Comments on Kalender et al.: A PC program for estimating organ dose and effective dose values in computed tomography. Europ. Radiology 2001; 11: 2641 - 2642 und Kalender WA, Schmidt B. Reply to D. Tack: A PC program for estimating organ dose and effective dose values in computed tomography. - Tack,D. (Europ Radiol, 2001)