Experimental determination of dose calibrator settings and study of associated volume dependence in v-vials for rhenium-186 perrhenate solution sources.
OBJECTIVE
Accurate activity measurements of glass conical v-vials are only possible if dose calibrator dial settings are experimentally determined for the specific vial and volume range over which the measurements of a particular radionuclide is to be made. V-vials are used to transport and store unit doses of radiopharmaceuticals containing high-energy beta-emitters, such as 186Re. We have determined the correct dose calibrator dial settings for measuring 186Re in 3-mL glass conical v-vials from 2 manufacturers.


METHODS
The 186Re solutions used were calibrated for radioactivity content at the National Institute of Standards and Technology (NIST) using liquid scintillation counting with 3H-standard efficiency with a maximum expanded (k = 2) uncertainty of 1.2% on the activity. Volumes of the solutions then were accurately dispensed into a set of v-vials from each of the 2 manufacturers and assayed in the dose calibrator maintained at NIST.


RESULTS
For filling volumes above 1 mL, the dose calibrator response was found to be constant for both of the vials studied, enabling a single dial setting to be used for each vial type. The expanded uncertainties on the activity from uncertainty in the dial setting in that volume range were 0.4%-0.7%. Variability in vial construction contributed another 0.2%-0.3% in the uncertainty in the activity determination.


CONCLUSIONS
These studies indicate a strong volume dependence on the response of the dose calibrator and highlight the need for experimental verification of dose calibrator settings for nonstandard geometries.
Zimmerman
B E
BE
Physics Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA. bez@nist.gov
Pipes
D W
DW
D002138:Calibration; D011868:Radioisotopes / Q000008:administration & dosage* / Q000592:standards; D019275:Radiopharmaceuticals / Q000008:administration & dosage* / Q000592:standards; D012211:Rhenium / Q000008:administration & dosage* / Q000592:standards; D012996:Solutions; D013679:Technology, Radiologic / Q000295:instrumentation*
D011868:Radioisotopes; D019275:Radiopharmaceuticals; D012996:Solutions; C015428:perrhenate; D012211:Rhenium