The VERO® SBRT System radiation machine had water damage and could not be repaired.

Stereotactic Body Radiotherapy (SBRT) delivers an ablative dose of radiation to tumours, with high precision. This technique offers an alternative to surgery for lung lesions. The UZ Brussel of the VUB developed with the support of the Hercules foundation (grant for heavy research infrastructure) in collaboration with Brainlab AG a breathing-synchronized radiation technique on the VERO SBRT system, where the radiation beam follows the moving target (dynamic tumour tracking). The implantation of a marker in the tumour is thereby mandatory for its visualization but excluding patients with poor pulmonary function. Therefore Brainlab® recently released an update of the VERO SBRT system that allows "Markerless Tracking". This markerless technique is currently being implemented at the Radiotherapy Department of UZ Brussel for lung lesions. Hence we plan an observational study that will document the outcome of and feasibility for patients with lung lesions treated with markerless tracking on the VERO SBRT system at the Radiotherapy Department in UZ Brussel.

Stereotactic Body Radiotherapy (SBRT) delivers an ablative dose of radiation to tumours, with high precision. This technique offers an alternative to surgery for lung lesions. The movement of these tumours represents a clinical problem and a technological challenge. The UZ Brussel of the VUB developed with the support of the Hercules foundation (grant for heavy research infrastructure) in collaboration with Brainlab AG a breathing-synchronized radiation technique on the VERO SBRT system, where the radiation beam follows the moving target (dynamic tumour tracking). The implantation of a marker in the tumour is thereby mandatory for its visualization but excluding patients with poor pulmonary function. Moreover, the placement of such an implanted fiducial marker is contraindicated for about 30% of the patients and may be associated with complications such as pneumothorax and bleeding.

Therefore Brainlab® recently released an update of the VERO SBRT system that allows "Markerless Tracking" (MLT). This markerless technique is currently being implemented at the Radiotherapy Department of UZ Brussel for lung lesions. Within the Spearhead Strategic Research Program "Societal Benefit of Markerless Stereotactic Body Radiotherapy: a Statistical Support based on Quantitative Imaging", the investigators aim at evaluating the implementation of this technique focusing on patient outcomes and clinical feasibility. In order to do so they plan an observational study that will document the feasibility and outcome of patients with lung lesions treated with markerless tracking on the VERO SBRT system at the Radiotherapy Department in UZ Brussel.

Inclusion Criteria:

1. Primary NSCLC patients, stage T1-2bN0M0 (TNM 8th edition)

2. Oligometastatic patients with ≤ 3 lung metastases; SBRT as a primary treatment or as a consolidative treatment after induction chemotherapy;

3. >= 18 years

4. Patients will be recruited via the treating radiotherapist

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   Exclusion Criteria:

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Patients with lung lesions or primary lung cancer