 This is a single arm seamless phase III prospective cohort study. Patients with early stage Non-Small Cell Lung Cancer T1-T2N0M0 or those with a single pulmonary metastasis of a known malignancy either following radical treatment or systemic therapy will be offered participation in this study. Participants will have three tumor locator beacons placed with a flexible bronchoscope in the small bronchial airways in proximity 3cm from their lung tumors. These tumor locator beacons will provide real-time positional data and will allow for smaller treatment volumes of Stereotactic Ablative Radiosurgery SABR and also allow for a specialized form of treatment delivery known as respiratory gated SABR. This is expected to result in higher precision radiotheapy delivery with less radiotherapy dose to healthy tissues which are in close proximity to the lung tumours. 