Measuring the Activity of Samples

Measuring the activity of samples involves almost the same technique as weighing samples. However, more setup time must go into preparing the equipment. Before measuring the activity, you must set the detection window on the Single Channel Analyzer (SCA). You must also set the count time on the Dual Counter/Timer. Please consult the manuals for these instruments if you do not know how to adjust these settings.

Once you select the Well Counter function, the programme will display the Full Sample Counting entry screen (above). The screen is laid out as follows:

1. The sample list. This list displays the activity of the samples that have been measured.
2. The measured time. This is the current time measured by the dual counter/timer, and is updated every second during measurement.
3. The measured events. This is the current number of events recorded by the dual counter/timer, and is updated every second during measurement.
4. The sample set letter. This display shows the letter code of the current sample set.
5. The next sample. This display shows the number of the sample that is expected when the NEW SAMPLE button is pressed. Unlike the scale functions, this field is enterable in order to allow the user to specify the next sample number.
6. The NEW SAMPLE button. Click on this button with the mouse pointer when you want to measure the next sample.
7. The STOP button. If you wish to abort a measurement, simply click on this button with the mouse pointer. The counter will be stopped.
8. The DONE button. Click on this button with the mouse pointer when you are finished measuring samples (the data will be saved).
9. The time display. This is the current time, synchronized with CELIA.
10. The date display. This is the current date.
11. The INSERT button. Click on this button with the mouse pointer if you want to insert a sample (you skipped a sample, and need to insert it in the list).
12. The DELETE button. Click on this button with the mouse pointer if you want to delete a sample.
13. The patient name. If patient data is available, the patient name will be displayed here.
14. The run number. The run number of the study being analyzed will be displayed here.

To measure the activity of a sample, place it in the well counter, set the window and count time on the instruments, and enter the sample number in the Next Sample display (if it is not already there). Once everything is set up, click on the New Sample button. You will be prompted to make sure that the sample is in the counter. Once you are sure that everything is set up correctly, click on OK. The counter will start, and the computer will emit a tone.

Once counting has started, you may stop it at any time by clicking on the Stop button. This will abort the current measurement and stop the counter. This may be useful if the dead time is found to be too high during the measurement.

When counting is finished, the computer will emit a tone that is different from the starting tone. The measured number of events will be inserted in the sample list at the proper place.

As samples are measured, the programme will try to guess the next sample number. For example, if samples 10, 9 and 8 have been measured, in that order, the programme will guess that the next sample is 7. Whether the programme expects the sample numbers to be increasing or decreasing is reflected by the Increasing and Decreasing lights on the display. Remember that if you do not wish to measure the sample whose number is displayed in the Next Sample display, you may edit the contents of this display.

Editing, inserting, and deleting samples works in exactly the same way as it does for weighing. Double click on a sample in the sample list if you wish to remeasure it. Click on the Insert button if you wish to insert the sample that is highlighted in the sample list. Click on the Delete button if you wish to delete the sample that is highlighted in the sample list.