Adsorption of 99mTc-Radiopharmaceuticals onto Injection Vials and Syringes

Abstract

Many groups have reported the adsorption or retention of 99m Tcradiopharmaceuticals on injection vials and disposable plastic syringes. Such an enormously high loss of radioactivity would result in poor images, radiation exposure, waste, and economic burdens. We therefore decided to investigate the extent of adsorption or retention of several 99m Tc-radiopharmaceuticals on injection vials, rubber stoppers, and plastic syringes. These radiopharmaceuticals are produced as lyophilized kits in our department and supplied to various hospitals practicing nuclear medicine in Pakistan. Methods: A vial containing lyophilized material was reconstituted with 3 mL of freshly eluted Na 99m TcO 4 . A 1-mL aliquot of the resulting solution was withdrawn into a syringe at 0.25, 0.5, 1, 3, and 5 h after preparation. All preparations were stored at room temperature (;22°C). After each withdrawal, the vial was reweighed and the activity remaining in the vial was measured using a radioisotope calibrator. The sample was reinjected into the vial. From the original weight and activity of solution in the vial, the initial activity per gram was calculated. From the weight and activity remaining in the vial after withdrawal of the sample, the activity per gram of the sample was calculated. From the difference between the initial activity per gram and the activity per gram of the sample, the percentage of 99m Tc adsorbed on the vial was calculated. All preparations were kept in the syringe for 15 min, and the activity was measured before and after the syringe was emptied. The needle and plunger of the syringe were separated, and activity in the needle and plunger was also measured. Results: The labeling efficiency of all radiopharmaceuticals used during these studies was more than 95%. In most cases, the activity of 99m Tc found on the rubber stopper was less than 1%. Adsorption of 99m Tc onto vials increased gradually with storage time. Adsorption was minimal at the initial stages, whereas maximum retention was noted after 5 h. Nearly 5% adsorption of activity was observed after 5 h of storage time on vials of sestamibi, mercaptoacetyltriglycine, dextran, ciprofloxacin, and dimercaptosuccinic acid (III and V). Retention of activity on needles ranged from 1% to 2% for all preparations studied. Plungers did not show any significant retention of radioactivity; in most cases, retention was less than 0.5%. The maximum retention of radioactivity on plastic syringe bodies was more than 3% for sestamibi, dimercaptosuccinic acid, dextran, pyrophosphate, and phytate. Conclusion: The results revealed that losses of radioactivity from 99m Tc-radiopharmaceuticals in these objects (glass vial, rubber stopper, plastic syringes, plungers, and needles) are not alarming in our setup.

Systematic Assessment of the Adsorption of 99mTc-Radiopharmaceuticals onto Plastic Syringes

“…Radioactive retention of less than 3% is in the range of our gravimetrically determined dead volume. That excludes an adsorption of these radiopharmaceuticals in the syringe and confirms published data (8). The undiluted preparation of 99m Tc-butedronate showed a slightly higher retention rate of 3.6% in brand A, but this was considered insignificant (P .…”

“…The phenomenon of adsorption of 99m Tc-radiopharmaceuticals onto plastic syringes has been previously examined (2)(3)(4)(5)(6)(7)(8). Therefore, we established a procedure for the assessment of adsorption onto syringes under standardized conditions and tested a variety of 99m Tc-radiopharmaceuticals.…”

“…In this study, we aimed to contrive a standard method for adsorption assessment to compare different plastic syringes with various radiopharmaceuticals under identical experimental conditions. We tested 99m Tc-radiopharmaceuticals such as 99m Tcpertechnetate or 99m Tc-diphosphonates, which are described as inconspicuous about adsorptions (8), and proved our concept with known adsorbing 99m Tc-radiopharmaceuticals, such as 99m Tcsestamibi, 99m Tc-tetrofosmin, and 99m Tc-succimer. Furthermore, we gravimetrically determined the dead space to obtain a correlation between the actual adsorption and the residual volume remaining in the disposable syringe.…”

Retention of 99mTc-DMSA(III) and 99mTc-nanocolloid in different syringes affects imaging quality

“…Several authors report that, in their hands, the adsorption of a substantial number of tracers to the syringe was below 3-4%, which was seemingly not affected by the syringe brand [3,4]. Several authors report that, in their hands, the adsorption of a substantial number of tracers to the syringe was below 3-4%, which was seemingly not affected by the syringe brand [3,4].…”

The clinical importance of accurate measurement of injected doses for radionuclide myocardial perfusion imaging

“…However, this method of calculation does not take into consideration the potential adherence of the radiotracer to the various parts of the injection system (including syringe, tubing, and 3-way stopcock). Although most of the 99mTc-labeled radiopharmaceuticals used in nuclear medicine 5 are not considered to be problematic with regard to adherence or adsorption to the syringe or tubing (except for 99mTc-macroaggregates of albumin used for lung scanning and detection of pulmonary embolism, 99mTc-sulfur colloid for liver scanning and 99mTc-dimercaptosuccinic acid for renal imaging), [6][7][8] enhanced retention of lipophilic radiopharmaceuticals such as 99mTc-sestamibi and 99mTc-tetrofosmin has been reported in syringes made with elastomeric plunger tips. [9][10][11] High residual radioactivity in the syringes and tubing can lead to the delivery of a suboptimal dose to the patient resulting in poor image quality, sometimes extending the image acquisition time or, worse, forcing to repeat the study with another separate injection, unnecessarily increasing the radiation dosimetry to the patient.…”