Interlaced versus progressive readout of television cameras for digital radiographic acquisitions

A comparison was made of two methods for reading the TV camera target for digital radiographic acquisition, interlaced and progressive readout. Experiments were performed with a plumbicon TV camera to measure x-ray exposure requirements and resolution capabilities after readout for the two modes. Real time digital (30 frames per second, 256(2) matrix) and single-frame electrocardiogram gated images of the contrast-filled coronary arteries in a dog were acquired with both formats. Results demonstrate a reduction in patient exposure of up to four times for single-frame progressive readout images over interlaced acquisition for static images of comparable quality. Imaging of rapid motion objects (e.g., coronary arteries) with interlaced TV scanning results in "scalloping" of edges and resolution degradation. The short pulse width capability of progressive readout eliminates motion blurring and preserves object detail. Progressive readout is the preferred mode of TV camera readout for most digital radiographic applications due to more flexible x-ray techniques, superior images, and total utilization of the input x-ray flux for lower patient exposure.