Computed Tomography (CT) and Lung Function Data Collection for Computational Fluid Dynamics (CFD) in Chronic Obstructive Pulmonary Disease (COPD) Patients

Inclusion Criteria: 1. Patients with documented COPD based on the following criteria: * Smoking history of at least 10 pack-years. * Decreased Tiffeneau index (FEV1/(F)VC \< 0.70). 2. Patients aged ≥ 40 years. 3. Patients should present moderate to very severe COPD with an FEV1 \< 80% of predicted (GOLD 2, 3 and 4). 4. Patients should be treated according to GOLD guidelines. 5. Maintained on stable respiratory medications for 4 weeks prior to visit 1 6. Able to perform lung function tests. Exclusion Criteria: 1. Patients below the age of 40. 2. Patients who are pregnant or are breast-feeding. 3. A respiratory infection or exacerbation of COPD in the four weeks prior to screening. 4. BMI \> 35 kg/m². 5. Patients treated with BiPAP or CPAP. 6. Known active tuberculosis. 7. A history of asthma, cystic fibrosis, central bronchiectasis, interstitial lung disease or pulmonary thromboembolic disease. 8. A history of thoracotomy with pulmonary resection. 9. Active or untreated malignancy.