A Case-Based Guide: Demonstrating the Reirradiation Collaborative Group (ReCOG) Consensus for Dosimetric Assessment...

To provide case-based, practical examples outlining step-by-step calculations and documentation for reirradiation (reRT) evaluation. The representative examples demonstrate the application of the Reirradiation Collaborative Group (ReCOG) consensus for dosimetric assessment and reporting in reRT and illustrate how these standards can be implemented in clinical practice.

Two spine reRT cases were selected. Cumulative organ-at-risk doses were assessed using 3 approaches: direct point dose summation, point dose summation within overlap regions, and image registration-based 3-dimensional dose summation. Step-by-step calculations were performed for each approach, and new dose objectives for subsequent planning iterations were derived and compared.

The example reRT cases detail the special medical physics consult process, highlighting different cumulative dose estimation strategies depending on the availability of voxel-based equieffective dose calculation and visualization tools. Selection of an assessment strategy should balance clinical resources with patient-specific considerations. Calculation and visualization of equieffective dose distributions facilitate cumulative dose assessment and strengthen image registration-based methods. If 3-dimensional equieffective dose calculation is not available, anatomically corresponding volumes and doses in each plan contributing to the cumulative dose in the areas of overlap can be determined manually to improve the accuracy of point dose-based summation.

The case examples demonstrate how to apply the ReCOG consensus for dosimetric assessment and reporting in reRT and illustrate multiple strategies for cumulative dose evaluation. This work supports patient care and contributes to enhancing the field's knowledge and delivery of safer reRT.