However, while the three nonradioactive NTPs are normally used at mM ranges, the concentration of the radioactive NTP (i.e. α-32P-GTP) is relatively very low (0.08 to 50 µM), simply because the highly concentrated radioactive NTP is not readily available, and use of a large quantity of radioactivity is technically challenging.
First, the scientists felt that the acute onset of gastro-intestinal symptoms in Arafat, who first fell ill four hours after eating dinner in October 2004, as well as the progressive deterioration of his state in the following weeks were "compatible with ingestion of a large quantity of radioactivity".
The quantity of radioactivity was expressed as the percentage of injected dose per gram of tissue (% ID/g).
Whether the necessary quantity of radioactivity would allow for PET imaging remains to be determined in patients.
A level seven rating is defined as "An event resulting in an environmental release corresponding to a quantity of radioactivity radiologically equivalent to a release to the atmosphere of more than several tens of thousands of TBq of Iodine-131".
Although the amount of peptide conjugate was kept constant for the labeling, i.e. 5 μg, the quantity of radioactivity varied in each case, explaining the observed variations in specific activity.
Based on the results obtained from this proof-of-concept study, 47Sc has the potential to be produced in a suitable quality for clinical applications, however, the quantity of radioactivity still needs to be expanded to meet the requirements for radionuclide therapy.
The commercial 68Ge/68Ga generator system ensures an easy and flexible availability of 68Ga, however, only a limited quantity of radioactivity (equivalent to two patient doses when using a new generator) can be obtained per elution (Eppard et al. 2013, Rösch 2013).
These data are in agreement with studies performed with primary B cells labeled with [H]arachidonic acid (15), both in the profile of DAG accumulation and the quantity of radioactivity.
