Routine search for colonic polyps by high-voltage radiography.

Abstract

Colonic polyps play an important role in the development of cancer. These small growths are frequently discovered in the course of postmortem examinations. Bockus states that they were found by Stewart in 4.19 per cent of 1,815 autopsies, by Felson in 6.4 per cent of 955 postmortem examinations, and by Lawrence in 2.8 per cent of 7,000 autopsies. The radiological incidence is usually much lower, since the barium enema cannot be expected to discover many of these small growths. The detection of colonic polyps roentgenologically can be improved, however, by the routine employment of sensitive methods of examination. Stevenson, Moreton, and Seedorf, and later Moreton, Cooper, and Foegelle, have perfected the technic of double-contrast study originally developed by Fischer and Weber. The use of semitransparent contrast media has been ad vocated by Ledoux-Lebard, Garcia-Calderon and by R. M. Potter. The ad vent of x-ray equipment capable of 120 to 130 kv. has made it possible to demonstrate small colonic growths by penetrating the column of barium with high-voltage roentgen rays. The purpose of this paper is to report on the routine employment of high-voltage radiography in a series of adult patients undergoing general examinations. At our institution a general examination usually includes a roentgen study of the colon. The high-voltage technic requires a barium mixture just dense enough to be fully opaque when fluoroscopy is conducted at 80 to 85 kv. This same mixture will become radiographically transparent at 120 to 130 kv. (Fig. 1). A suspension of this density is usually obtained by adding one part of barium to four parts of water by volume. It must be noted, however, that these proportions are not constant and they should be adjusted to the characteristics of the equipment employed. Once the proper density is found, the proportions of barium and water should be carefully controlled. We use a densitometer for this purpose, but the same result may be obtained by mixing known amounts of barium and water in quantities sufficient for the day's work. The high-voltage radiographic exposure should be such as to show one loop of the colon through another (Fig. 2), and it is best controlled by phototiming. If the density of barium is properly balanced against the quality of the roentgen rays, polyps will appear as translucent shadows just as cholesterol stones are visualized by the gallbladder dye (Fig. 3). Since translucent shadows may also be caused by gas or fecal material, the preparation of the patient is extremely important. Two ounces of castor oil are given the evening preceding the examination, and in the morning a number of cleansing enemas are administered in the x-ray department by specially trained personnel. The actual examination is divided into two distinct phases. During the first phase the rectosigmoid is filled and examined under fluoroscopy.