CAPINTEC, INC. CAPTUS
®
600
One Capsule Method
A capsule is measured in a neck phantom. The same capsule is then administered to
the patient. At a later time, the patient returns and the Thyroid (neck) counts and thigh
counts are measured. The uptake is then calculated as:
100
Counts Capsule CorrectedDecay
CountsThigh - CountsNeck
= UptakeThyroid % ×
Standard Capsule Method
This method allows for a calculation of System efficiency with a capsule in a neck
phantom and a Thyroid Uptake calculation based upon the patient dose measured in
a dose calibrator. With this method, only one standard capsule needs to be measured
and stored. Usually this standard capsule is from the same lot of capsules as the
capsules being administered to the patient. To use this method, a standard capsule is
measured at least once daily in a neck phantom and the CAPTUS
®
600 calculates
efficiency in cpm/μCi.
The patient is administered a capsule whose activity is known and entered into the
CAPTUS
®
600 memory.
At a later time, when the patient's thyroid (neck) counts and thigh counts are
measured, the uptake is calculated as:
100
CapsulePatient ofActivity Corrected EFF
CountsThigh - CountsNeck
= UptakeThyroid % ×
×
Two Capsule Method
In this method, one capsule is administered to the patient, while one is stored for later
measurement as a reference capsule.
At a later time when the patient returns for an uptake measurement, the reference
capsule is measured in a neck phantom and the patient neck & thigh are measured.
The uptake is calculated as follows:
100
Counts Capsule Reference
CountsThigh - CountsNeck
= UptakeThyroid % ×
It is important to note that any difference in the original activity of the reference and
administered capsules has a direct effect on the Thyroid Uptake Result.
With this method, there should be as little time as possible between the measurement
of the reference capsule and the patient’s measurement because no decay correction
is made.
2-8 FUNCTIONAL & TECHNICAL DESCRIPTION November 07
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