“People with an increased risk of lung cancer may consider annual lung cancer screening using low-dose CT scans. Lung cancer screening is generally offered to older adults who have smoked heavily for many years or who have quit in the past 15 years.  In diagnosing tests may include: Imaging tests. An X-ray image of your lungs may reveal an abnormal mass or nodule. A CT scan can reveal small lesions in your lungs that might not be detected on an X-ray. Sputum cytology. If you have a cough and are producing sputum, looking at the sputum under the microscope can sometimes reveal the presence of lung cancer cells. Tissue sample (biopsy). A sample of abnormal cells may be removed in a procedure called a biopsy.  Once your lung cancer has been diagnosed, your doctor will work to determine the extent (stage) of your cancer.”

MAYO (https://www.mayoclinic.org/diseases-conditions/lung-cancer/diagnosis-treatment/drc-20374627)