Planimetric volumetry of the prostate: influence of the step size

Planimetric volumetry is often used in clinical practice for accurate prostate volume determination. The prostate volume is determined by discretization of the 3D prostate shape. The area of the prostate is calculated in consecutive ultrasonographic cross-sections. The area is multiplied with the distance between the cross-sections and the total volume is determined by summation of all contributions. The accuracy of this method depends, among other things, on this distance. This paper describes influences of the distance on the accuracy of volume determination using a prostate model. This theoretical influence is compared to clinical prostate volume determinations for 56 patients using planimetric volumetry with different step sizes