Evaluation of video capture equipment for secondary image acquisition in the PACS

There are many cases in which picture archiving and communication systems (PACS) are built with old-type existing modalities with no DICOM output. One of the methods for interfacing them to the PACS is to implement video capture (/ frame grabber) equipment. This equipment takes analog video signal output from medical imaging modalities, and amplitude of the video signal is A/D converted and supplied to the PACS. In this report, we measured and evaluated the accuracy at which this video capture equipment could capture the image. From the physical evaluation, we found the pixel values of an original image and its captured image were almost equal in gray level from 20%-90%. The change in the pixel values of a captured image was +/-3 on average. The change of gray level concentration was acceptable and had an average standard deviation of around 0.63. As for resolution, the degradation was observed at the highest physical level. In a subjective evaluation, the evaluation value of the CT image had a grade of 2.81 on the average (the same quality for a reference image was set to a grade of 3.0). Abnormalities in heads, chests, and abdomens were judged not to influence diagnostic accuracy. Some small differences were seen when comparing captured and reference images, but they are recognized as having no influence on the diagnoses.