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 microbeams. 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-on' MOSFET is investigated. Comparison is made with other mapping techniques including, [Gafchromic.sup.TM] film, radiographic film, ionization chamber. The results clearly demonstrate the superiority of the 'edge-on' MOSFET when applied to mapping of narrow radiation beams. The spatial resolution of the 'edge-on' MOSFET is estimated to be 1 [micro]m and appears to be limited by the width of the gate oxide thickness,