Adaptive Autoregressive Model for Reduction of Noise in SPECT

Table 4

Full width at half maximum values for the different methods.

Method	RelAct	10 Ø	20 Ø	40 Ø	60 Ø
A
AR-OSEM-AR	0	19.7	25.0	45.8	64.8
BW-FBP	0	17.9	23.2	43.5	63.8
OSEM-BW	0	19.4	23.2	43.6	62.8
AR-OSEM-AR	2	—	21.5	35.3	59.1
BW-FBP	2	—	23.2	36.6	59.6
OSEM-BW	2	—	22.2	35.8	59.1
AR-OSEM-AR	4	13.4	18.4	37.8	57.8
BW-FBP	4	15.8	20.4	37.9	57.9
OSEM-BW	4	15.2	19.9	37.7	57.9
B
AR-OSEM-AR	0	23.7	23.7	43.0	62.3
BW-FBP	0	18.6	22.4	41.2	61.4
OSEM-BW	0	18.8	23.2	41.9	61.7
AR-OSEM-AR	2	19.4	19.8	38.9	59.0
BW-FBP	2	19.0	21.0	38.5	58.9
OSEM-BW	2	17.7	19.9	38.5	59.0
AR-OSEM-AR	4	13.0	19.7	37.8	58.2
BW-FBP	4	15.4	21.0	37.7	57.9
OSEM-BW	4	14.2	20.2	37.9	58.1
C
AR-OSEM-AR	0	20.2	23.9	40.9	63.2
BW-FBP	0	18.5	21.1	40.6	61.7
OSEM-BW	0	16.8	23.2	40.3	62.3
AR-OSEM-AR	2	15.8	19.5	39.0	58.6
BW-FBP	2	16.9	20.8	38.6	58.7
OSEM-BW	2	16.5	20.3	39.1	58.6
AR-OSEM-AR	4	12.5	19.0	37.6	58.2
BW-FBP	4	14.0	19.6	36.8	58.0
OSEM-BW	4	13.8	19.3	37.4	57.9

A: low count level; B: intermediate count level; C: high count level; AR-OSEM-AR: autoregressive filtering before and after ordered subset expectation maximisation algorithm; BW-FBP: Butterworth prefiltering and filtered back projection; OSEM-BW: ordered subset expectation maximisation algorithm and Butterworth postfiltering; RelAct: activity relative to background activity of 1; Ø: diameter.