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Investigation of a MOSFET dosimetry system for midpoint dose verification in prostate 3D CRT/IMRT


The suitability of MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) for use in in-vivo dosimetry for IMRT prostate treatment and patient setup errors has been investigated in this work. MOSFETs were placed on entrance and exit surfaces of a number of different phantoms (with varying complexities from homogeneous to anthropomorphic). Dose measurements were then used to calculate a midpoint dose, which was compared with an IC placed at the isocentre. The agreements found between the calculated (MOSFETs) and the measured midpoint dose (IC) was: 0.7 % for a prostate treatment verification and 3.5 % for an IMRT treatment. MOSFETs placed on entry and exit surfaces can detect patient setup offsets of 2 cm, but do not have the sensitivity to confidently detect offsets of 1 cm or smaller.

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Correspondence to T. Wiese.

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Wiese, T., Bezak, E. & Nelligan, R. Investigation of a MOSFET dosimetry system for midpoint dose verification in prostate 3D CRT/IMRT. Australas. Phys. Eng. Sci. Med. 31, 180–190 (2008).

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Key words

  • in-vivo dosimetry
  • prostate treatment
  • IMRT