BLADDER AND RECTUM VOLUME ESTIMATIONS USING CT AND STEREOLOGY

Twelve prostate cancer patients underwent a treatment planning CT prio r to radiotherapy. Stereologic method based on Cavalieri principle was applied to CT images. Systematic and random sampling of CT slices wer e performed with alternative ways for assessing the volumes of bladder and rectum. The contribution of point counting to the precision of th e obtained volume estimations was analysed. It was found that 100-150 test points counted on only 5-7 systematically sampled slices through bladder or rectum suffice for reliable volume estimations of the above organs. Also, the superiority of systematic vs random sampling was co nfirmed. The suggested volumetric method gives the possibility of gene rating unbiased and efficient bladder and rectum volume assessments di rectly from CT data with great saving in labour. (C) 1998 Elsevier Sci ence Ltd. All rights reserved.