RESUMEN
Radiopharmaceuticals are a special group of drugs since many of them are eventually prepared in the hospital and the nuclear medicine department is therfore responsible for meeting quality criteria such as sterility, radionuclide, radiochemical and chemical purity. In this study radiochemical purity for more than 300 preparations of three different radiopharmaceutical formulations from commercial kits were tested using instant thin layer chromatography. The formulations namely 99mTc-DTPA, 99mTc-MDP and 99mTc-MIBI were obtained from Pars Isotope Co. Several paper chromatographic systems were used in this study. The result showed that the most observed impurities were hydrolyzed reduced 99m technetium. After the preliminary study we decided to change our imaging schedule in the nuclear medicine department and the sequence of imaging was changed. Cosequently, the results showed better radiochemical purities. Our equipments for detetion of radioactivity in paper chromatography were changed, for example the old dose calibrator was replaced by a gamma camera or a more accurate dose calibrator. Also, the thin layer chromatography systems were changed to those recommended by the factory and the new results showed much better radiochemical purities
RESUMEN
Purpose: Clinical myocardial perfusion SPECT is commonly performed using static imaging. Dynamic SPECT enables extraction of quantitative as well as relative perfusion information. We aimed to evaluate the ability of dynamic SPECT for regular perfusion assessment in comparison to conventional SPECT in the context of thallium-201. Methods: Simulations were performed utilizing a 4D-NCAT phantom for a dual-head gamma camera via the SIMIND Monte-Carlo simulator. 64s acquisition time-frames were used to track these dynamic changes. Different summations of time-frames were performed to create each dataset, which were compared to a standard static dataset. In addition, the effect of different delay-times post-injection was assessed. Twenty-segment analysis of perfusion was performed via the QPS analyser. Dynamic data were subsequently acquired in clinical studiesusing simulation-optimized protocols. Results: For different summations of time-frames, perfusion scores in the basal and mid regions revealed 14.4% and 7.3% increases in dynamic SPECT compared to conventional imaging, with maximum changes in the basal anterior, while the distal and apical segments did not show noticeable changes. Specifically, dynamic imaging including 4 to 6 time-frames yielded enhanced correlation [R=0.957] with conventional imaging, in comparision to the usage of less time frames. Greatest correlation with conventional imaging was obtained for post-injection delays of 320 to 448s [R=0.982 to R=0.988]. Conclusion: While dynamic SPECT opens up an important opportunity for quantitative assessment [e.g. via generation of kinetic parameters], it was shown to generate highly consistent perfusion information compared to established conventional imaging. Future work focuses on merging these two important capabilities