Nano X Image Guidance in Radiation Therapy: cone beam computed tomography imaging with gravity induced motion

Abstract BackgroundThis paper describes the protocol for the Nano X Image Guidance (Nano X IG), a single-institution, clinical imaging study. The Nano X is a prototype fixed-beam radiotherapy system developed to investigate the feasibility of a low cost, compact radiotherapy system to increase global access to radiation therapy. This study aims to assess the feasibility of volumetric image guidance with Cone Beam Computed Tomography (CBCT) acquired during horizontal patient rotation on the Nano X radiotherapy system.MethodsIn the Nano X IG study we will determine whether image guidance can be performed with the Nano X radiotherapy system, to a clinically acceptable and usable standard for radiotherapy. We will acquire both conventional CBCT scans and Nano X CBCT scans, where the patient is horizontally rotated while scan projections are acquired, for 30 patients. For each patient a panel of experts will assess the image quality of Nano X CBCT scans against conventional CBCT scans. Each patient will receive two Nano X CBCT scans to determine the image quality reproducibility, the extent and reproducibility of patient motion and assess patient tolerance.DiscussionFixed-beam radiotherapy systems have the potential to help ease the current shortfall and increase global access to radiotherapy treatment. Advances in image guidance could facilitate fixed-beam radiotherapy using horizontal patient rotation. The efficacy of this radiotherapy approach is dependent on our ability to image and adapt to motion due to rotation and for patients to tolerate rotation during treatment.Trial registrationThis study was registered on ClinicalTrials.gov on 27 July 2020. The identifier is: NCT04488224.