Data analysis of pelvic organs in radiotherapy for cervical cancer

Objective To observe the different distances from pelvic organs（such as uterus, rectum and bladder） to body median line, and to find whether the body median line can completely shield the rectum during routine radiotherapy for cervical cancer. Methods CT images of 25 cervical cancer patients were analyzed. The distances from body median line to bilateral uterine neck and fundus, rectum, bladder edge and ureter, were measured respectively. Results The distance from the body median line to the left and right sides of uterine neck and fundus, rectum and ureter margins was 14.74-50.84（31.42±8.93）mm and 0-49.9（26.32±13.60）mm, 7.57-61.80（29.62±14.96）mm and 1.76-51.38（25.22±16.46）mm,-7.90-29.12（13.79±7.53）mm and 3.80-28.91（12.38±9.91）mm, 23.12-50.00（41.77±7.25）mm and 22.74-55.97（45.31±7.54）mm, respectively. The distance from the body median line at L4 to the left and right ureter was 12.73-43.19（32.44±6.85） and 26.70-48.41（33.02±5.11）mm, respectively. Conclusion The rectum cannot be protected in 32% of cervical cancer patients when pelvic cavity is irradiated using a 4cm shield at the body median line.