ESTRO 2024 - Abstract Book

S3793

Physics - Image acquisition and processing

ESTRO 2024

The number of annotated slices with poor visibility was significantly smaller for HyperSight CBCT imaging compared to conventional CBCT imaging (p-values: <0.001). The number of annotated sliced with poor visibility decreased from a median of 5 for conventional CBCT to 1 for HyperSight CBCT for prostate, from 2 for conventional CBCT to 0 for HyperSight CBCT for bladder, from 3 for conventional CBCT to 0 for HyperSight CBCT for rectum and from 2 for conventional CBCT to 0 for HyperSight CBCT for seminal vesicles.

For 100% of the HyperSight CBCTs, image quality was scored sufficient for online adaptive radiotherapy, compared to 63% of the conventional CBCTs.

Conclusion:

In this study for prostate cancer patients, the HyperSight CBCT showed significantly better image quality compared to the conventional Ethos CBCT. Prostate, seminal vesicles, bladder and rectum were all better visible on HyperSight CBCTs. Furthermore, observers indicated to have less doubt when delineating these structures on the HyperSight CBCT compared to the conventional Ethos CBCT. In contrast to the conventional Ethos CBCT, the HyperSight CBCT was considered suitable for an online adaptive workflow in all cases. These results led to the decision to have all patients with an online adaptive treatment for prostate or rectum tumors at our institute treated on our Ethos machine with HyperSight CBCT. Furthermore, we now treat prostate cancer patients who are not eligible for marker implantation on the Ethos with HyperSight CBCT without increasing CTV-PTV margins.

Keywords: HyperSight, Ethos, image-guided adaptive RT