Color-additive subtraction.

Abstract

Conventional radiographs remain the most valuable method of recording the x-ray image. Black-and-white subtraction has greatly enhanced the quality of arteriographic studies. Color-additive subtraction is an embellishment of the standard radiographic subtraction. It is a display method of particular value for medical illustrative material and medical teaching. The method outlined below represents a new simplified technic of producing color-additive radiographs. The procedure is significant in that it is simple and relatively inexpensive. The quality of color presentation is excellent. The method is significantly different from the previously described technics (1, 4-6) in that it is a contact process and is capable of producing superior radiographic detail. Method The technic used for producing color-additive subtraction films is summarized in point form as follows: I. Initial Black-and-White Subtraction A. Mask Production 1. Place a sheet of Kodak commercial film (Estar thick base), emulsion side up, directly below a light source. 2. Place the preliminary film (no contrast material) over the commercial Estar film. 3. Place a sheet of clear glass over the two sheets of film to ensure proper film contact. 4. Expose the films to a 15-watt light source for three seconds at a distance of 6 feet. 5. The exposed Kodak commercial film (Estar thick base) is then processed through the R.P. X-Omat processor. B. Superimposition of Mask and Contrast-Filled Film 1. Select a contrast-filled film to be subtracted, and place it on a view box in the normal viewing position. 2. Align the mask and the contrast-filled film so that they are perfectly superimposed. 3. When the alignment is correct, secure the films together with tape. C. Production of the Subtracted Film 1. Place a sheet of Kodak commercial film (Estar thick base) with the emulsion side up directly below a light source. 2. Place the aligned pair of films over the commercial Estar film. 3. Place a sheet of clear glass over the three films to ensure good film contact. 4. Expose films to a 15-watt light source for eight seconds at a distance of 6 feet. 5. The exposed Kodak commercial film (Estar thick base) is then processed through the R.P. X-Omat processor. II. Color-Additive Process A. Background Blue Copy 1. Use the same contrast-filled film as is employed in obtaining the black-and-white subtraction. Place over this film a sheet of blue ultra-high-speed Diazo film.2 The two sheets are then fed into a Blu-Ray white printer, exposing the color foil to ultraviolet light. 2. The exposed sheet of color foil is now fed into a Blu-Ray developer which dry-develops the foil by use of ammonium fumes. 3. The background film shows the general anatomy in light blue with the contrast-filled vessels appearing white.