.. _sphx_glr_auto_examples_01_pet_geometry:

PET scanner and sinogram geometry examples
------------------------------------------

These examples introduce the geometry objects that every projector is built
from: cylindrical regular-polygon scanners and modular block scanners, how
detector lines of response (LORs) map to sinogram bins, axial compression via
the Michelogram (span and maximum ring difference), and sinogram symmetries.
Start here to understand the building blocks used throughout the other
galleries.


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    <div class="sphx-glr-thumbcontainer" tooltip="This example shows how to create and visualize PET scanners where the LOR endpoints can be modeled as a stack of regular polygons.">

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  .. image:: /auto_examples/01_pet_geometry/images/thumb/sphx_glr_01_run_regular_polygon_pet_scanner_thumb.png
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  :doc:`/auto_examples/01_pet_geometry/01_run_regular_polygon_pet_scanner`

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      <div class="sphx-glr-thumbnail-title">Regular polygon PET scanner geometry</div>
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    <div class="sphx-glr-thumbcontainer" tooltip="In a scanner with &quot;cylindrical symmetry&quot;, all possible lines of response (LORs) between two LOR endpoints can be sorted into a sinogram containing a radial, view and plane dimension. This example shows how this can be done using the .RegularPolygonPETLORDescriptor">

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  .. image:: /auto_examples/01_pet_geometry/images/thumb/sphx_glr_02_run_regular_polygon_pet_sino_thumb.png
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  :doc:`/auto_examples/01_pet_geometry/02_run_regular_polygon_pet_sino`

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      <div class="sphx-glr-thumbnail-title">LOR descriptors and sinogram definition</div>
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    <div class="sphx-glr-thumbcontainer" tooltip="In this example, we show how to setup a generic PET scanner consisting of multiple block modules where each block module consists of a regular grid of LOR endpoints. We also show how to define a LOR descriptor for this geometry using a description of which block pairs are in coincidence.">

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  .. image:: /auto_examples/01_pet_geometry/images/thumb/sphx_glr_03_run_block_scanner_thumb.png
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  :doc:`/auto_examples/01_pet_geometry/03_run_block_scanner`

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      <div class="sphx-glr-thumbnail-title">Modularized (block) PET scanner geometry</div>
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    <div class="sphx-glr-thumbcontainer" tooltip="A Michelogram is a diagram of which ring pairs (s, e) form valid coincidences in a cylindrical PET scanner, and how they are grouped into sinogram planes under Siemens / STIR axial compression conventions.  Ring pairs are sorted by segment (a function of the ring difference rd = e - s) and, within each segment, by axial midpoint s + e.">

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  .. image:: /auto_examples/01_pet_geometry/images/thumb/sphx_glr_04_run_michelogram_and_compression_thumb.png
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  :doc:`/auto_examples/01_pet_geometry/04_run_michelogram_and_compression`

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      <div class="sphx-glr-thumbnail-title">Michelograms and axial sinogram compression</div>
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    <div class="sphx-glr-thumbcontainer" tooltip="For a given sinogram view, a regular polygon PET scanner connects pairs of in-ring detector endpoints in a zig-zag pattern as the radial bin index moves from the central LOR toward the sinogram edges.  Two conventions exist for the ordering of those pairs:">

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  .. image:: /auto_examples/01_pet_geometry/images/thumb/sphx_glr_05_run_zigzag_comparison_thumb.png
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  :doc:`/auto_examples/01_pet_geometry/05_run_zigzag_comparison`

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      <div class="sphx-glr-thumbnail-title">Zig-zag sampling of LORs in a sinogram view</div>
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    <div class="sphx-glr-thumbcontainer" tooltip="A cylindrically-symmetric PET scanner admits five families of symmetry that reduce the number of geometrically distinct sinogram bins This example focuses on the three axial (plane) symmetries and then quantifies the additional gain from the two in-plane symmetries.">

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  .. image:: /auto_examples/01_pet_geometry/images/thumb/sphx_glr_06_run_sinogram_symmetries_thumb.png
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  :doc:`/auto_examples/01_pet_geometry/06_run_sinogram_symmetries`

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      <div class="sphx-glr-thumbnail-title">Sinogram symmetries</div>
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    <div class="sphx-glr-thumbcontainer" tooltip="Mashing groups neighbouring detectors into larger virtual detectors located at the average endpoint position.  By reducing the number of detectors it dramatically reduces the number of lines of response (LORs), which shrinks the sinogram and speeds up reconstruction at the cost of spatial resolution.">

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  .. image:: /auto_examples/01_pet_geometry/images/thumb/sphx_glr_07_run_detector_mashing_thumb.png
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  :doc:`/auto_examples/01_pet_geometry/07_run_detector_mashing`

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      <div class="sphx-glr-thumbnail-title">Detector mashing: fewer, bigger virtual detectors</div>
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    <div class="sphx-glr-thumbcontainer" tooltip="TOF mashing groups neighbouring time-of-flight (TOF) bins into fewer, wider bins.  This shrinks the TOF axis of a sinogram (less memory, faster reconstruction) at the cost of TOF resolution -- completely independent of any detector / LOR mashing along the spatial axes.">

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  .. image:: /auto_examples/01_pet_geometry/images/thumb/sphx_glr_08_run_tof_bin_mashing_thumb.png
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  :doc:`/auto_examples/01_pet_geometry/08_run_tof_bin_mashing`

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      <div class="sphx-glr-thumbnail-title">TOF-bin mashing: fewer, wider time-of-flight bins</div>
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.. toctree::
   :hidden:

   /auto_examples/01_pet_geometry/01_run_regular_polygon_pet_scanner
   /auto_examples/01_pet_geometry/02_run_regular_polygon_pet_sino
   /auto_examples/01_pet_geometry/03_run_block_scanner
   /auto_examples/01_pet_geometry/04_run_michelogram_and_compression
   /auto_examples/01_pet_geometry/05_run_zigzag_comparison
   /auto_examples/01_pet_geometry/06_run_sinogram_symmetries
   /auto_examples/01_pet_geometry/07_run_detector_mashing
   /auto_examples/01_pet_geometry/08_run_tof_bin_mashing