The authors summarize the present state of detection and demonstration of the etiology of lung nodules. Bronchogenic carcinoma is the main cause of death for malignant diseases in the European Union countries and the U.S.A. and also all over the world. 5 year survival is less than 15%. At the present time there is a large difference between the survival in stage I.A (5 year survival is about 60%) and stage IV (5 year survival less than 1%). Screening low-dose CT studies are performed in Europe and the U.S.A. (a study with 50,000 persons started in 2004). Final results of the prospective, randomized, controlled study related to the outcome of decreasing mortality will be available in 2010 at the earliest. The National Oncologic Register in the Czech Republic has shown that annually 4,589 men and 1,397 women fell ill. The mortality is getting close to incidence – 4,219 men and 1,339 women annually – and bronchogenic carcinoma participates in mortality for tumours with 26%. The authors describe the rule for observation small lung nodules in the group of low and high risk patients in relation to their size by means of computed tomography (CT). The last recommendations of the Fleischner society in 2005 classify the nodules into three groups and recommends suitable intervals for repeated CT. In the introduction of screening for pulmonary carcinoma it is also possible to use the automatic or semiautomatic analysis of images – diagnostics with the help of computer – computer assisted diagnosis (CAD). In addition to giving more precision to the demonstration of small nodules, these systems make it possible to calculate more precisely their volume and changes of volumes during time. The authors present their own results in the development of software in collaboration with Czech Institute of Technology.

        Key words: solitary pulmonary nodule – low-dose CT – semiautomatic image analysis