ARPANSA provides calibration services for radiotherapy dosimeters. These dosimeters are used by radiotherapy providers to calibrate the output of linear accelerators and kilovoltage X-ray tubes for patient treatment.

Calibration services

The current scope of services can be viewed at www.nata.com.au.

To inquire about the calibration of ionisation chambers for radiotherapy providers, contact psdl@arpansa.gov.au.

Future events

2025 Practical Reference Dosimetry Course will run from 31 March to 3 April 2025. Register for ARPANSA's Practical Reference Dosimetry Course 2025 here.

Calibration standard

Most of these services are accredited to ISO/IEC17025 by NATA. ARPANSA’s accreditation number is 14442.

Calibration types

There are several beam qualities available for calibration. The most common calibration is for absorbed dose to water in Cobalt-60. This calibration may be used with a dosimetry protocol such as the IAEA TRS-398 Code of Practice to determine the output of a medical linear accelerator. Radiotherapy providers can choose to get their ionisation chambers calibrated at ARPANSA directly in linear accelerator beams. The services result in more accurate dosimetry in the clinic because the chamber is calibrated at similar energies, reducing the emphasis on correction factors.

The services are fully compatible with the IAEA’s TRS-398 dosimetry code of practice and are intended to complement the existing Cobalt-60 calibration service.

Table 1: Common calibration combinations of a therapy dosimeter (consisting of an electrometer and one or more ionisation chambers).

DeviceBeam qualityNominal energyQuantityCalibration coefficient
Electrometera--Charge or currentkelec
Thimble chamberCobalt-60Cobalt-60Absorbed dose to waterbND,w
Thimble chamberCobalt-60Cobalt-60Air kermaNK
Thimble chamberCobalt-60 + MV photons1 – 18 MVAbsorbed dose to waterND,w,Q
Electron chamberMV electrons18 MeVcAbsorbed dose to waterND,w,Q
Thimble chamberMEXd30 – 300 kVpAir kermaNK
Thin window chamberLEXe20 – 100 kVpAir kermaNK

aElectrometers are calibrated separately from ionisation chambers. A comparison of the product of the separate calibration coefficients and the combined calibration coefficient is however performed in Cobalt-60.
bCalibrations in Cobalt-60 include a calibration for air kerma, which is always performed for QA purposes.
cThe cross-calibration is performed at 18 MeV and calculated correction factors from TRS-398 can be used to determine the calibration coefficient at other qualities.
dMEX = Medium Energy kilovoltage X-rays
eLEX = Low Energy kilovoltage X-rays

A current list of the dosimetry capabilities of ARPANSA's PSDL and Medical Imaging:

Radiotherapy 

Radiological qualityBeam qualityEnergies
Absorbed dose to water60Co 
MV linac photons6, 10 and 18 MV
MV linac electronsCross-calibration at 15 MeV
Air kerma60Co 
Medium Energy X-rays40-320 kVp ‘NX’ series
Low Energy X-rays20-100 kVp ‘RT’ series

Diagnostic

Radiological qualityBeam qualityEnergies
Air kerma
(KAP, KLP in development)
General radiographyRQR, RQA, RQT series

Protection

Radiological qualityBeam qualityEnergies
Air kerma and dose equivalent*60Co, 137Cs, Medium energy X-raysAbove X-ray series plus ISO 4037 Narrow and Wide series
Dose equivalent*Am/Be neutrons 

*Includes ambient dose equivalent H*(10) (calibrated free in air) and personal dose equivalent Hp(10) (calibrated on a phantom).

Past events

For more information contact: psdl@arpansa.gov.au

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