[Gate-users] ECAT7 output with user defined scanner
COMTAT Claude
claude.comtat at cea.fr
Wed Oct 2 11:20:50 CEST 2013
Hi Johannes,
The problem is that some data that are required to reconstruct an image are missing in the ECAT7 header. An example is the ring diameter. It is not possible to store the ring diameter in a ECAT7 file (neither the number of detectors per ring).
As STIR requires this information, it has a database for each known scanner model. What is printed at the end of your email is not the content of the ECAT7 header, but the content of STIR database:
WARNING: ECAT7 IO: Bin size from header.x_resolution (2.00714) does not agree with expected value 2.25
for scanner ECAT 962. Using bin size from header...
Info for file yourSinogram.S
ProjDataInfoCylindricalNoArcCorr :=
Scanner parameters:=
Scanner type := ECAT 962
Number of rings := 32
Number of detectors per ring := 576
Inner ring diameter (cm) := 82.4
Average depth of interaction (cm) := 0.7
Distance between rings (cm) := 0.485
Default bin size (cm) := 0.200714
View offset (degrees) := 0
Maximum number of non-arc-corrected bins := 288
Default number of arc-corrected bins := 288
Number of blocks per bucket in transaxial direction := 3
Number of blocks per bucket in axial direction := 4
Number of crystals per block in axial direction := 8
Number of crystals per block in transaxial direction := 8
Number of detector layers := 1
Number of crystals per singles unit in axial direction := 8
Number of crystals per singles unit in transaxial direction := 24
end scanner parameters:=
As you set the scanner model to zero in your ECAT7 file (#/gate/output/ecat7/system 962 ), STIR does not recognize it. As a consequence, STIR assumes it is an HR+ (default scanner):
WARNING: ECAT7 IO: Couldn't determine the scanner
(Main_header.system_type=0), defaulting to 962.
This might give dramatic problems.
You should define a new scanner model ID in GATE, like /gate/output/ecat7/system 492, and create in STIR the corresponding database. I do not know how to create your own database in STIR.
Claude
De : gate-users-bounces at lists.opengatecollaboration.org [mailto:gate-users-bounces at lists.opengatecollaboration.org] De la part de Johannes Anderl
Envoyé : mercredi 2 octobre 2013 10:49
À : gate-users at lists.opengatecollaboration.org
Objet : [Gate-users] ECAT7 output with user defined scanner
Dear all,
I have a problem concerning the ECAT7 Output.
I would like to simulate a user defined scanner and not the E962 scanner type.
The created yourSinogram.S file still contains the default values (ring diameter, detectors per ring,...) for the E962 scanner model.
Is there a possbility to get this ECAT7 *.S output with the user defined scanner values?
The code for the user defined scanner type can be seen below:
/gate/world/daughters/name ecat
/gate/world/daughters/insert cylinder
/gate/ecat/setMaterial Air
/gate/ecat/geometry/setRmax 44.1 cm
/gate/ecat/geometry/setRmin 42.1 cm
/gate/ecat/geometry/setHeight 21.7685 cm
/gate/ecat/vis/forceWireframe
# B L O C K
/gate/ecat/daughters/name block
/gate/ecat/daughters/insert box
/gate/block/placement/setTranslation 431.0 0.0 0.0 mm
/gate/block/geometry/setXLength 20.0 mm
/gate/block/geometry/setYLength 52.17127 mm
/gate/block/geometry/setZLength 52.17127 mm
/gate/block/setMaterial Air
/gate/block/vis/forceWireframe
# C R Y S T A L
/gate/block/daughters/name crystal
/gate/block/daughters/insert box
/gate/crystal/geometry/setXLength 20.0 mm
/gate/crystal/geometry/setYLength 4 mm
/gate/crystal/geometry/setZLength 4 mm
/gate/crystal/setMaterial LSO
/gate/crystal/vis/setColor yellow
# R E P E A T C R Y S T A L
/gate/crystal/repeaters/insert cubicArray
/gate/crystal/cubicArray/setRepeatNumberX 1
/gate/crystal/cubicArray/setRepeatNumberY 13
/gate/crystal/cubicArray/setRepeatNumberZ 13
/gate/crystal/cubicArray/setRepeatVector 0. 4.0142725 4.0142725 mm
# R E P E A T BLOCK (reproduziert die Box entlang eines Rings)
/gate/block/repeaters/insert linear
/gate/block/linear/setRepeatNumber 4
/gate/block/linear/setRepeatVector 0. 0. 55.17127 mm
/gate/block/repeaters/insert ring
/gate/block/ring/setRepeatNumber 48
The ecat7 code can be seen below:
/gate/output/ecat7/enable
/gate/output/ecat7/verbose 2
/gate/output/ecat7/setFileName yourSinogram
/gate/output/ecat7/describe
/gate/output/ecat7/mashing 2
/gate/output/ecat7/span 103
/gate/output/ecat7/maxringdiff 51
#/gate/output/ecat7/system 962
Looking at the values from the yoursinogram.S using list_projdata_info from STIR shows:
WARNING: ECAT7 IO: Couldn't determine the scanner
(Main_header.system_type=0), defaulting to 962.
This might give dramatic problems.
WARNING: ECAT7 IO: Bin size from header.x_resolution (2.00714) does not agree with expected value 2.25
for scanner ECAT 962. Using bin size from header...
Info for file yourSinogram.S
ProjDataInfoCylindricalNoArcCorr :=
Scanner parameters:=
Scanner type := ECAT 962
Number of rings := 32
Number of detectors per ring := 576
Inner ring diameter (cm) := 82.4
Average depth of interaction (cm) := 0.7
Distance between rings (cm) := 0.485
Default bin size (cm) := 0.200714
View offset (degrees) := 0
Maximum number of non-arc-corrected bins := 288
Default number of arc-corrected bins := 288
Number of blocks per bucket in transaxial direction := 3
Number of blocks per bucket in axial direction := 4
Number of crystals per block in axial direction := 8
Number of crystals per block in transaxial direction := 8
Number of detector layers := 1
Number of crystals per singles unit in axial direction := 8
Number of crystals per singles unit in transaxial direction := 24
end scanner parameters:=
Thanks in advance,
Johannes
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