MOSFET dosimetry of an X-ray microbeam.

A metal-oxide-semiconductor field effect transistor (MOSFET) has been used as a radiation monitor to map the profile of a variety of X-ray radiation m icrobeams. The present work studies the role of the topology of the MOSFET gate oxide when mapping radiation microbeams. The "edge-on" MOSFET has been introduced for microbeam mapping and the spatial resolution of the "edge-o n" MOSFET is investigated. Comparison is made with other mapping techniques including, Gafchromic(TM) film, radiographic film, ionization chamber. The results clearly demonstrate the superiority of the "edge-on" MOSFET when a pplied to mapping of narrow radiation beams. The spatial resolution of the "edge-on" MOSFET is estimated to be 1 mu m and appears to be limited by the width of the gate oxide thickness.