| Reason for the Action |
In RayStation, a dose distribution calculated on one image set can be mapped to another using deformable registration. This can be useful when evaluating the effect of a previously delivered dose when planning new treatment.
When a dose is deformed using a deformable registration that expands outwards near the boundary of the original dose grid, parts of the deformed dose may extend beyond the boundary, meaning clinically relevant dose may be excluded from the deformed dose distribution. If this deformed dose is subsequently used as background dose, the missing dose contribution will be treated as zero dose, potentially resulting in an underestimation of the accumulated dose.
This situation requires substantial anatomical differences between the reference and target image sets. Examples include significant weight gain, growth in paediatric patients, or other anatomical changes that increase the extent of the anatomy beyond the region covered by the original dose grid.
For reirradiation planning, the problem may lead to underestimation of the accumulated dose to organs at risk. For adaptive planning, it may lead to underestimation of the accumulated dose to the target and/or organs at risk. |