ESTRO 2024 - Abstract Book

S3771

Physics - Image acquisition and processing

ESTRO 2024

Fig.2. The CBCT HU/pixel value = f(ED) curves for the CIRS and RMI phantoms converted vs CT HU/pixel value = f(ED) curves.

The performed analysis showed that the conversion ensured matching between CBCT data and CT data for both phantoms. The relation between CBCT and CT data can be clearly identified via the conversion functions. Significant differences were found for the HU/pixel value = f(ED) curves between phantoms, specifically above RED>1.1.

Conclusion:

The CBCT calibration process allowed to establish the function HU/pixel value = f(ED) and find the relationship between CBCT and CT modalities, where the latter is treated as the gold standard for TPS and tissue characterization for radiotherapy planning purposes. This potentially enables the use of CBCT data for planning/re-planning purposes and the adaptation of radiotherapy plans. It can also be used to assess differences between calculated dose distributions compared to the original radiotherapy plan to support decision-making about continuing the radiotherapy treatment. Further investigations for clinical CBCT scans and cases will be conducted.