CCD camera for dual-energy digital subtraction angiography

A motion immune dual-energy subtraction technique in which x-ray tube voltage and beam filtration were switched at 30 Hz between 60 kVp (2.0 mm Al filter) and 120 kVp (2.00 mm Al +2.5 mm Cu filter) was previously reported. In this study the effects of camera lag on the dual energy iodine signal is investigated. The temporal lag of the lead oxide vidicon tested reduced the dual-energy iodine signal by a factor of 2.3, as compared to a mode that included 4 scrub frames between low- and high-energy images, for an iodine phantom with thicknesses of 0-86.0 mg/cm(2), imaged over a 15 cm thick Lucite phantom. On the other hand, the Charge-Coupled Device (CCD) camera has inherently no temporal lag and its versatile scanning characteristics make it near ideal for dual-energy DSA. The CCD camera eliminates the reduction of dual-energy iodine signal, since it does not mix low- and high-energy image data. Another benefit of the CCD camera is that the separation time between low and high-energy images is not limited to the frame period, as is the lead oxide vidicon; and as small as a 5-msec time difference is possible. The short time interval between low and high-energy images minimizes motion misregistration artifacts. Due to these advantages, the CCD camera significantly improves the utility of dual-energy DSA.