Modeling the time dependent distribution of a new (153)Sm complex for targeted radiotherapy purpose

For radioimmunotherapy purposes, a chemical complex with high absorption in cancer tumor is required. New chemicals are to be examined for their concentration in tumor and healthy organs. These are labeled with β-emitting radioisotopes to irradiate the tumor while deposited inside it.

To study the capability of recently developed chemical complex in targeting cancer tumor and investigate the distribution of (153)Sm-TPTTC in rat organs as function of time.

The chemical complex - [Tris(1,10-phenanthroline)Samarium(III)] trithiocyanate was prepared and labeled with (153)Sm radioisotope. The labeled complex was injected to a population of tumor bearing mice. In 2, 4, 24, 48, 96 h after injection the animals were sacrificed and the concentration of Samarium complex was measured in various organs such as blood, heart, intestine, colon, liver, spleen, kidney, sternum and bone.

The concentration of the radiopharmaceutical in various organs was measured at different times. The temporal behavior of biodistribution of (153)Sm-TPTTC was modeled and drawn as function of time.

It is shown that (153)Sm-TPTTC is concentrated in tumor tissue and liver much more than in other organs. The variation of pharmaceutical concentration in all organs is described with summation of eight exponential terms and it approximates our experimental data with precision better than 2%.