Skip to main content
Diagnostic Imaging Europe. The European portal for diagnostic imaging.
Full Paper

Comparative analyses of the dynamic properties of the rectum studied by cryo-sections of human cadavers and pelvic CT scans of patients

Published Online:


Optimization of radiotherapy treatment plans based on dose–volume histograms relies on accurate organ delineation. Hollow organs, such as the rectum, are difficult and time-consuming to delineate owing to unclear visualization of the border between wall tissue and filling. Automated hollow organ delineation would be a valuable tool, but its development depends upon improved understanding of the dynamics of the rectum in response to filling. Two reasonable assumptions proposed in the literature are that (1) the rectal wall tissue along a constant length of the rectal cylinder is preserved over time and (2) the rectal wall tissue is distributed homogeneously along the cylinder. Therefore, variations in wall thickness can be explained by variable rectal filling. To investigate these assumptions, transversal cross-sectional areas enclosed by the outer contour (Aout) and inner contour (Ain) of the rectum were recorded from digital photographs of cadaver cryo-sections from the U.S. National Library of Medicine's Visible Human Project. In addition, Aout and Ain were recorded from 19 CT scans of 5 of our own patients. The transversal cross-sectional area of the wall of the rectum, Awall=AoutAin, was calculated. The data derived both from cryo-sections and repetitive CT scans of patients, revealed that there was a significant correlation between Awall and Aout, in contradiction to assumption (1) stated above (male cryo-sections: p<0.001, female cryo-sections: p=0.03, repetitive CT scans p<0.001). Moreover, the mean Awall calculated from one CT scan differed significantly from the mean Awall from other CT scans and was correlated with the mean Aout, i.e. rectal filling (p<0.001). This finding was confirmed by careful analysis of another study (p=0.001) and opposes assumption (2). Hence, the amount of wall tissue within a constant length of rectum is not preserved over time, but increases with increased filling. This implies that the longitudinal length of the rectum decreases in response to distension of the organ.


  • 1 Lebesque JV, Bruce AM, Kroes APG, Touw A, Shouman T, Van Herk M. Variation in volumes, dose-volume histograms, and estimated normal tissue complication probabilities of rectum and bladder during conformal radiotherapy of T3 prostate cancer. Int J Radiat Oncol Biol Phys 1995;33:1109–19. Crossref Medline ISIGoogle Scholar

  • 2 Lu Y, Li S, Spelbring D, Song P, Vijayakumar S, Pelizzari C, Chen GTY. Dose-surface histograms as treatment planning tool for prostate conformal therapy. Med Phys 1995;22:279–84. Crossref Medline ISIGoogle Scholar

  • 3 Lu Y, Song PY, Li S, Spelbring DR, Vijayakumar S, Haraf DJ, Chen GTY. A method of analyzing rectal surface area irradiated and rectal complication in prostate conformal radiotherapy. Int J Radiat Oncol Biol Phys 1995;33:1121–5. Crossref Medline ISIGoogle Scholar

  • 4 Li S, Boyer A, Lu Y, Chen GTY. Analysis of the dose-surface histogram and dose-wall histogram for the rectum and bladder. Med Phys 1997;24:1107–16. Crossref Medline ISIGoogle Scholar

  • 5 Ting JY, Wu X, Fiedler JA, Yang C, Watzich ML, Markoe A. Dose-volume histograms for bladder and rectum. Int J Radiat Oncol Biol Phys 1997;38:1105–11. Crossref Medline ISIGoogle Scholar

  • 6 MacKay RI, Hendry JH, Moore CJ, Williams PC, Read G. Predicting late rectal complications following prostate conformal radiotherapy using biologically effective doses and normalized dose-surface histograms. Br J Radiol 1997;70:517–26. Link ISIGoogle Scholar

  • 7 Meijer GJ, Van den Brink M, Hoogeman MS, Meinders J, Lebesque JV. Dose wall histograms and normalized dose surface histograms for the rectum. A new method to analyze the dose distribution over the rectum in conformal radiotherapy. Int J Radiat Oncol Biol Phys 1999;45:1073–80. Crossref Medline ISIGoogle Scholar

  • 8 Pedersen D, Bentzen SM, Overgaard J. Early and late radiotherapeutic morbidity in 442 consecutive patients with locally advanced carcinoma of the uterine cervix. Int J Radiat Oncol Biol Phys 1994;29:941–52. Crossref Medline ISIGoogle Scholar

  • 9 Schulteiss TE, Hanks GE, Hunt MA, Lee WR. Incidence of and factors related to late complications in conformal and conventional radiation treatment of cancer of the prostate. Int J Radiat Oncol Biol Phys 1995;32:643–9. Crossref Medline ISIGoogle Scholar

  • 10 Hellebust TP, Dale E, Skjønsberg A, Olsen DR. Inter-fraction variations in rectum and bladder volumes and dose distributions during high dose rate brachytherapy treatment of the uterine cervix investigated by repetitive CT-examinations. Radiother Oncol 2001;60:273–80. Crossref Medline ISIGoogle Scholar

  • 11 Larsen RJ, Marx LM. An introduction to mathematical statistics and its applications. Upper Saddle River, NJ: Prentice-Hall, 1986. Google Scholar

Volume 76, Issue 902February 2003
Pages: 89-148

© The British Institute of Radiology


  • RevisedOctober 09,2002
  • ReceivedMarch 21,2002
  • AcceptedNovember 04,2002
  • Published onlineJanuary 28,2014


We thank our LINUX expert Torbjørn Sund, MSc, for invaluable assistance. We are also grateful to Professor Per Holck, Department of Anatomy, Faculty of Medicine, University of Oslo, for fruitful discussions on rectal anatomy.