Digital Computer Determination of a Medical Diagnostic Index Directly from Chest X-Ray Images

Image matrices of chest X-ray films were recorded in digital form on magnetic tape using a flying spot scanner, an analog-to-digital converter, and a digital computer system. These taped images were used as input to the computer which, by means of its stored program, automatically measured the maximum transverse diameter of the heart shadow, maximum transverse diameter of the rib cage shadow, then calculated and printed out the ratio of these two measured values. This is the cardiothoracic ratio, which is a standard diagnostic index employed by physicians for detection of cardiac pathology, e.g., heart enlargement. To our knowledge, this is the first practicable and useful diagnostic index successfully determined directly from an unaltered X-ray film through the use of a digital computer.