In this trial, Respiratory Motion Guided (RMG) 4DCBCT will be implemented for the first time on lung cancer patients. RMG-4DCBCT adapts the image acquisition as the patient's breathing changes (i.e. if the patient breathes faster, imaging data is acquired faster).

By adapting the acquisition to the dynamic patient, personalised images of a patients lungs are able to be acquired for radiotherapy treatments.

Four dimensional cone beam computed tomography (4DCBCT) continues to play a pivotal role in the safe delivery of radiotherapy treatments for lung cancer patients. 4DCBCT meets exacting tumour localisation requirements by allowing radiation therapists to measure the tumour as a patient breathes (4D=volumetric images plus respiratory induced tumour motion). Despite the success of 4DCBCT to date, it suffers from relatively poor image quality, very long scan times (4min) and higher imaging doses than are necessary. The primary reason for these problems is that although the purpose of 4DCBCT is to acquire information about tumour motion due to respiration, there is no feedback from the patients breathing signal to adapt and optimise the image acquisition process. This clinical trial is a phase 1 first in human's pilot study and the aim is therefore to prove feasibility of RMG-4DCBCT, not necessarily efficacy. As such, patient scans will be acquired across a broad range of patient breathing conditions to optimise the RMG-4DCBCT technique and also to plan a hypothesis driven clinical trial to follow.

Inclusion Criteria:

• Have the ability to give informed consent
• A diagnosis of lung cancer with an indication for radiotherapy either curative or palliative
• Radiotherapy treatment involving the routine acquisition of CBCT for patient setup provided that 4DCBCT is to be acquired during the course of treatment.
• At least two radiotherapy fractions during the course of treatment.

Exclusion Criteria:

• Pregnant women.
• Patient who in the opinion of the treating physician could not tolerate the extra time on the treatment couch for two days of treatment.

Patients with lung cancer who will be treated with radiotherapy.

Only non-identifiable data may be made available for other scientific research, e.g., nonidentifiable data placed on a well-controlled university site, upon request. The data sharing platform is a secure on-line storage solution ("CloudStor") provided through University of Sydney. The data will be stored as a password-protected, encrypted file. In order to download or decompress the data, participating researchers agree to the terms of use for the data, including: (i) that the data is not to be published or otherwise redistributed without the express consent of the original investigators.

Data will become available following completion of the final analysis. Data will be available indefinitely.

Data will be made available to other researchers upon request.