A feasibility study on utilizing cone-beam computed tomography in dose adaptive radiotherapy

• Main Author: Chang, Chu Hua
• Other Authors: School of Physical and Mathematical Sciences
• Format: Final Year Project
• Language: English
• Published: 2014
• Subjects: DRNTU::Science::Physics::Radiation physics
• Online Access: http://hdl.handle.net/10356/59411
• Institution: Nanyang Technological University

Radiotherapy is the use of radiation in the treatment of cancer, and the workflow of radiotherapy involves a patient undergoing a Computed Tomography (CT) scan, creating treatment plans based on the scan, conducting a Cone-Beam Computer Tomography (CBCT) scan on the patient before treating the patient with radiation beams or sources. The use of CBCT in modern radiotherapy is to ensure that the patient volume is largely similar to that reflected on the treatment plan just before treatment commences. We are however, interested in using CBCT to generate treatment plans just before the treatment for better verification of the original treatment plan. This method is called Dose-Adaptive Radiotherapy (DART). In our investigation, we create calibration curves on a CIRS Model 062 phantom using different plug positions for different curves, creating 5 curves for CT scans and 5 curves for CBCT scans. We then CT and CBCT scan a Radionics Skull phantom and a CIRS 002LFC Lung phantom, using the previously created calibration curves to generate treatment plans from these scans. We export Dose-Volume Histogram (DVH) and dose plane information, and compare our generated treatment plans to reference plans made from the same CT scans, with a clinical calibration curve. From DVH data comparisons, we find that Skull phantom treatment plans are feasible for treatment, but Lung phantom treatment plans are not. On closer inspection, Lung phantom treatment plans only give proper dose coverage to portions of the patient volume and different plans are accurate at different portions. From dose plane comparisons, we find that the global standard deviation of all Lung phantom plans from the reference plans are similar. Based on these findings, we conclude firstly that CBCT in DART for clinical head treatments seems feasible and further studies should be conducted. We also conclude that site-specific calibration curves, applied at different sites of the patient volume when treatment planning, is required for CBCT to be feasible in DART for clinical lung treatments.