• Nuclear Engineering and Technology
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• v.55 no.10
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• pp.3700-3708
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• 2023

The stochastic origin ensembles method with resolution recovery (SOE-RR) has been proposed to reconstruct proton-induced prompt gammas (PGs), and the reconstructed PG image was used for range verification. However, due to low detection efficiency, the number of valid events is low. Such a low-count condition can degrade the accuracy of the SOE-RR method for proton range verification. In this study, we proposed two strategies to improve the reconstruction of the SOE-RR algorithm for low-count PG imaging. We also studied the number of iterations and repetitions required to achieve reliable range verification. We simulated a proton beam (10⁸ protons) irradiated on a water phantom and used a two-layer Compton camera to detect 4.44-MeV PGs. Our simulated results show that combining the SOE-RR algorithm with restricted volume (SOE-RR-RV) can reduce the error of the estimation of the Bragg peak position from 5.0 mm to 2.5 mm. We also found that the SOE-RR-RV algorithm initialized using a back-projection image could improve the convergence rate while maintaining accurate range verification. Finally, we observed that the improved SOE-RR algorithm set for 60,000 iterations and 25 repetitions could provide reliable PG images. Based on the proposed reconstruction strategies, the SOE-RR algorithm has the potential to achieve a positioning error of 2.5 mm for low-count PG imaging.

• Nuclear Medicine and Molecular Imaging
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• v.41 no.1
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• pp.68-69
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• 2007

A 44-year-old female underwent three-phase bone scintigraphy for an evaluation of right hip joint pain. The blood-flow and blood-pool images show a pelvic blush with a photopenic center (doughnut) prior to bladder filling. On the three hour delayed image, the pelvic uptake disappeared. The scintigraphic findings indicated the possibility of an early pregnancy. However, plain radiography demonstrated an intrauterine device. A uterine doughnut developed as a result of photon attenuation of intrauterine device.

• Journal of the Optical Society of Korea
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• v.7 no.4
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• pp.234-239
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• 2003

Objective methods to assess quantitatively port wine stain (PWS) blanching in response to laser therapy are needed to improve laser therapeutic outcome. Previous studies have attempted to assess objectively PWS color based on point measurement devices. To date, these approaches have typically been limited by a number of factors such as small test area and need for contact. To address these issues, a polarization spectral imaging system and an image analysis method have been developed to evaluate quantitatively erythema and melanin content distribution in skin. The developed polarization spectral imaging system minimizes artifacts such as glaring, shadowing, and non-uniform illumination that interfere with image fidelity. Furthermore, the image analysis method has been employed to get images of skin melanin and erythema indices from the acquired color images for quantitative analysis. Finally, using PWS patient color image, the effectiveness in laser treatment of PWS was evaluated by calculating relative erythema index image that is the relative erythema index of PWS region to the normal region. The developed device and analysis method appears to be a simple and effective method for quantitative analysis of PWS blanching.

• Korean Journal of Digital Imaging in Medicine
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• v.3 no.1
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• pp.72-73
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• 1997

Medical imaging device에서 이미지 정보의 교환은 PACS의 성공을 결정짓는 중요한 요소이다. 즉 이미지 정보를 획득한다는 것은 네트워크상에서 정보를 신속 정확히 얻을 수 있다는 장점을 말한다. 더욱 중요한 것은 이미지파일의 호환성이다. 의료영상저장전달시스템 즉 PACS는 병원의 모든 정보와 서로 연동될 수 있어야 한다. 데이타 통합과 시스템의 안정성은 PACS에 있어서 가장 중요한 필수요건이다. 위에 언급한 요구조건들을 모두 만족시키기 위해서는 시스템 상호간을 네트워크할 수 있는 공통의 통합 프로토콜이 필요하다. 이와같은 문제를 해결하기 위해서 The American College of Radiology(ACR)과 National Electrical Manufacturers Association(NEMA)는 1983년초에 업체간의 장비공유와 방사선 실무자들의 통합되는 프로토클을 제정하기 위해 위원회를 설립하였다. 여기서 제정된 프로토콜을 DICOM이라 정하였다. DICOM의 역사적 배경, 의미, 필요성과 시스템상에서 어떻게 역활해왔는가와 DICOM을 통한 PACS시스템의 실제 활용예에 대하여 알아보겠다.

• Clinical and Experimental Pediatrics
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• v.57 no.7
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• pp.297-303
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• 2014

Transcatheter closure of atrial septal defects has become a popular procedure. The availability of a preprocedural imaging study is crucial for a safe and successful closure. Both the anatomy and morphology of the defect should be precisely evaluated before the procedure. Three-dimensional (3D) echocardiography and cardiac computed tomography are helpful for understanding the morphology of a defect, which is important because different defect morphologies could variously impact the results. During the procedure, real-time 3D echocardiography can be used to guide an accurate closure. The safety and efficiency of transcatheter closures of atrial septal defects could be improved through the use of detailed imaging studies.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.1
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• pp.29-36
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• 2014

In this paper, a novel MBE (Model Based target size Estimator) is presented for SDIIR (Strap Down Imaging Infrared) seekers. The target tracking requires the target size information for which residual range between target and missile should be provided. Unfortunately, in general, the missile with passive sensor such as IIR (Imaging Infrared), CCD (Coupled Charging Device) cannot obtain range information. To overcome the problem, the proposed method enables the SDIIR seeker to estimates target size by using target size model and track the target. The performance of proposed method is tested at IIR target tracking of target intercept scenario. The experiment results show that the proposed algorithm has the relatively good performance.

• Electronics and Telecommunications Trends
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• v.33 no.6
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• pp.81-93
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• 2018

Metamaterials are artificial media that can control the properties of waves at will. Active photonic metadevice technologies cover the device and material technologies that control the visible and IR light through an external signal (mainly an electrical signal). The application areas of active photonic metadevices are tremendous for example holography, active HOE, bio imaging, IR imaging, telecommunication, and optoelectronic devices. In this paper, the technical trends and prospects of active metamaterials, active meta holography, active meta devices, nano-optical telecommunication devices, and IR imaging meta devices are reviewed.

• Current Optics and Photonics
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• v.7 no.2
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• pp.176-182
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• 2023

Optical coherence tomography (OCT) is being developed to guide various ophthalmic surgical procedures. However, the high cost of the intraoperative OCT system limits its availability mostly to the largest hospitals and healthcare systems. In this paper, we present a design and evaluation of a low-cost intraoperative common-path free-hand scanning OCT system. The lensed fiber imaging probe is designed and fabricated for intraocular use and the free-hand scanning algorithm that could operate at a low scanning speed was developed. Since the system operates at low frequencies, the cost of the overall system is significantly lower than other commercial intraoperative OCT systems. The assembled system is characterized and shows that it meets the design specifications. The handheld OCT imaging probe is tested on multilayer tape phantom and ex-vivo porcine eyes. The results show that the system could be used as an intraoperative intraocular OCT imaging device.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.2_2
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• pp.437-443
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• 2024

The purpose of radiological Dispersal Device(RDD) is to kill people by explosives and to cause radiation exposure by dispersing radioactive materials. And It is a form of explosive that combines radioactive materials such as Co-60 and Ir-192 with improvised explosives. In this study, we tested and evaluated whether it was possible to read the internal structure of an explosive using X-rays in a radioactive explosive situation. The improvised explosive device was manufactured using 2 lb of model TNT explosives, one practice detonator, one 9V battery, and a timer switch in a leather briefcase measuring 41×35×10 cm³. The radioactive material used was the Co-60 source used in the low-level gamma ray irradiation device operated at the Advanced Radiation Research Institute of the Korea Atomic Energy Research Institute. The radiation dose used was gamma ray energy of 1.17 MeV and 1.33 MeV from a Co-60 source of 2208 Ci. The dose rates are divided into 0.5, 1, 2, and 4 Gy/h, and the exposure time was divided into 1, 3, 5, and 10 minutes. Co-60 source was mixed with the manufactured explosive and X-ray image reading was performed. As a result of the experiment, the X-ray image appeared black in all conditions divided by dose rate and time, and it was impossible to confirm the internal structure of the explosive. This is because γ-rays emitted from radioactive explosives have higher energy and stronger penetrating power than X-rays, so it is believed that imaging using X-rays is limited By blackening the film. The results of this study are expected to be used as basic data for research and development of X-ray imaging that can read the internal structure of explosives in radioactive explosive situations.

• The Journal of Korean Society for Radiation Therapy
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• v.25 no.1
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• pp.57-67
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• 2013

Purpose: Replacing the film which used to be used for checking the set-up of the patient and dosimetry during radiation therapy, more and more EPID equipped devices are in use at present. Accordingly, this article tried to evaluated the accuracy of the position check-up and the usefulness of dosimetry during the use of an electronic portal imaging device. Materials and Methods: On 50 materials acquired with the search of Korea Society Radiotherapeutic Technology, The Korean Society for Radiation Oncology, and Pubmed using "EPID", "Portal dosimetry", "Portal image", "Dose verification", "Quality control", "Cine mode", "Quality - assurance", and "In vivo dosimetry" as indexes, the usefulness of EPID was analyzed by classifying them as history of EPID and dosimetry, set-up verification and characteristics of EPID. Results: EPID is developed from the first generation of Liquid-filled ionization chamber, through the second generation of Camera-based fluoroscopy, and to the third generation of Amorphous-silicon EPID imaging modes can be divided into EPID mode, Cine mode and Integrated mode. When evaluating absolute dose accuracy of films and EPID, it was found that EPID showed within 1% and EDR2 film showed within 3% errors. It was confirmed that EPID is better in error measurement accuracy than film. When gamma analyzing the dose distribution of the base exposure plane which was calculated from therapy planning system, and planes calculated by EDR2 film and EPID, both film and EPID showed less than 2% of pixels which exceeded 1 at gamma values (r%>1) with in the thresholds such as 3%/3 mm and 2%/2 mm respectively. For the time needed for full course QA in IMRT to compare loads, EDR2 film recorded approximately 110 minutes, and EPID recorded approximately 55 minutes. Conclusion: EPID could easily replace conventional complicated and troublesome film and ionization chamber which used to be used for dosimetry and set-up verification, and it was proved to be very efficient and accurate dosimetry device in quality assurance of IMRT (intensity modulated radiation therapy). As cine mode imaging using EPID allows locating tumors in real-time without additional dose in lung and liver which are mobile according to movements of diaphragm and in rectal cancer patients who have unstable position, it may help to implement the most optimal radiotherapy for patients.