Desarrollo y validación de un procedimiento alternativo para realizar los controles de pureza radioquímica de radiofármacos de 99mTc con un contador Geiger Müller

Background and objectives

In a hospital radiopharmacy with 2a operational level, including the preparation of radiopharmaceuticals from prepared and approved reagent kits, it is common to have a single activimeter or dose calibrator for labeling and fractionation, and to perform the quality controls of the ^99mTc-radiopharmaceuticals. In certain cases, the accumulation of radioactive material or accidental contamination of the work area causes the background to exceed the limits to carry out the radiochemical purity analyses and it is necessary to look for viable alternatives. In this work, a Geiger Müller detector (equipped with a probe for measuring surface contamination) frequently used for radioprotection purposes, was validated as an alternative and its performance was compared against the activimeter for ^99mTc-radiopharmaceuticals.

Materials and methods

Using [^99mTc]pertechnetate, systematic studies of error analyses and detector response to activity concentration, activity and measurement time were carried out in liquid matrices and in paper. The results were compared against an activimeter calibrated for [^99mTc]Tc.

Results

The developed method was used to determine the radiochemical purity of the compounds [^99mTc]Tc-MDP and [^99mTc]Tc-MIBI by ascending paper chromatography tests, obtaining comparable values to those measured with an activimeter in the same system (within 1% uncertainty) and using the method of vial partitioning in a dedicated equipment.

Conclusions

This work demonstrates that a Geiger Müller detector with a probe for measuring surface contamination can be adequately used to replace other equipment in the control of radiochemical purity in the hospital radiopharmacy.