Volume measurement by computed tomography (CT), (2)

The volume of an organ in the living body has been determined by the method of approximation by using such data as the long or short diamether of an organ obtained from X-ray films, radioisotopic images, and ultrasonic images. Since the development of Computed Tomography (CT), there have been various reports on the volumetric methods with CT images. The volumetric method, where the volume of an organ is taken for the sum of the product of the cross sectional area, slice interval and its accuracy, has been studied by the authors with a phantom experiment. The accuracy in its clinical application to the living body was determined with cadavaric kidneys. Errors in volumetry were 8 % and 6.8 % when the slice intervals were 20 mm and 10 mm (slice thickness was 13 mm). These results suggest that this volumetric method using CT is clinically applicable. Several methods for estimating the volume of the kidney from ''certain limited data'' obtained from CT images were studied, and the accuracy as well as its problems was discussed. (author)