biodex ATOMLAB 500, Operation And Service Manual, Page: 148 / 212

Formulas for Calculating Half Life
d = measurement
d start = starting measurement
d end = ending measurement
Calculate Half Life =
!"# !" ! . !" × ! !"#$
!"# !" ! !"#$" ÷ ! !"#
Example for F-18:
Starting measurement: 4122
Ending measurement: 3860
Counting time: 10 min
Calculate Half Life =
!"# !" ! . !" × !" !"#
!"# !" !"## ÷ !"#$
=
! . !"!# !"#
! . !"#$"!%
= 105.54796 min ÷ 60
Calculate Half Life = 1.759 hr
Variance Formula
Half Life Variance =
!"#!$#"%&' !"#$ !"#$ ! !"#$#%& !"#$ !"#$
!"#$#%& !"#$ !"#$
× 100
Example for F-18:
Half Life Variance =
! . !" ! ! . !"
! . !"
× 100
Half Life Variance = 3.8% lower