.. _sphx_glr_generated_autoexamples_03-sequence-optimization:

Sequence optimization
---------------------

Choosing a sequence's parameters rather than simulating the ones you were
given.

A design problem is three pieces: a simulator with the tissue it is designed
for already fixed on it; a cost, which is a plain function of what that
simulator records; and a :class:`~torchsim.SequenceDesign`, which holds the
parameters inside the limits the scanner will play and runs the loop.

Only the cost changes between the first two examples here. One asks for a
picture -- sharp where sharpness is decided, with contrast where contrast is
decided -- and the other asks for precision, choosing flip angles so that T1
and T2 are estimated as tightly as the scan time allows.

The third designs no protocol parameter at all but the samples of an RF pulse,
through a Bloch simulation of the slice it excites, so that the excitation
holds where the transmit field does not.


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    <div class="sphx-glr-thumbcontainer" tooltip="The scope of this notebook is to design refocusing flip angles for image quality rather than for precision: first a single echo train, then a whole segmented 3D protocol in which each shot carries its own repetition time, echo train length and angles.">

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      <div class="sphx-glr-thumbnail-title">Designing echo trains for image quality</div>
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    <div class="sphx-glr-thumbcontainer" tooltip="The scope of this notebook is to choose the flip angles of a DESPOT protocol so that a joint fit of T1 and T2 is as precise as possible [1]_.">

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  :doc:`/generated/autoexamples/03-sequence-optimization/02-joint-relaxometry`

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      <div class="sphx-glr-thumbnail-title">Designing a joint relaxometry protocol</div>
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    <div class="sphx-glr-thumbcontainer" tooltip="The scope of this notebook is to design the samples of an RF pulse directly, by gradient descent through a Bloch simulation of what they do [1]_.">

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  :doc:`/generated/autoexamples/03-sequence-optimization/03-rf-pulse-design`

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      <div class="sphx-glr-thumbnail-title">Designing an RF pulse by optimal control</div>
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.. toctree::
   :hidden:

   /generated/autoexamples/03-sequence-optimization/01-echo-train-design
   /generated/autoexamples/03-sequence-optimization/02-joint-relaxometry
   /generated/autoexamples/03-sequence-optimization/03-rf-pulse-design