EVALUATION OF A LOW-DOSE DIGITAL X-RAY SYSTEM WITH IMPROVED SPATIAL-RESOLUTION

We present results from an evaluation of a significantly improved vers ion of the Siberian Digital Radiographic Device (SDRD). The SDRD is al ready in clinical use in Novosibirsk and Moscow where it produces imag es of high diagnostic value at considerably lower doses than conventio nal film-screen combinations. It uses a fast multiwire proportional ch amber with highly parallel readout as a detector. Improvements in the readout system have given a reduction by a factor of two in the pixel size. We have used well established methods to compare imaging perform ance of the new SDRD with the old version as well as with a film-scree n combination used in routine clinical practice in the UK. At the same level of exposure the threshold contrast for objects of the order of the pixel size is two times better for the new SDRD than for the old o ne, and the minimum size of objects visible in the image is two times smaller (0.25 mm) for the new system than for the old SDRD (0.5 mm).