Fibre Optic Dosimeter (FOD)

Ref: 11835
A Fibre Optic Dosimeter, for use in the real time monitoring of radiation doses delivered to patients undergoing brachytherapy or other beam radiation treatments.

Key advantages
  • Tissue equivalent radiation dose measurement
  • Real time monitoring of delivered dose
  • Small detection volume
  • No energy, dose rate or temperature dependence


In radiation therapy it is desirable to be able to monitor the actual dose received at the treatment site.

Many current radiation measurement techniques use external monitors, placed in or near the beam, and don’t effectively measure the radiation dose delivered to the tissue.

This inaccuracy may lead to over or under exposure of the patient undergoing radiation therapy. A number of fibre optic dosimeters are available that can be inserted into the patient, through the use of catheters, and the radiation measured at the treatment site.

However current fibre optic dosimeters suffer from the problem of Cerenkov radiation being produced, and travelling down the signal fibre along with the detected signal, thus producing a noisy signal.

The invention

We have shown that Cerenkov light can be reduced to a negligible level in scintillation dosimetry by using an air core light guide to transport the scintillation light signal out of the radiation primary beam.

This novel design has favourable characteristics for megavoltage photon and electron beam dosimetry, with high spatial resolution and fast readout speed, critical for applications such as stereotactic radiosurgery and IMRT.

This technology effectively removes the coincident Cerenkov radiation from the signal pathway – providing an enhanced signal to noise ratio, and providing a much more accurate measurement of the radiation delivered at the target tissue site.

Schematic of Fibre Optic Dosimeter (FOD)

Schematic of Fibre Optic Dosimeter (FOD)


In-situ radiation monitoring for patients undergoing brachytherapy or beam treatments.

Principal inventors

  • David McKenzie
  • Simon Fleming
  • Justin Elsey
  • Susan Law
  • Natalka Suchowerska
  • Jamil Lambert.