A NEMA 2012/IEC 2008 phantom was filled with a 177Lu activity concentration sphere-to-background ratio of five.
As the resin spheres and glass spheres are similar in size, the clustering tendency should be the same for 120 Gy regions with glass spheres and 2.4 Gy regions with resin spheres (the same concentration of spheres given a 50-times higher specific activity for glass spheres).
The highest mean RC for any given activity concentration and sphere size was 75.4%, measured on the 37-mm sphere at the highest activity (~ 2.16 MBq/ml).
In contrast, the lowest mean RC for any given activity concentration and sphere size was 14.5%, measured from the 10-mm sphere at the lowest activity level (~ 0.16 MBq/ml).
The trend for reconstructed activities in relation to the activity concentration within spheres was similar for all spheres.
A higher concentration of spheres needed for treatment with lower activity per sphere, i.e., resin spheres, increases the absorbed dose non-uniformity within the liver parenchyma, competing with the increase in non-uniformity due to the higher activity per microsphere of glass spheres.
First, we compute the drag coefficient for periodic arrays of spheres with a variety of concentrations of sphere packings; and second, we prescribe a force density onto a periodic array of spheres, compute the resulting nearby velocity field, and compare these velocities to those computed using an immersed boundary method formulation.
Elongated particles and agglomerates also result in higher viscosity at the same volume concentration as spheres due to structural limitation of rotational and transitional Brownian motion.
A monolayer of HCP microspheres is easy to form under an optimized condition with the temperature, humidity, and the concentration of spheres.
The accuracy of the quantification of the activity concentration in spheres with a diameter of 17 mm and larger for 68Ga-PET with the maximum in VOI method is ± 20%.
