The use of inorganic exchangers to improve the 82Sr-82Rb generator

Application of 82 Sr/82 Rb generator in neurooncology

INTRODUCTION

The applicability of "Rubidium Chloride, 82 Rb from Generator" radiopharmaceutical for brain tumors (BT) diagnostics is demonstrated on the basis of the application experience of the radiopharmaceutical in neurooncology.

EXPERIMENTAL

A total of 21 patients with various brain tumors and nonneoplastic abnormal brain masses were investigated.

RESULTS AND DISCUSSIONS

The results of the imaging and differential diagnostics of malignant and benign tumors, nonneoplastic abnormal brain masses and lesions revealed the prevalence of high uptake of the radiopharmaceutical in the malignant tumors in comparison with benign glioma and arteriovenous malformations in which 82 Rb-chloride accumulates in the vascular phase but does not linger further. The ultra-short half-life of radionuclide 82 Rb (76 s) along with a low absorbed radiation dose with 82 Rb-chloride by intravenous administration create a new possibility of successive use of two or more radiopharmaceuticals for the examination of the same patient. For instance, PET examination with 18 F-FDG, 11 C-methionine, 11 C-choline, or any other radiopharmaceutical can be carried out in just 7-15 min. after 82 Rb-chloride injection.

CONCLUSION

Research demonstrated an effectiveness of 82 Rb-chloride application as a diagnostic agent in neurooncology. A method of dosing and administration of the generator-produced radiopharmaceutical has been worked out. It is possible to do up to 600 PET sessions using one Russian 82 Rb generator GR-01. The generator is proved to be reliable and easy to use. The interest in 82 Rb-chloride as a tumor-seeking radiopharmaceutical rose due to the active application of the modern devices PET/CT in the routine clinical practice.

Preparation and evaluation of a hydrous tin(IV) oxide 82Sr/82Rb medical generator system for continuous elution

Hydrous tin(IV) dioxide in the Na+-form appears to be the most efficient inorganic exchanger for a reliable and versatile clinical 82Rb generator. Continuous elution with a commercial physiological NaCl solution yields 82Rb ranging between 10 and 40% at a flow rate as low as 3 to 10 mL/min respectively. At the same time the Sr breakthrough is less than 1.6 10(-6)%/mL. A clinical generator loaded with 100 mCi 82Sr (150 mCi 85Sr) and continuously eluted for 3 min at a typical flow rate of 5 mL/min yields 40 mCi of 82Rb, 8 nCi of 82Sr and 11 nCi of 85Sr. The total absorbed radiation dose for 40 mCi 82Rb administered is primarily due to 82Rb and has been estimated for the three principal target organs as 760 mrad for the kidneys, 520 mrad for the heartwalls and 276 mrad for the lungs. The 82,85Sr contribution to the dosimetry has been shown to be negligible. The absence of radiolysis with generators loaded with high level of 82Sr was demonstrated by the excellent reproductibility of continuous elution properties of the generator during its practical shelf-life estimated to 5-6 weeks of clinical use which would require more than 30 L of eluent.