Study of the peak splitting in an alternative method for the radiochemical purity measurement of 99mTechnetium-sestamibi.

One of the alternative methods for the measurement of radiochemical purity (RCP) of Technetium-sestamibi uses Whatman 3MM paper as the stationary phase and ethyl acetate as the mobile phase. However, alternative method shows peak splitting and shouldering of the radiopharmaceutical. This could be because of higher levels of analyte. We aimed to assess the effect of sample dilution (1 : 1) on this method and to compare these RCP values with the reference method. The diluted samples showed a unique peak in the radiopharmaceutical zone, but the RCP values were significantly different (P<0.05) and correlated poorly with the reference method.

Evaluation of alternative rapid thin layer chromatography systems for quality control of technetium-99m radiopharmaceuticals.

Whatman 3MM™ and Tec-Control™ systems were evaluated as ITLC-SG alternatives for 99mTc-radiopharmaceuticals. They compare well in accuracy and reproducibility, and are faster and more convenient than ITLC-SG. Tec-Control™ radiochemical purity values for 99mTc-sestamibi were more conservative than ITLC-SG. Full solvent migration was not reproduced for 99mTc-tetrofosmin in Tec-Control™, and for this Whatman 3MM™ is preferred. Developing times were 10-15 min, 7-9 min and ~1min for ITLC-SG, Whatman 3MM™ and Tec-Control™, respectively. Overall, Tec-Control™ strips are preferred due to speed and ease of use.

Comparison of three cold kit reconstitution techniques for the reduction of hand radiation dose.

In the performance of conventional nuclear pharmacy work, personnel usually receive the highest hand radiation dose during reconstitution of 99Tcm-labelled radiopharmaceuticals. This study was conducted to compare the hand radiation doses incurred during the preparation of 99Tcm-labelled radiopharmaceuticals using three different reconstitution procedures: (1) the standard reconstitution method (i.e. withdrawing 99Tcm activity and normal saline [NS] into the same syringe before adding to the cold kit) (standard); (2) an alternative reconstitution procedure using two syringes to add normal saline separately before 99Tcm activity to the cold kit (NS/Tc); and (3) a standard reconstitution procedure using a robotic system (Amercare Syringe Fill Station, model NuMed SFS 3a, Amercare Ltd, Oxon, UK) (robot). Radiation doses were monitored by thermoluminescent dosimeters (Landauer Inc., Glenwood, IL, USA) on the base of the fourth finger (i.e. ring finger) of the non-dominant hand and on the mid-portion of the second finger (i.e. index finger) of the dominant hand. Three sets of ring badges were measured for each procedure, with 10 stimulated or real reconstitutions per set. Two different radiopharmaceutical kits were evaluated: 99Tcm-MDP, as it is the most frequently used radiopharmaceutical in the majority of nuclear medicine departments (all three reconstitution methods; i.e. standard, NS/Tc and robot), and 99Tcm-sestamibi, as it is not only reconstituted with the highest amount of radioactivity but is also the most frequently dispensed radiopharmaceutical in our laboratory (standard and robot). All kits were prepared from an elution vial containing a standardized amount of 99Tcm activity (i.e. 104.4 +/- 3.6 GBq). To each of the cold MDP and sestamibi kits, 20.7 +/- 1.2 GBq and 44.2 +/- 0.7 GBq of 99Tcm activity were added, respectively. Average accumulated radiation doses for 10 reconstitutions to the fingers (non-dominant/dominant) for the preparations of 99Tcm-MDP were as follows: 14.2 +/- 0.9 mSv/2.8 +/- 0.8 mSv (standard), 10.0 +/- 0.6 mSv/2.7 +/- 0.2 mSv (NS/Tc), and 0.6 +/- 0.1 mSv/1.3 +/- 0.1 mSv (robot). For 99Tcm-sestamibi, the average accumulated radiation doses for 10 reconstitutions to the fingers (non-dominant/dominant) were 6.7 +/- 0.7 mSv/4.6 +/- 0.5 mSv (standard) and 1.1 +/- 0.1 mSv/3.1 +/- 0.4 mSv (robot). When compared to the standard reconstitution method, our results show that the NS/Tc method slightly reduced radiation dose to the non-dominant hand, without any significant reduction for the dominant hand. However, the robot has proved to be the most effective method to considerably reduce radiation dose to both hands. A robotic system should be a useful ALARA (as low as reasonably achievable) tool to prepare other high-activity 99Tcm-labelled radiopharmaceuticals, as well as therapeutic and PET radiopharmaceuticals.

The influence of generator eluate on the radiochemical purity of 99Tcm-sestamibi prepared using fractionated Cardiolite kits.

The reconstitution of fractionated Cardiolite kits with sodium 99Tcm-pertechnetate eluted from a wet-column 99Mo/99Tcm generator results in a preparation that contains elevated amounts of a polar radiochemical impurity, which is normally present in only trace amounts when such kits are reconstituted with eluate from a dry-column generator. A consequence of this impurity, which appears to be an organotechnetium compound, is that it causes a positive bias in several quality control methods for 99Tcm-sestamibi, including that recommended by the manufacturer. This impurity was isolated, and its biodistribution determined in Wistar rats. Two alternative methods for the preparation of 99Tcm-sestamibi from fractionated Cardiolite kits using eluate from a wet-column generator were investigated. A rapid procedure, based on a C18 solid phase extraction (SPE) cartridge, for measuring the radiochemical purity of 99Tcm-sestamibi samples, which had been prepared using fractionated Cardiolite kits, was developed and compared with two other methods including high-performance liquid chromatography (HPLC). Over a radiochemical purity range of 49-98%, the values obtained using our quality control method deviated from those obtained using HPLC by 1.1 +/- 1.3% (n = 26). In contrast to some of the rapid quality control methods assessed in our investigation, the SPE technique was not biased by the presence of the organotechnetium impurity.