To compare the image quality of UGIS (upper gastrointestinal series) obtained by direct radiography with that of UGIS obtained by indirect radiography in a mass screening program for gastric cancer, and to assess the validity of UGIS by indirect radiography.

A total of 994 persons participated in a mass screening test for gastric cancer between March 2003 and April 2003 at the Korea Association of Health Promotion (KAHP). Of these 994 persons, 494 underwent UGIS by direct radiography, while the remaining 500 underwent UGIS by indirect radiography (i.e. photofluorography using a mirror camera and a 100 mm-roll film). We compared the image quality of UGIS obtained by direct and indirect radiography with, in each case, the image quality being graded as 'excellent', 'good', 'fair', 'poor' or 'very poor'.

The image quality of UGIS by both direct and indirect radiography was similar: most images in both groups were rated as either 'excellent', 'good', or 'fair', while the incidences of poorly rated images were similar in both cases (5% versus 6%, respectively); and there were no images rated as 'very poor' in either case. For certain sites of the stomach, the image quality of UGIS by direct radiography was superior to that of UGIS by indirect radiography, namely at the cardia (p<0.001) and duodenum (p=0.001). However, for other sites of the stomach, the image quality of UGIS by both direct and indirect radiography was similar, namely at the body (p=0.043) and pylorus (p>0.05).

There was no significant difference in the image quality between UGIS by indirect and direct radiography. Therefore, UGIS by indirect radiography may be used as a method of mass screening for gastric cancer.