• Journal of Multimedia Information System
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• 제8권2호
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• pp.93-100
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• 2021

Under the time-varying temperature, the high-temperature radiation of forgings and the change of reflection characteristics of oxide skin on the surface of forgings lead to the difficulty of obtaining images to truly reflect the geometric characteristics of forgings. It is urgent to study the clear and reliable acquisition method of hot forging feature image under time-varying temperature to meet the requirements of visual measurement of hot geometric parameters of forgings. Based on this, this chapter first puts forward the quality evaluation method of forging feature image, which provides guarantee for the accurate evaluation of feature image quality. Furthermore, the factors that affect the image quality, such as the radiation characteristics of forgings and the photographic characteristics of cameras, are analyzed, and the imaging spectrum which can effectively suppress the radiation intensity of forgings is determined. Finally, aiming at the problem that the quality of image acquisition is difficult to guarantee due to the drastic change of radiation intensity of forgings under time-varying temperature, an image acquisition method based on minimum signal-to-noise ratio (SNR) based laser light intensity adaptation is proposed, which significantly improves the definition of feature light strips in forging images at high temperature, and finally realizes the clear acquisition of feature images of large-scale hot forging under time-varying temperature.

• Imaging Science in Dentistry
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• 제54권2호
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• pp.159-169
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• 2024

Purpose: The aim of this study was to evaluate the influence of different cone-beam computed tomography (CBCT) acquisition protocols on reducing the effective radiation dose while maintaining image quality. Materials and Methods: The effective dose emitted by a CBCT device was calculated using thermoluminescent dosimeters placed in a Rando Alderson phantom. Image quality was assessed by 3 experienced evaluators. The relationship between image quality and confidence was evaluated using the Fisher exact test, and the agreement among raters was assessed using the kappa test. Multiple linear regression analysis was performed to investigate whether the technical parameters could predict the effective dose. P-values<0.05 were considered to indicate statistical significance. Results: The optimized protocol (3 mA, 99 kVp, and 450 projection images) demonstrated good image quality and a lower effective dose for radiation-sensitive organs. Image quality and confidence had consistent values for all structures (P<0.05). Multiple linear regression analysis resulted in a statistically significant model. The milliamperage (b=0.504; t=3.406; P=0.027), kilovoltage peak (b=0.589; t=3.979; P=0.016) and number of projection images (b=0.557; t=3.762; P=0.020) were predictors of the effective dose. Conclusion: Optimized CBCT acquisition protocols can significantly reduce the effective radiation dose while maintaining acceptable image quality by adjusting the milliamperage and projection images.

• 방사선산업학회지
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• 제8권3호
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• pp.147-153
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• 2014

This paper describes a large area CMOS image sensor module Implementation using the precision align inspection program. This work is needed because wafer cutting system does not always have high precision. The program check more than 8 point of sensor edges and align sensors with moving table. The size of a $2{\times}1$ butted CMOS image sensor module which except for the size of PCB is $170mm{\times}170mm$. And the pixel size is $55{\mu}m{\times}55{\mu}m$ and the number of pixels is $3,072{\times}3,072$. The gap between the two CMOS image sensor module was arranged in less than one pixel size.

• Journal of Radiation Protection and Research
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• 제37권3호
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• pp.146-148
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• 2012

The use of GEANT4 simulation toolkit has increased in the radiation medical field for the design of treatment system and the calibration or validation of treatment plans. Moreover, it is used especially on calculating dose simulation using medical data for radiation therapy. However, using internal visualization tool of GEANT4 detector constructions on expressing dose result has deficiencies because it cannot display isodose line. No one has attempted to use this code to a real patient's data. Therefore, to complement this problem, using the result of gMocren that is a three-dimensional volume-visualizing tool, we tried to display a simulated dose distribution and isodose line on medical image. In addition, we have compared cross-validation on the result of gMocren and GEANT4 simulation with commercial radiation treatment planning system. We have extracted the analyzed data of dose distribution, using real patient's medical image data with a program based on Monte Carlo simulation and visualization tool for radiation isodose mapping.

• 대한방사선기술학회지:방사선기술과학
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• 제38권4호
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• pp.483-489
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• 2015

현대의 의료용 방사선 발생장치는 영상을 저장하고 전송하기 위해 의료영상 표준규격으로 Digital image communications in medicine(DICOM)을 채택하고 있다. DICOM 규격에서는 피폭선량 정보 표시를 위해 DICOM dose Structured Report(DICOM dose SR)를 표준으로 제정하여 사용하고 있다. 이와 더불어 DICOM Modality Performed Procedure Step(DIOCM MPPS) 정보와 DICOM tag 정보에서도 부분적인 피폭선량 정보를 표시하고 있다. 본 연구에서는 DICOM과 관련된 피폭선량정보 표시방법에 대해 고찰하고 의료정보 시스템간의 상호연동 테스트를 위한 Integrating the Healthcare Enterprise(IHE)의 Radiation Exposure Monitoring(REM) 프로파일에 대해 살펴보았다. 의료기관에서 의료방사선피폭선량정보에 대한 품질관리를 위해서는 DICOM 정보에서 표시되는 피폭선량 정보형식에 대한 이해가 반드시 수반되어야 하고 장비도입 단계에서 관련 규격에 대한 검토가 이루어져야 한다.

• 한국의학물리학회지:의학물리
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• 제34권1호
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• pp.14-14
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• 2023

• 방사선산업학회지
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• 제17권3호
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• pp.233-238
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• 2023

This study was conducted to confirm the safety of the operator's radiation exposure in the micro PET-CT image acquisition experiment using the ¹⁸F-FDG. The usage of ¹⁸F-FDG and the exposure dose of handlers were measured at University B in Metropolitan City A, which uses ¹⁸F-FDG for micro PET-CT image acquisition. As a result of the measurement, the exposure dose is far below the effective dose limit of radiation workers, 50 mSv per year, and the equivalent dose limit of 500 mSv per year for hands, feet, and skin. has been measured Since these exposure doses can be further increased according to the number of times of use of ¹⁸F-FDG, it is judged that the exposure dose compared to the handling amount of ¹⁸F-FDG shown in this study can be used as reference data. In addition, as changed environments such as the use of materials other than unopened RI are occurring in education and research environments, such as the use of ¹⁸F-FDG at University B, radiation exposure with more interest in safety management by checking the factors of radiation exposure of the handler concerned We will always do our best to reduce it.

• 한국방사선학회논문지
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• 제3권1호
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• pp.5-9
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• 2009

디지털 방사선 검출기의 주된 연구동향은 영상의 해상도 향상, 대면적화, 동영상 구현 등${\cdots}$ 이라 할 수 있다. 이런 연구는 방사선 변환과정에 따라 크게 직접변환 방식과 간접 변환 방식으로 나눌 수 있으며 각각 고유한 장단점을 내포하고 있다. 간접변환 방식의 경우 형광체의 사용으로 인한 Light scattering 문제로 해상력의 저하 그리고 직접방식의 경우는 낮은 system 안정성과 동영상 구현의 어려움 등이 대표적이라 할 수 있다. 이런 문제를 해결하기 위한 연구로써 액정을 이용한 엑스선 검출기 연구가 진행되었으나 그 구조의 특성상 균일한 액정의 주입이 어려워 제작에 있어 많은 어려움이 있다. 따라서 본 논문에서는 기존의 문제점을 해결할 수 있는 구조를 제안하고 이를 Simulation 통해 제안된 구조의 가능성을 검토해 보았다.

• Imaging Science in Dentistry
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• 제52권3호
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• pp.283-288
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• 2022

Purpose: This study was conducted to measure the radiation exposure and image quality of various cone-beam computed tomography (CBCT) machines under common clinical conditions and to analyze the correlation between them. Materials and Methods: Seven CBCT machines used frequently in clinical practice were selected. Because each machine has various sizes of fields of view (FOVs), 1 large FOV and 1 small FOV were selected for each machine. Radiation exposure was measured using a dose-area product (DAP) meter. The quality of the CBCT images was analyzed using 8 image quality parameters obtained using a dental volume tomography phantom. For statistical analysis, regression analysis using a generalized linear model was used. Results: Polymethyl-methacrylate (PMMA) noise and modulation transfer function (MTF) 10% showed statistically significant correlations with DAP values, presenting positive and negative correlations, respectively (P<0.05). Image quality parameters other than PMMA noise and MTF 10% did not demonstrate statistically significant correlations with DAP values. Conclusion: As radiation exposure and image quality are not proportionally related in clinically used equipment, it is necessary to evaluate and monitor radiation exposure and image quality separately.

• Journal of Radiation Protection and Research
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• 제34권1호
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• pp.25-30
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• 2009

Micro-columnar CsI(Tl) is the most popular scintillator material which is used for many indirect digital X-ray imaging detectors. The light scattering at the surface of micro-columnar CsI(Tl) scintillator was studied to find the correlation between the surface roughness and the resultant image resolution of indirect X-ray imaging detectors. Using a commercially available optical simulation program, Light Tools, MTF (Modulation Transfer Function) curves of the CsI(Tl) film thermally evaporated on glass substrate with different thickness were calculated and compared with the experimental estimation of MTF values by the edge X-ray image method and CCD camera. It was found that the standard deviation value of Gaussian scattering model which is determined by the surface roughness of micro-columns could certainly change the MTF value of image sensors. This model and calculation methodology will be beneficial to estimate the overall performance of indirect X-ray imaging system with CsI(Tl) scintillator film for optimum design depending on its application.