In most countries there are specialists in lung diseases. The specialism dates from the days when tuberculosis was still widespread. Nowadays the scope of this specialism has moved towards asthmatic conditions and lung cancer. Special tests to detect lung diseases are X-ray pictures, lung-function tests such as spirometry and bronchoscopy, in which a flexible periscope is inserted in the main airway and lesions can be directly seen. The thoriac surgeon is a specialist who concentrates on the chest and its contents. Operation techniques are special because sometimes vital functions must be taken over by machines.