Improved spatial resolution by MOSFET dosimetry of an x-ray microbeam

Med Phys. 2000 Jan;27(1):239-44. doi: 10.1118/1.598866.


Measurement of the lateral profile of the dose distribution across a narrow x-ray microbeam requires a dosimeter with a micron resolution. We investigated the use of a MOSFET dosimeter in an "edge-on" orientation with the gate insulating oxide layer parallel to the direction of the beam. We compared results using this technique to Gafchromic film measurements of a 200 micrometer wide planar x-ray microbeam. The microbeam was obtained by using a vernier micrometer-driven miniature collimator attached to a Therapax DXT300 x-ray machine operated at 100 kVp. The "edge-on" application allows utilization of the ultra thin sensitive volume of the MOSFET detector. Spatial resolution of both the MOSFET and Gafchromic film dosimeters appeared to be of about 1 micrometer. The MOSFET dosimeter appeared to provide more uniform dose profiles with the advantage of on-line measurements.

Publication types

  • Comparative Study

MeSH terms

  • Biophysical Phenomena
  • Biophysics
  • Evaluation Studies as Topic
  • Humans
  • Phantoms, Imaging
  • Radiation Monitoring / instrumentation*
  • Radiation Monitoring / methods
  • Radiation Monitoring / statistics & numerical data
  • Radiotherapy Planning, Computer-Assisted
  • Synchrotrons
  • X-Rays