Audit on source strength determination for HDR and PDR (192)Ir brachytherapy in Sweden.
OBJECTIVE
To investigate the status of source strength determination in terms of reference air kerma rate (RAKR) for HDR and PDR (192)Ir brachytherapy in Sweden.


METHODS
RAKR was determined in each of the 14 Swedish afterloaders, using calibrated equipment from the Swedish Secondary Standard Dosimetry Laboratory.


RESULTS
Values of RAKR from the external audit, the hospitals and vendors agreed within the uncertainty limits guaranteed by the vendors.


CONCLUSIONS
The accuracy in RAKR determination has increased over the last years as a result of increased availability of interpolation standards for HDR (192)Ir and the increased use of robust well-type ion chambers designed for brachytherapy. It is recommended to establish a ratio between the RAKR value from own measurements at the hospital and that of the vendor since such a ratio embeds constant systematic differences due to e.g. varying traceability and therefore has the potential of being less uncertain than the RAKR alone. Traceability to primary standards for HDR (192)Ir sources will in the future significantly decrease the uncertainty in RAKR of (192)Ir brachytherapy.
Carlsson Tedgren
Asa
A
Department of Medical and Health Sciences, Linköping University, Linköping, Sweden. asa.carlsson-tedgren@imv.liu.se
Grindborg
Jan-Erik
JE
D001918:Brachytherapy; D007496:Iridium Radioisotopes / Q000627:therapeutic use*; D011874:Radiometry; D011879:Radiotherapy Dosage
D007496:Iridium Radioisotopes