A pantograph for body contours.

When X-ray treatments are being planned, it is necessary to know the body contour. Various methods may be used to obtain a reproduction of this, such as plaster casts, flexible rules or one of the devices which have been designed specially for the purpose (Treherne and Greening, 1952; Spicer, 1954); the contours so obtained have then to be transferred to paper. In the method described here, a direct drawing is made by moving a pointer over the body surface. This pantograph has been designed for drawing body contours of the trunk, with the patient lying down. A scale is provided for measuring the height above the couch of any point of interest, such as the body thickness. In general, the thickness of a patient will differ slightly according to whether he is lying prone or supine, and it has been decided to take, for the purpose of treatment planning, the effective thickness to be the mean of these two measurements.