Capintec CRC-25R - ABBREVIATIONS USED IN TABLE I; UNCERTAINTY DUE TO SYRINGE CORRECTION; UNCERTAINTY DUE TO PUBLISHED DATA

CAPINTEC, INC CRC
®
-25R
ABBREVIATIONS USED IN TABLE I
Abbreviation Meaning Abbreviation Meaning
eqb. equilibrium D days
S seconds Y years
H hours E exponential, i.e.,
M minutes
3E5 = 3 × 10
5
UNCERTAINTY DUE TO SYRINGE CORRECTION
The Calibration Setting Numbers are given for approximately 5 grams of radioactive solution
in a standard source ampoule made of about 0.6mm thick borosilicate glass. The standard
radioactive source in the ampoule is, however, a good approximation for a
radiopharmaceutical in a plastic syringe or a glass syringe (wall thickness about 1.2mm) for
most radioisotopes.
In general, the attenuation of radiation by a plastic syringe is less than for the standard
ampoule, while for most glass syringes, the attenuation will be greater than for the standard
ampoule.
The anticipated syringe corrections are listed on the table under the column "Uncertainty Due
to Syringe Correction". For example, the required correction for I125 activity is estimated to
be about, ±25%. This means that you should add 25% to the meter reading if the I125 is in a
glass syringe or subtract 25% if it is in a plastic syringe.
Since the attenuation of low energy radiation is very dependent upon the material of the
container, the value given in the syringe correction column should be used mainly as a guide
giving relative magnitude.
If a measurement of activity in a glass vial is anticipated, the container correction for low
energy isotopes will be substantial. It could be about 3 to 5 times that for a syringe.
If no value is given in this column, the correction is not significant, except for a container
differing greatly from the standard ampoule (e.g. very thick glass container, vial made of
glass which contains lead, etc.).
UNCERTAINTY DUE TO PUBLISHED DATA
This is the uncertainty on the value of the activity. From calibration numbers calculated from
decay data, the uncertainty given is calculated using only the reported errors on the intensity
of the γ and/or x-rays. For calibration numbers measured from NBS standard reference
materials (known as SRM;s), the uncertainty given is the reported uncertainty on the activity
of the SRM. For these numbers, the reference is given as NBS (or LMR - Laboratoire de
Metrologie de la Radioactivite - France), and year of source.
June 09 APPENDIX II A2 - 5