[Organ volume determination by computer tomography. I. The estimation of organ sectional areas with special reference...

With the aid of computer tomography it is possible to determine the volume or organs by obtaining an adequate number of CT cuts through the area of interest, and by marking the organ contours. Various sources of error must be taken into account when using this method; some of these are systematic and others accidental. In particular it must be remembered that there may be errors in obtaining cross-sectional areas from the organ contours, since these vary depending on the chosen parameters, such as window level and position. These relationships, which depend on the apparatus, are developed theoretically and confirmed by measurements. It is shown that errors depend not only on the choice of window level, but also on the shape and size of the organ and on the surrounding contrast. It follows that it is possible to introduce corrections for the cross-sectional area, but that the size and shape of the section need to be taken into account, at least to some extent.