| As patients with cervical cancer become younger,the preservation of ovarian function is a guarantee of well-being for patients later in life.In radiotherapy,the distance between the ovary and the target area and the irradiated dose to the ovary are key factors affecting ovarian function.Increasing the distance between the ovary and the target area,controlling the irradiated dose and applying appropriate radiotherapy techniques are of great clinical importance in developing and adjusting treatment plans.In this paper,we investigate the relationship between the tolerated dose of radiotherapy to the ovary and ovarian function in cervical cancer radiotherapy,calculate the positional errors generated by using different positional techniques and statistically obtain the extrapolation values based on megavoltage CT(MVCT)guided spiral tomography radiotherapy techniques in cervical cancer radiotherapy to determine the best positional fixation technique for determining cervical cancer radiotherapy,and apply the results of the tolerated dose to the ovary with the extrapolation values of the target area.The results of the tolerance dose to the ovary were applied to the target area outreach values,and the results were used to produce a new technique based on three techniques:intensity modulated radiation therapy(IMRT),volume modulated arc therapy(VMAT)and spiral tomotherapy(TOMO).The aim of this study is to provide guidance for the clinical application of radiotherapy for cervical cancer with preservation of ovarian function.(1)One hundred and thirty-four patients with postoperative cervical cancer treated with TOMO at Zhejiang Cancer Hospital from January2018 to May 2020 were collected,and each patient underwent MVCT scanning before treatment,and the image alignment was counted and the positional error data in the anterior-posterior(X-axis),left-right(Y-axis),up-down(Z-axis)and cross-sectional rotation(Roll)directions were recorded,and the target area(PTV)outgrowth was calculated by the The PTV extrapolation values were calculated using the PTV boundary formula,and the application of both the thermoplastic membrane and vacuum pad positioning techniques were evaluated.The analysis of MVCT image guidance before each treatment with the TOMO technique can reduce the positional error,and the recommended PTV outgrowth values for the TOMO technique were calculated to be 9 mm,13 mm and14 mm,and the thermoplastic body mould had better positional repeatability;(2)Data were collected from 77 patients who had undergone radiotherapy for cervical cancer with preserved ovarian function in Zhejiang Cancer Hospital and had complete recent follow-up,and ovarian dosimetry parameters were recorded.The intra-ovarian function was compared before,3 months after and 1 year after radiotherapy,and it was concluded that the ovaries would experience transient functional decline or complete failure after a certain radiation dose,and the tolerated dose for ovarian function protection in radiotherapy for cervical cancer was recommended to be Dmax <400 c Gy,V3 <40% and Dmean limitation.The dose prescribed for each plan was4500 c Gy/25 F.The dose parameters of PTV and other organs at risk were recorded and analyzed to compare the differences between the three techniques in cervical cancer radiotherapy plans for the protection of ovarian function,and a preliminary proposal for The TOMO technique is more recommended in the case of ovarian tolerated doses that preserve ovarian function during radiotherapy.The above results provide clinical guidance on the tolerated dose of radiotherapy for ovarian protection in cervical cancer,and have some reference value in terms of positional errors in the TOMO technique for ovarian protection in cervical cancer,providing a reference for the specific operation of ovarian protection in radiotherapy for cervical cancer. |
