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Gamma-PF 보드를 이용한 아날로그 감마카메라의 디지털화 연구
김희중,소수길,봉정균,김한명,김장휘,주관식,이종두,Kim, Hui-Jung,So, Su-Gil,Bong, Jeong-Gyun,Kim, Han-Myeong,Kim, Jang-Hwi,Ju, Gwan-Sik,Lee, Jong-Du 대한의용생체공학회 1998 의공학회지 Vol.19 No.4
아날로그 감마카메라에 비해 디지털 카메라는 Q.C가 편리하고, Calibration과 조작이 매우 쉬운 장점들을 갖고 있어 영상 질을 향상시킬 뿐만 아니라 진단의 정확도를 높일 수 있다. 더욱이, 디지털 카메라로 획득한 디지털 영상은 PACS(Picture Archiving and Communication System) 뿐만 아니라 원격진료에도 활용될 수 있다. 그러나, 많은 병원들이 아직도 아날로그 카메라를 사용하고 있고 이들을 디지털 카메라로 대체하기는 어려운 상황에 있다. 본 연구는 아날로그 감마카메라를 디지털화 할 수 있는지의 가능성을 보는 것이었다. 카메라를 디지털화 한 후 균일도 계수능력 등의 물리적 특성을 측정하였다. 임상에서의 사용 가능성을 보기 위해 아날로그 시스템과 디지털 시스템을 동시에 연결하여 임상 데이터들을 획득하였다. 이들의 결과는 임상환경에서 아날로그 카메라를 디지털화 하 수 있다는 가능성을 보여주었다. Digital gamma camera has many advantages over analog gamma camera. These include convenient quality control, easy calibration and operation, and possible image quantitation which results in improving diagnostic accuracies. The digital data can also be utilized for telemedicine and picture archiving and communication system. However, many hospitals still operate analog cameras and have difficult situation to replace them with digital cameras. We have studied a feasibility of digitalizing an analog gamma camera into a digital camera using Gamma-PF interface board. The physical characteristics that we have measured are spatial resolution, sensitivity, uniformity, and image contrast. The patient's data obtained for both analog and digital camera showed very similar image quality. The results suggest that it may be feasible to upgrade an analog camera into a digital gamma camera in clinical environments.
Comparison and Evaluation of JPEG and JPEG2000 in Medical Images for CR (Computed Radiography)
김희중,Dae-Hong Kim,Chang-Lae Lee,Hyo-Min Cho,박혜석,A-Ram Yoo,Young-Sub Lee 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.56 No.3
Computed radiography (CR) images will require large storage facilities and long transmission times for picture archiving and communications system (PACS) implementation. The American College of Radiology and National Equipment Manufacturers Association (ACR/NEMA) group is planning to adopt a JPEG2000 compression algorithm in the Digital Imaging and Communications in Medicine (DICOM) standard for better utilization of medical images. The purpose of this study was to evaluate and compare the results of JPEG and JPEG2000 compressions in medical images. We applied various compression ratios of JPEG and JPEG2000 to chest, abdomen, and hand images obtained using the AGFA CR (Computed Radiography) system (AGFA MD-4.0, BELGIUM)and the FUJI CR system (FCR 9000C, JAPAN). A quantitative evaluation was carried out using the PSNR (peak signal to noise ratio), which is a commonly used measure for the evaluation of reconstructed images and measures how the reconstructed images differ from the original images. In the JPEG and JPEG2000 comparison for compression ratios up to 60:1, the PSNR value showed less than 30 dB in accordance with CR modalities and image regions in JPEG compression whereas JPEG2000 showed more than 30 dB in the same compression ratios for both AGFA and FUJI CR images. As the compression ratios were increased to 200:1, use of the JPEG2000 algorithm showed over 30 dB of the PSNR value in accordance with CR modalities and image regions. In general,when the PSNR value gets greater than or equal to 30 dB, the quality of the processed image is acceptable. Nevertheless, the PSNR value cannot absolutely stand for the quality in terms of perceptibility. The artifact of blockiness is found to be visible not only for the AGFA CR image at 40:1 but also for the FUJI CR image at 40:1 and 60:1 in JPEG compression while no significant artifact were observed in the JPEG2000 compressed image up to 200:1. In conclusion, JPEG2000appeared to be a more effective method of compression than JPEG in medical imaging applications based on the PSNR value, ROC studies may be needed to establish whether these applications are suitable for real clinical situations requiring diagnostic accuracy.