biodex ATOMLAB 500, Руководство по эксплуатации и обслуживанию, Страница: 111 / 212

Example: If using Tc-99m for
linearity: Starting Activity:
250 mCi
Half Life:6 hours
Time required for activity to decay below 10 µCi is 96 hours
NOTES:
•
Taking measurements every 6 hours will require 16 readings to decay below 10 µCi.
•
Taking measurements every 2 hours would require 48 readings to decay
below 10 µCi.
• A linearity test with Tc-99m is normally measured at 6 hour intervals.
•
Make sure the parameters are set up with enough readings to complete the
linearity test in 60 readings.
Lineator Initial Test
Figure 6.63. The Lineator Initial Test Screen.
The first time the Lineator is used with this dose calibrator, initial factors for the Lineator
function must be set and the Atomlab 500 must be calibrated for the specific Lineator
package using the initial procedure described below. The Atomlab 500 will store the initial
factors and print them in the initial factor column of the results table.
The initial Lineator Test needs to be performed only once unless the Lineator is replaced or
damaged, in which case the initial factors will need to be redone. The Atomlab 500
procedure allows recording of two initial linearity tests; one less than 55
m Ci and one
greater than 55 m Ci. The Lineator does not have a wide enough range using the tube
combinations to obtain a minimum reading of less than 10 µCi when starting with an
activity greater than 55
m Ci. Using two linearity ranges allows the user to obtain a
maximum reading in excess of 500 m Ci to less than 10 µCi.
NOTE: The initial test and future tests should all start with similar starting activities.
Variation in starting activities can cause variance in results.
NOTE: Some state regulations allow linearity tests to end at activities greater than 10 µCi.
The user can discontinue the linearity test at the activity permitted by state regulations or
license.