Radiographic Determination of Mass of Inertial Tensors of Anatomical Segments

摘要

The intent of this study is to investigate the practicality and potential accuracy of the use of radiographic techniques to determine properties of anatomical segments - mass, center of gravity, and the inertial tensor. Three orthogonal projections (x-ray photographs) through the segment will determine these properties is sufficiently high energy x-rays are used so that attenuation is independent of atomic number and just dependent on mass density. This occurs above a few hundred keV energy. A radioactive source is preferable to an x-ray because radioactive source (1) can have higher energy; (2) is monochromatic (single energy); (3) is less expensive and smaller than tubes making the exposure set up less expensive and simpler; (4) is more easily shielded than is a machine because of the small size of the source. The study goes on to determine the required exposure time and dose; and exposure configuration. Multiple exposures of the anatomical segments are desired alone with non-orthogonal views as to better isolate a given segment. For example, the head is connected to the body by the neck. If the mass properties are desired above a given reference (say a specified vertebrae) and if one could severe the head at the point and float it in space, one could easily take 3 orthogonal views, each encompassing the entire head. In addition to these consideration, the authors are concerned with beam spreading (parallax, fan beam) plan touse a source close to the segment.