Quantifying the Benefit and Measuring Residual Uncertainties of MLC Tracking During the First Clinical Implementation for Lung Cancer Radiation Therapy

Abstract

Radiation therapy is a cancer treatment that involves the use of radiation to kill cancer cells and shrink the tumour. One of the main issues that this field is facing is that of respiratory-induced tumour motion. In the presence of motion, the radiation beam can miss the tumour and instead irradiate healthy tissues leading to radiation toxicities. For these reasons, positional uncertainty associated with motion is generally recognized as intrinsic to radiotherapy.

With the advent of fast computing technology, it is now feasible to treat cancer patients in a safer way, by tracking the position of their tumour and adapting the radiation beam in real-time. This thesis presents the developments of frontier technology for guided lung cancer radiation therapy. More specifically, this research details the first clinical use of multi-leaf collimator (MLC) tracking for lung cancer patients, a technology that can track and adapt to the patient’s breathing pattern during the irradiation. To demonstrate the feasibility and the benefits of MLC tracking, a clinical trial involving a cohort of patients diagnosed with lung cancer was conducted. This clinical trial, called LIGHT SABR, treated seventeen patients with lung implanted electromagnetic transponders with the primary objective to test whether MLC tracking is feasible, and the secondary objective to evaluate transponder implantation safety/migration and potential dosimetric benefits of MLC tracking over ITV-based treatment. The major finding of this work is thesis is that is that MLC tracking can be implemented in a safe clinical environment for patients with fast and erratic tumour motion patterns.