The objective of this project is to develop a detector with better resolution and greater sensitivity than existing X-ray film, thus permitting both earlier discovery of tumors and reduced exposure of patients to ionizing radiation. the system will be based upon gas microstrip detectors (GMDs), a new technology developed by the Department of Energy for high energy physics research. It will detect, with 100 percent efficiency, the characteristic X-rays produced by standard molybdenum targets, and will do so with very high resolution, about 60 microns (roughly half the diameter of a human hair). In Phase I, Spire will use conventional microelectronic manufacturing equipment to fabricate a small GMD, approximately 10 cm by 10 cm, and test its resolution at Texas A&M University; through its work on a GMD- based detector for the Superconducting Supercollider, Texas A&M has the background and experience to quickly and effectively evaluate Spire's design. Phase II will follow with fabrication of a full-scale prototype whose ability to produce high-resolution, low-dose images will be demonstrated by with an ACR Accreditation Phantom.