Send to

Choose Destination
Radiother Oncol. 2001 Sep;60(3):273-80.

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.

Author information

Department of Medical Physics, The Norwegian Radium Hospital, University of Oslo, Box 20, 0310 Oslo, Norway.



To evaluate variation of dose to organs at risk for patients receiving fractionated high dose rate gynaecological brachytherapy by using CT-based 3D treatment planning and dose-volume histograms (DVH).


Fourteen patients with cancer of the uterine cervix underwent three to six CT examinations (mean 4.9) during their course of high-dose-rate brachytherapy using radiographically compatible applicators. The rectal and bladder walls were delineated and DVHs were calculated.


Inter fraction variation of the bladder volume (CV(mean)=44.1%) was significantly larger than the inter fraction variation of the mean dose (CV(mean)=19.9%, P=0.005) and the maximum dose (CV(mean)=17.5%, P=0.003) of the bladder wall. The same trend was seen for rectum, although the figures were not significantly different. Performing CT examinations at four of seven brachytherapy fractions reduced the uncertainty to 4 and 7% for the bladder and rectal doses, respectively. A linear regression analysis showed a significant, negative relationship between time after treatment start and the whole bladder volume (P=0.018), whereas no correlation was found for the rectum. For both rectum and bladder a linear regression analysis revealed a significant, negative relationship between the whole volume and median dose (P<0.05).


Preferably a CT examination should be provided at every fraction. However, this is logistically unfeasible in most institutions. To obtain reliable DVHs the patients will in the future undergo 3-4 CT examinations during the course of brachytherapy at our institution. Since this study showed an association between large bladder volumes and dose reductions, the patients will be treated with a standardized bladder volume.

[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Elsevier Science Icon for Norwegian BIBSYS system
Loading ...
Support Center