The employee will select a source he is authorized to get from the inventory. The employee will write in the location of use or job order and the route to be taken. The source is selected from inventory as shown in Figure 4 by scrolling through the sources that are in inventory by serial numbers, observing the decay curve and the intensity of the source at that date. He can then select the source he requires; its location is shown. When he strikes, ENTER, the source selected is removed from inventory and the computer is not guarding the detector that is reading the source. The employee can take the source and go to his job location.

What is known at this point:

• The time of day the employee acquired the source.
• The source he has and the intensity.
• The job number he is going on.
• A print-out of all the above transactions plus the shipping papers required to satisfy the code.