Production and biomedical use of non-conventional positron emitters
Abstract: Positron Emission Tomography (PET) is a powerful diagnostic tool. So far, it has mainly been associated with the use of short-lived positron emitters with half-lives shorter than 2 h, like 11C and 18F. However, many biochemical processes in vivo have to be monitored for several hours or longer and thus positron emitters with longer half-lives are of interest. Sometimes, the replacement of single-photon emitting nuclides by positron emitting counterparts in established radiopharmaceuticals enable to use PET, which has better resolution and enables easier quantification.A new production method for the halogen 76Br (T1/2 = 16 h) is presented in paper I. An efficient dry distillation method is used for separation of this isotope from an isotopically enriched copper selenide target. This production method provides a nuclide with high chemial quality, which enabled simple labeling of monoclonal antibodies using Chloramine-T in mild neutral conditions. This nuclide was successfully used in a PET pharmacokinetic study on the effect of dextranation of peptides.A new method (etching technique) was developed to produce a positron-emitting isotope of indium, 110In (T1/2 = 69 min) and gallium, 68Ga (T1/2 = 68 min) and 66Ga (T1/2 = 9.4 h). A somatostatin analog, DTPA-octreotide, was labelled with 110In and used in a PET study. The use of PET enabled at efficient visualization of tumor metastases as well as dosimetric calculations.Dry distillation technique was used to produce zinc isotopes, which are of interest for investigation of trace element metabolism in vivo. At the same time, dyy distillation of group IIB elements from target material belonging to group IB of Periodic Table was examined. It has been shown that diffusion in solid state is the rate-determining process in such separations.
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