Graphics Reference
In-Depth Information
Figure
.
.
he scanning, acquisition and reconstruction process of a PET system
image, one can subtract the number of photon pairs resulting from the presence of
AC events (Politte and Snyder,
; Fessler,
).
Suppose the target image is partitioned into B boxes (or pixels in
-D or voxels
in
-D), and there are D detector tubes formed from pairs of detectors positioned
outside the body. For each pixel, b
=
,
,...,B,andeachtube,d
=
,
,...,D,the
following notations are adopted:
λ
(
b
)
: the emission intensity of the target at box b
q
(
b, d
)
: the probability of an emission from box b being detected along detector
tube d
s
: the survival probability that a photon pair emitted from box b and trav-
eling in tube d will have an energy that is greater than the threshold level of the
detectors ater attenuation.
(
b, d
)
With attenuation, the transition probability becomes
p
(
b, d
)=
q
(
b, d
)
s
(
b, d
)
(
.
)
