Specification of angulated projections in coronary arteriography.

In coronary arteriography cranial and caudal angulations are combined with oblique angulations to obtain additional views. The angulations are obtained with a variety of equipment rotating about different axes. The planes and axes in and about which the patient and equipment rotate are defined and the equipment is grouped according to the axes about which it rotates. It is shown that a simple definition of the angulation of a projection may be obtained using concepts and terminology consistent with current radiological practice. One group of equipment then gives directly from the rotation of its component parts the angles specifying the projection. For other equipment, the angles specifying the projection are calculated and tabulated for angles of rotation of the equipment from 0 to 90 degrees. Thus, equivalent projections for the different equipment may be found and compared.