19 October 2022
Radiotherapy treatments in Australia will soon have extra assurance with the arrival of a new national calibration device this month.
Canadian researchers from the National Research Council assembled and trained staff on a new water calorimeter at the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) in Melbourne.
ARPANSA’s Chief Medical Radiation Scientist Ivan Williams said the new Primary Standard is a more accurate calibration device for radiotherapy because human tissue is more similar to water than graphite.
‘Organs like kidneys and the liver are 80% water,’ Dr Williams said.
‘Therefore, we want to measure the absorbed radiation dose to water, uncertainties are reduced if the instrument itself is based on water.
'Radiotherapy centres throughout Australia and New Zealand depend on APRANSA having a primary standard, which is used to calibrate their radiation measurement instruments, or dosemeters. The hospitals use these calibrated dosemeters to ensure that their linear accelerators are delivering the correct radiation dose, thereby ensuring that patients are receiving the correct amount of radiation when they receive treatment.
‘The use of a national primary standard reduces the chance of radiotherapy accidents in Australia, whereby underdosing or overdosing could cause significant harm to patients. Given the new instrument will last for about 30 years, it will underpin the treatment of well over 1 million patients over its operational lifetime.’
The new instrument, valued at $250,000, will be fully tested and modelled prior to running in parallel with the existing graphite primary standard.
When it has been fully tested on ARPANSA linear accelerator beams and checked against the computer models, it will replace the nation’s current graphite primary standard.
ARPANSA have spent a year preparing for the new primary standard and will spend another year in commissioning prior to transitioning to the new standard in 2023.
To commission the new calorimeter, ARPANSA will be compare Australia’s primary standard to those of other countries through The International Bureau of Weights and Measures in Paris to make sure that the calibration device itself agrees with the primary standards of other countries.
