[A quality control of interpretation of rolled radiophotogramme used for mass screening of lung cancer in general habitants--cases difficult-to-diagnose and cases difficult-to-detect].

A mass screening for lung cancer was performed on 1,906,660 general habitants of Chiba Prefecture, using rolled radiophotogrammes (RP), a traditional mass screening method used for tuberculosis. Of those examined, 270 lung cancer cases were found. In order to evaluate the quality of RP interpretation, cases difficult-to-diagnose and cases difficult-to-detect were picked out from the detected lung cancer cases. Difficult-to-diagnose cases were defined as cases in which pulmonary tumor was not suspected in the screening. Among these cases, tuberculosis was the disease most frequently suspected. Thus, we reexamined the RP which were suspected as being tuberculosis or pulmonary tumor. There was no difference between the two diseases in terms of the location of pathological shadows. Isolated small nodular shadows and infiltrating shadows were seen as an indication of tuberculosis, while large nodular shadows were thought to indicate pulmonary tumor. In addition, by retrospectively examining the RP of the cases judged as normal in the screening of the previous year, tumor shadows could be found in 54.2% of the cases. These cases were considered to be difficult-to-detect cases of lung cancer. The tumor shadows of many cases were present in the hilar region in these re-examined X-ray films. It was difficult to recognize these shadows in the rolled X-ray films because small nodular shadows or infiltrating shadows overlapped with the opacities of normal structures. To overcome these problems of difficult-to-diagnose cases and difficult-to-detect cases, the following observations are important. (1) Care should be taken in order to obtain photogrammes with excellent quality.(ABSTRACT TRUNCATED AT 250 WORDS)