ESTRO 2024 - Abstract Book

S4833

Physics - Quality assurance and auditing

ESTRO 2024

variance as a function of the reconstruction algorithm, with an average value of 6.05 HU for the iCBCT and 6.72 HU for common reconstruction. In terms of the scattering of the HU parameters measured in the material inserts, the standard deviation increases proportionally with increasing relative electron density. Comparing the standard deviation of HU values obtained by conventional reconstruction, larger values were obtained than using iCBCT.

Furthermore, the application of the iCBCT reconstruction algorithm has a relevant impact on noise reduction, while 43.57 HU was measured with the conventional reconstruction method, 34.34 HU was measured with iCBCT.

Conclusion:

The image quality of extended CBCT acquisitions was not quite affected by the longitudinal offset from the isocenter. Consequently, the offsets have no impact on contouring because the same image quality is encountered throughout the entire scan length. Inward longitudinal movements - i.e. when the patient is moved towards the gantry - have less effect on image quality. From a noise reduction point of view, the subcategorization of the iCBCT reconstruction algorithm is a preferred option, which improves image quality without increasing the patient's additional dose.

Keywords: extended kV CBCT, longitudinal image consistency

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Proffered Paper

National benchmarking of lung SABR and breast radiotherapy treatment plans using cloud-based ProKnow

John Byrne, Samantha Warren, Chris Walker