A 2D antiscatter grid and scatter sampling based CBCT method for online dose calculations during CBCT guided radiation therapy of pelvis

TL;DR

This paper introduces a novel CBCT imaging pipeline that enhances HU accuracy for online dose calculations in pelvis radiation therapy, enabling precise dose delivery verification and plan adaptation.

Contribution

The paper presents a new CBCT pipeline combining data correction and scatter rejection, achieving high HU accuracy comparable to planning CT for online dose calculations.

Findings

Quantitative CBCT pipeline reduces dosimetric errors.

Clinical CBCT shows significant errors compared to the proposed method.

Pipeline enables accurate online dose monitoring.

Abstract

Online dose calculations before radiation treatment have applications in dose delivery verification, plan adaptation, and treatment planning. We propose a novel CBCT imaging pipeline to enhance accuracy. Our approach aims to improve HU accuracy in CBCT images for more precise dose calculations. A quantitative CBCT pipeline was implemented, combining data correction strategies and scatter rejection, achieving high CT number accuracy. We evaluated the pipeline's effect using pelvis anatomy phantoms and found that dosimetric errors in quantitative CBCT-based dose calculations were minimal. In contrast, clinical CBCT and high-performance ASG CBCT-based plans showed significant errors. The proposed quantitative CBCT pipeline offers comparable dose calculation accuracy to the gold-standard planning CT, eliminating the need for density overrides and enabling precise dose delivery monitoring or online plan adaptations in radiation therapy.