Kenji Okusako

Development and evaluation of a digital subtraction angiography system using a large-area flat panel detector

We developed prototype Digital Subtraction Angiography (DSA) System with a new large area FPD. Dynamic range, MTF, Contrast ratio and line noise were much improved. The improved FPD is a scintillator-type detector, and has a 40 x 30 cm active area, 2048 x 1536 matrix with 194um pixel pitch. The Prototype DSA system has two x-ray detectors, the FPD and the I.I.-CCD camera, and we can choose them on demand. All images captured from both detectors at 3 frames/sec in DSA mode and 30 frames/sec in Fluoroscopy mode are forwarded to our image-processing unit. We applied the new DSA system to more than 150 studies and compared the results with images from the I.I.-CCD. In DSA mode, FPD System, which has a wide dynamic range, large detecting area, and good contrast ratio yielded superior angiogram images compared with the I.I-CCD system. In Fluoroscopy mode, we improved line noise and increased the contrast of catheters and guide wires with a new image processing technique. With these improvements, the image quality of the FPD System is superior to the I.I.-CCD system at the exposure range of over 2uR/frame (17.4 nGy/frame).

Basic evaluation of physical characteristics and clinical study of new digital subtraction angiography system with a large-area flat-panel detector

Authors could have a clinical experience to use an angiographic system incorporating FPD. This system possesses both FPD and I.I.-CCD detectors and is capable of conducting imaging in the same geometry for both detectors. We made measurement of basic physical characteristics of this system and visual evaluation using arteriographies of lower limbs processed by IVDSA, and confirmed that FPD is an excellent detector in angiographic examination. In the foreseeable future, angiographic system will be replaced by FPD system.