developed X-ray aids to solve this problem can effectively perform X-ray imaging of children's who have difficulty communicating and controlling. It is also thought to be a good way to provide accurate imaging information and minimize radiation exposure for children.
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방사선치료시 전자포털영상장치를 이용한 잡음전력스펙트럼 방법론 측정비교
손순룡(Soon Yong Son),최관우(Kwan Woo Choi),정회원(Hoi Woun Jeong),권경태(Kyung Tae Kwon),김기원(Ki Won Kim),이영아(Young Ah Lee),손진현(Jin Hyun Son),민정환(Jung Whan Min) 대한방사선과학회 2016 방사선기술과학 Vol.39 No.1
잡음전력스펙트럼 (noise power spectrum, NPS)는 noise 진폭의 측정과 균일한 방사선 영역으로부터 획득된 영상의 품질에 가장 일반적인 방법 중 하나이다. 이 연구의 목적은 megavoltage X-ray 에너지를 사용하여 다른 잡음전력스펙트럼 방법론들을 비교하는 것이다. 진단 영역에서의 잡음전력스펙트럼 평가 방법들은 국제 전기 규격 international electro-technical commission (IEC 62220-1) 기준을 사용하여 치료 영역에 적용되었다. 우리가 사용한 전자포털영상장치(electronic portal imaging device, EPID)는 Varian TrueBeamTM, Siemens BEAMVIEWPLUS, Elekta iViewGT 그리고 Varian ClinacR iX aS1000이었다. 잡음전력스펙트럼의 관심영역을 측정하기 위해, 우리는 겹침 (overlapping), 비겹침 (non-overlapping), 평탄도 (flatness), 반음영 (penumbra) 4가지 인자를 사용하였다. 결과적으로는 Siemens BEAMVIEWPLUS, Varian TrueBeamTM flattening filter, Varian ClinacR iX aS1000, Varian TrueBeamTM flattening filter free에서의 잡음 (noise) 분포는 기존의 첫번째, 두번째, 세번째 실험방법보다는 Elekta iViewGT보다 현격하게 높은 noise 분포가 나타남을 알 수 있다. 이번 연구는 다양한 인자들이 잡음전력스펙트럼의 megavoltage imaging (MVI)영상에서 MVI영역에서 잡음전력스펙트럼의 기준의 방법론으로 사용되어질 수 있다는 것을 보여주었다. 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 Electro-technical Commission standard (IEC 62220-1). Various radiation therapy (RT) devices such as TrueBeamTM(Varian), BEAMVIEWPLUS(Siemens), iViewGT(Elekta) and ClinacR iX (Varian) were used. In order to measure the region of interest (ROI) of the NPS, we use the following four factors: the overlapping impact, the non-overlapping impact, the flatness and penumbra. As for NPS results, iViewGT(Elekta) had the higher amplitude of noise, compared to BEAMVIEWPLUS (Siemens), TrueBeamTM(Varian) flattening filter, ClinacRiXaS1000(Varian) and TrueBeamTM(Varian) flattening filter free. 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 methodologies control in MVI.
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