Early detection and routine clinical screening represent the first line of defense for preventing fatalities from cancer, a disease, which claimed 551,833, lives in the U.S. during the year 2000. Significant advances have been made in the medical imaging of tumors; however, many of these techniques are too expensive to be implemented for routine screening. Diffuse optical tomography (DOT) promises to provide a low-cost method for routine, non-invasive cancer screening. Unfortunately, the absence of appropriate imaging technologies for the high-frequency modulation techniques employed by DOT severely limits the spatial resolution and constrains the diagnostic value of DOT. This program resolves these limitations by developing a fully integrated, nearlR digital camera chip, which is an application specific integrated circuit (ASIC), that counts photons using Geiger avalanche photodiodes. This all-digital, CMOS (complementary-symmetry metal-oxide-semiconductor) imaging technology fulfills the demanding requirements for providing high-resolution DOT images. In Phase I, we will explore appropriate fabrication architectures for the ASIC and fabricate prototype pixel elements, along with the critical circuit components needed to support the pixel element. We will test the prototype devices and compare their measured performance to the initial design specifications.
