[Gate-users] what does each detector pixel record?
D.Leibold at tudelft.nl
Thu Jul 7 16:30:07 CEST 2022
you are welcome. I didn’t help with your subscription issue, though, credits go to David Sarrut <mailto:david.sarrut at creatis.insa-lyon.fr> for that.
On 7 Jul2022, at 16:03, Howard <lomahu at gmail.com<mailto:lomahu at gmail.com>> wrote:
Thank you very much for your swift response to my question. It is very helpful. I will read the document carefully then and learn how to use the information stored in root files. I am also grateful to your help with my earlier question on the subscription issue.
On Thu, Jul 7, 2022 at 3:20 AM David Leibold <D.Leibold at tudelft.nl<mailto:D.Leibold at tudelft.nl>> wrote:
you are using the imageCT output, and according to the docs<https://urldefense.com/v3/__https://opengate.readthedocs.io/en/latest/data_output_management.html?highlight=imageCT*image-ct-output__;Iw!!PAKc-5URQlI!-arevwjGvGnlk0N06QSlf7YAK_z-IAknuLgEJ8hgubc6-IvsTOCCdqcGRjs5k_DiZ-XTcdQZsARpDZyKZA$>:
"The imageCT output is a binary matrix of float numbers that stores the number of Singles per pixel and is produced for each time slice"
Please note that this does reflect what a realistic detector would measure. A common CBCT detector outputs the deposited energy per pixel. To obtain this, you would need to access the root output and convert it to energy integrated projections yourself.
On 7 Jul2022, at 03:40, Howard <lomahu at gmail.com<mailto:lomahu at gmail.com>> wrote:
Hi GATE users,
I have been using GATE to simulate CBCT. One question I have been thinking to ask is: what does each detector pixel (set as the crystal sensitive detector) record, photon energy or photo number?
Let's say the output of each run (one projection angle) is set as:
# Specific CT Image output
What if I use ROOT output format?
# Generic ROOT output
My detector macro is set as follows for your reference.
#### General informations about the scanner
# CT scanner for small animal imaging
# 150 x 200 pixels in one module
# Size of pixels : 0.4 x 0.3 x 3.0 mm3
# Pixels are made up of silicon (no dead space between pixels)
# This scanner is designed to be fixed (the phantom will rotate instead).
# Let's position it perpendicular to the Z axis at a radial distance of 80 mm.
## CTscanner system (this is the encompassing volume)
# This first volume containing the scanner should have the same hard-coded name
# as the one predefined in GATE (here CTscanner)
# Create it as a box that can contain all pixels
# Set it 80 mm away from the center of the world along the Z axis
# Set material Air, and visualize it as a white wire frame
/gate/CTscanner/geometry/setXLength 60. mm
/gate/CTscanner/geometry/setYLength 60. mm
/gate/CTscanner/geometry/setZLength 3. mm
/gate/CTscanner/placement/setTranslation 0. 0. 80. mm # original position
#/gate/CTscanner/placement/setTranslation 0. -80. 0. mm # for parallel computing, 6/10/2022
#/gate/CTscanner/placement/setRotationAxis 1 0 0 # for parallel computing, 6/10/2022
#/gate/CTscanner/placement/setRotationAngle -90. deg # for parallel computing, 6/10/2022
## The first component of the CTscanner is the module
# CTSCANNER # ----> # MODULE #
# Here we will use only one module, so just create it identical to the encompassing volume
/gate/module/geometry/setXLength 60. mm
/gate/module/geometry/setYLength 60. mm
/gate/module/geometry/setZLength 3. mm
## The second component of the CTscanner is the cluster (located inside the module)
# There are 3 possible clusters: cluster_0, cluster_1 and cluster_2
# MODULE # ----> # CLUSTER_0 #
# Here we will use only one type of clusters, so again just create it identical to the mother volume
/gate/cluster/geometry/setXLength 60. mm
/gate/cluster/geometry/setYLength 60. mm
/gate/cluster/geometry/setZLength 3. mm
## The third component of the CTscanner is the pixel (located inside the cluster)
# There are 3 possible pixels, one by cluster: pixel_0 (in cluster_0), pixel_1 (in cluster_1) and pixel_2 (in cluster_2)
# MODULE # ----> # CLUSTER_0 # ----> # PIXEL_0 #
# Here we will use only one type of pixels
# The pixel size is 0.4 x 0.3 x 3 mm3
# Visualize it as a solid object, color of your choice
/gate/pixel/geometry/setXLength 0.4 mm
/gate/pixel/geometry/setYLength 0.3 mm
/gate/pixel/geometry/setZLength 3. mm
# Now we can repeat the pixel inside the cluster
# We want 150 x 200 pixels
# Note: the repeated objects will be automatically centered on the original position of the single volume
# Set the correct number of repeated volumes and the repeat vector
/gate/pixel/cubicArray/setRepeatVector 0.4 0.3 0. mm
## Attach to hard-coded CTscanner system (here only cluster_0 and pixel_0 are used)
# These commands allow GATE to make a link between the arbitrary volumes you defined and the predefined components of
# the system in use (here the CTscanner). It is used to make a link with the output modules associated to the system
## Attach the pixel as the crystal sensitive detector
# This command is used to specify which arbitrary volume is used as the sensitive volume.
# All interactions occuring in this volume can be recorded and analyzed.
Any feedback is greatly appreciated!
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