90Y is a therapeutic radiopharmaceuticals used in the treatment of liver cancer following implantation via a catheter in the hepatic artery, 90Y microspheres are embolised in the microvasculature of liver cancer where they irradiate the tumour by a process known as selective internal radiation therapy. SIR-spheres are radiopharmaceutical products that are comprised of 90Y microspheres suspended in sterile, pyrogen-free water for injection into patients. It is necessary to establish for the SIR-spheres production the capability of accurately measuring the activity of this product to a traceable national measurement standard. In the SIR-spheres product, the microspheres are non-biodegradable plastic beads, which have a density of 1.0 g/ml and a diameter of approximately 35 mm. 90Y used was the nuclear reactor-produced radionuclide. The concentration of the microspheres is approximately 40% and patient doses of SIR- product are usually prepared in a Wheaton vial by ARI with an activity of 3 GBq in a volume of 5 ml. The direct standard transfer is limited to a small quantity of SIR-spheres of about 1ml due to the difficulty of effectively digesting a large quantity of SIR-spheres such as 5 ml. The calibration factor for 5ml SIR-spheres may be derived from the factor for 1ml SIR-spheres, although relatively large uncertainty may be introduced due to the inhomogeneity of activity concentration dispensed into 1 and 5ml samples.
Reference:
Mo, L, et al. 2005. Development of activity standard for 90Y microspheres. Applied Radiation and Isotopes, vol 63(2), pp 193-199
Mo, L., Avci, B., James, D., Simpson, B., Van Wyngaardt, W., Cessna, J., & Baldock, C. (2005). Development of activity standard for 90Y microspheres. http://hdl.handle.net/10204/1572
Mo, L, B Avci, D James, B Simpson, WM Van Wyngaardt, JT Cessna, and C Baldock "Development of activity standard for 90Y microspheres." (2005) http://hdl.handle.net/10204/1572
Mo L, Avci B, James D, Simpson B, Van Wyngaardt W, Cessna J, et al. Development of activity standard for 90Y microspheres. 2005; http://hdl.handle.net/10204/1572.