Determination of body outline by stereo x-ray photogrammetry

The method proposed for taking outlines can be implemented on any simulator or any diagnostic x-ray machine provided that its head can be turned at an angle from the vertical direction. The principle of the proposed method is based on a mathematical analysis in X-ray stereography, applied to position determination of marker points in the human body. A chain composed of lead shot 3 mm in diameter, spaced 1 cm apart, is placed on the patient's body at the position where the contour is to be taken. Two radiography x-ray films are taken from two different angles. The position of every lead shot is derived from its projection on the radiograms. A bigger lead shot was inserted into the chain from which counting begins in a predetermined direction. The contours are digitised, fed into the computer and redrawn on the display monitor in a form suitable for treatment planning purposes. If two contours are required two chains can be placed simultaneously on the body. Results are presented of tests with an Alderson phantom. (author)