Monte Carlo Based Dose Assessment for 90Y Radioembolization, A Comparison between 99mtc-MAA SPECT/CT and 90Y-Microspheres PET


Sjoerd Rijnsdorp, Daniela OpreaLager, Jan de Vries, Arthur van Lingen

The aim of this research was to assess the agreement between the distribution of technetium-99m macroaggregated albumin (MAA) and yttrium-90 microspheres in radioembolization of the liver, as well as the correspondence between the desired radiation dose and the true radiation dose in the target area.

Materials and Methods: The relative distribution of yttrium-90 microspheres was estimated in 5 patients, using the activity distributions from technetium-99m MAA SPECT/CT and yttrium-90 PET/CT imaging. A Monte Carlo simulation using these relative activity distributions was used to calculate the radiation dose to the liver.

Resultsand Discussion: A large difference in radiation dose was found when comparing technetium-99m MAA and yttrium-90 microspheres distributions. In addition, the distribution of yttrium-90microspheres in the liver, obtained from the PET images, was highly inhomogeneous.Relative technetium-99m MAA distribution does not necessarily comply with the distribution of yttrium-90 microspheres. Therefore, technetium-99m MAA scans cannot directly be used for prospective radiation dose assessment. Due to the inhomogeneity of the distribution of yttrium-90 microspheres, the estimated radiation dose in large parts of the targeted lobe(s) is smaller than the desired radiation dose.


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