Comparing the measured affinity of ¹¹¹In-labeled ligands for cellular receptors by monitoring gamma, beta, or X-ray radiation with three different LigandTracer^® devices

LigandTracer instruments measuring high energy photons (gamma-rays), particles (electrons and positrons) and low energy photons (X-rays) are novel semi-automated devices which produce real-time radiotracer-receptor interaction data for measurement of the affinity. The affinities of two different ¹¹¹In-labeled ligands were measured in three different LigandTracer devices detecting high energy gamma, Auger and internal conversion electrons, or X-rays. The obtained similar uptake/retention patterns (binding curves) show that even at low signal-to-noise ratios (data from Auger and internal conversion electrons, and X-rays), reliable binding data can be captured. This verifies that different devices could be used as alternatives for kinetic evaluation studies for radionuclides emitting different type of radiation.