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

• Published in: Medical physics (Lancaster) Vol. 27; no. 1; pp. 239 - 244
• Main Authors: Kaplan, Greg I., Rosenfeld, Anatoly B., Allen, Barry J., Booth, Jeremy T., Carolan, Martin G., Holmes-Siedle, Andrew
• Format: Journal Article
• Language: English
• Published: United States American Association of Physicists in Medicine 01-01-2000
• Subjects: Biophysical Phenomena; Biophysics; Collimators; dosimeters; dosimetry; Dosimetry/exposure assessment; Evaluation Studies as Topic; Field effect devices; Gafchromic film; Humans; microbeam; MOSFET; MOSFETs; Phantoms, Imaging; Radiation Monitoring - instrumentation; Radiation Monitoring - methods; Radiation Monitoring - statistics & numerical data; radiation therapy; Radiotherapy Planning, Computer-Assisted; semiconductor counters; Solid‐state detectors; Spatial resolution; Synchrotrons; X-Rays; X‐ray detection; MOSFET; microbeam; Gafchromic film
• ISSN: 0094-2405; 2473-4209
• 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 micrometerdriven miniature collimator attached to a Therapax DXT300 x-ray machine operated at 100
kV
p
.
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.