Particle size analysis: 90Y and 99mTc-labelled colloids

Area of Science:

• Nuclear Medicine
• Radiopharmaceutical Science
• Materials Science

Background:

• Colloidal particle size is a critical factor in selecting radiopharmaceuticals for diagnostic and therapeutic applications.
• Accurate particle-size determination is essential for predicting the behavior and efficacy of radiocolloids.

Purpose of the Study:

• To determine the particle-size distribution of (90)Y- and (99m)Tc-labeled antimony trisulfide (Sb(2)S(3)) and tin colloids (Sn-colloid).
• To compare the effectiveness of Photon Correlation Spectroscopy (PCS) and Transmission Electron Microscopy (TEM) in radiocolloid particle-sizing.

Main Methods:

• Utilized Photon Correlation Spectroscopy (PCS) to measure particle-size distribution.
• Employed Transmission Electron Microscopy (TEM) for high-resolution particle-size analysis.
• Analyzed (90)Y-Sb(2)S(3), (99m)Tc-Sb(2)S(3), (90)Y-Sn colloid, and (99m)Tc-Sn colloid.

Main Results:

• PCS measurements for (90)Y-Sb(2)S(3) and (99m)Tc-Sb(2)S(3) yielded diameters of 28.92 ± 0.14 nm and 35.61 ± 0.11 nm, respectively.
• TEM measurements for (90)Y-Sb(2)S(3) showed a mean diameter of 14.33 ± 0.09 nm.
• PCS revealed bimodal size distributions for (90)Y-Sn colloid (d(v(max1)) = 805 nm, d(v(max2)) = 2590 nm) and a predominant size of ~910 nm for (99m)Tc-Sn colloid.
• Significant discrepancies were observed between TEM and PCS mean diameter measurements for (90)Y-labeled Sb(2)S(3) and Sn colloid.

Conclusions:

• Transmission Electron Microscopy (TEM) offers superior resolution and reliability for radiocolloid particle-sizing compared to Photon Correlation Spectroscopy (PCS).
• TEM is the preferred method for accurate size characterization of radiocolloids used in nuclear medicine.