Radiation therapy is indicated for nearly 50% of cancer patients in Australia. Radiation
therapy requires accurate delivery of ionising radiation to the neoplastic
tissue and pre-treatment in situ x-ray imaging plays an important role in meeting
treatment accuracy requirements. Four dimensional cone-beam computed tomography
(4D CBCT) is one such pre-treatment imaging technique that can help to
visualise tumour target motion due to breathing at the time of radiation treatment
delivery. Measuring and characterising the target motion can help to ensure highly
accurate therapeutic x-ray beam delivery.
In this thesis, a novel pre-treatment x-ray imaging technique, called Respiratory
Triggered 4D cone-beam Computed Tomography (RT 4D CBCT), is conceived and investigated.
Specifically, the aim of this work is to progress the 4D CBCT imaging
technology by investigating the use of a patient’s breathing signal to improve and
optimise the use of imaging radiation in 4D CBCT to facilitate the accurate delivery
of radiation therapy.
These investigations are presented in three main studies:
1. Introduction to the concept of respiratory triggered four dimensional conebeam
2. A simulation study exploring the behaviour of RT 4D CBCT using patientmeasured
3. The experimental realisation of RT 4D CBCT working in a real-time acquisitions
The major finding from this work is that RT 4D CBCT can provide target motion
information with a 50% reduction in the x-ray imaging dose applied to the patient.