Cervical Cancer Patients’ Optimized Ovarian Transposed Site And Protective Measures Of Transposed Ovaries In Radiotherapy

Purpose: Our study aimed to research the optimized ovarian transposedsite of cervical cancer patients who needed postoperative radiotherapy, and toexplore the best protective measures of transposed ovaries in pelvic radiation.Methods: The pelvic box technique radiotherapy of cervical cancerpatients was simulated on the anthropomorphic phantom, and five “ovariantransposed sites” on each of three height levels were selected of the phantom,then we placed LiF thermoluminescence dosimeters at each site in-plane(vertical and parallel to the skin, respectively). In addition, we selected foursites in the middle level and placed dosimeters vertically down to the crosssurface in each site, then the absorbed does of each dosimeter was measuredin this radiotherapy (each radiation field was given equal dosage); in ElektaXio radiotherapy planning system, five “transposed ovaries” on each of sixheight levels were sketched and the absorbed does was assessed;6cervicalcancer patients were selected randomly, and five “transposed ovaries” on eachof two height levels were sketched of each patient, then we formulated twodifferent pelvic radiotherapy plans (each radiation field was given equal andunequal dosage, respectively）and assessed the absorbed does; we used theself-made “lead pimps” of2mmPb,0.35mmPb and the width of5cm,10cm tosurround the phantom, the lower bound of the “lead pimps” was the iliac crestlevel. In the protective mode of each “lead pimps”, the absorbed does of thefour dosimeters put vertically down to the cross surface of3cm above the iliaccrest was measured，respectively. Result:1At the same site of each height level, the dose of dosimeters putrespectively vertical, parallel to the skin was similar; the dose of dosimetersand the radiation planning system had a consistent regularity;2In the phantom, the absorbed dose of “transposed ovaries” fell whileheight levels increased. The absorbed dose of “transposed ovaries”3cm abovethe iliac crest was2.7-3.7Gy (the single measurement value multiplied by25).3At the same height level, the dose of the two “transposed ovaries” nearthe rear was relatively fewer than that of the two near the side in the pelvicbox technique radiotherapy; in the cervical cancer patients’ radiation plans,the data of the two height levels was statistically significant (p＜0.05),respectively.4As for the“lead pimps”, the equivalent of2mmPb, the widths of5cmand10cm could reduce the absorbed dose of13.07%、20.63%, respectively;and the equivalent of0.35mmPb, the widths of5cm and10cm could reducethe absorbed dose of12.95%、-2.93%, respectively.Conclusion:1For cervical cancer patients who will accept the pelvic box techniqueradiotherapy, it is recommended to transpose their ovaries3-4.5cm above theiliac crest at least.2In cervical cancer patients’ pelvic box technique radiotherapy, thedose of the “transposed ovaries” near the rear of the paracolic sulci isrelatively fewer than that of them near the side.3Covering the “lead pimps” on the phantom can reduce the absorbeddoes of “transposed ovaries” to some extent, maybe the protective effect wasrelated to lead equivalent and width.