2615 - 2612 - Determine age of source; Remark:2608

Calculate the number of days, t, between the source assay date and the current date. The assay date is indicated on the radioactive certification documents or commonly printed on the source label.

There are several online aids available to determine the number of days between two (2) dates. Example: From 15 August 2016 to 14 December 2020, t = 1582 days