
Counting statistics 77
Summary: I
n essence, if there is a known number of decays (d
1
) or radioac-
tive nuclei (r
1
) in a sing le voxel and many detectors are used for registering
counts, the distribution of those counts follows the multinomial distribution
with the number of categories of this multinomial distribution equal to the
number of detectors plus one. Depe nding on whether we cons ide r d
1
or r
1
the
K c ategories correspond to detections in K detectors and the additional cat-
egory corresponds to (1) events that are not detected in any detector e lement
or (2) nuclei that do not decay or if they did they are not detected in any
detector element. ...