Feasibility study of online high-spatial-resolution MOSFET dosimetry in static and pulsed X-ray radiation fields

Improvements have been made in the measurement of dose profiles in several types of X-ray beams. These include 120-kVp X-ray beams from an orthovoltage X-ray machine, 6-MV Bremsstrahlung from a medical LINAC in conformal mode and the 50-200 keV energy spectrum of microbeams produced at the medical beamline station of the European Synchrotron Radiation Facility. Using a quadruple metal-oxide--semiconductor field-effect transistor (MOSFET) sensor chip in 'edge on' mode together with a newly developed sensor readout system, the feasibility of online scanning of the profiles of quasi-static and pulsed radiation beams was demonstrated. Measurements of synchrotron pulsed microbeams showed that a micrometer-scale spatial resolution was achievable. The use of several MOSFETs on the same chip gave rise to the correction of misalignments of the oxide films of the sensor with respect to the microbeam, ensuring that the excellent spatial resolution of the MOSFET used in 'edge-on' mode was fully utilized.