Halo Algorithm Workflow
The steps of the halo algorithm are described in the following table. As described above, in certain cases, the amount of coverage reduction and therefore the halo might be updated multiple times throughout the optimization.
The Desired Coverage Volume for the PTV is used to normalize the treatment plan.
The OAR constraint of the Most Important OAR is set to Strict and is violated.
PTV coverage is reduced based on the amount of violation.
This reduced coverage is translated into a halo radius.
Voxels within the PTV that are covered by the halo are marked as “to be sacrificed”.