Standardisation of super(90)Y and determination of calibration factors for super(90)Y microspheres (resin) for the NPL secondary ionisation chamber and a Capintec CRC-25R

The use of super(90)Y resin microspheres (SIR-Spheres registered microspheres) in Nuclear Medicine has dramatically increased in recent years due to its favourable outcome in the treatment of liver cancer and liver metastases (Rajekar et al., 2011). The measurement of administered activity before and residual activity after treatment in radionuclide calibrators is required to determine total activity delivered to the patient. In comparison with External Beam Radiotherapy (EBRT) where administered doses are often know to within plus or minus 5%, the actual administered activity in nuclear medicine procedures may only be known to within plus or minus 20% and subsequent dose calculations can result in even larger uncertainties (Fenwick et al., 2009). It is a well-recognised issue that ion chambers are instruments that are sensitive to the measurement geometry and matrix of a source, in particular for pure beta or low energy (