Feasibility Analysis Of Hand-free Implantation Guided By Inverse Planning Simulated Annealing For Locally Advanced Cervical Cancer Tissue Interstitial Brachytherapy

Objective:By comparing the dosimetric difference between the manual optimization method and the inverse planning simulated annealing for the treatment of locally advanced cervical cancer with Interstitial brachytherapy,the feasibility of manual implantation and post-installation treatment was discussed,and it provided some guidance for the Interstitial brachytherapy of cervical cancer tissue.Methods:149 Interstitial brachytherapy plans performed by 30 patients with locally advanced cervical cancer who were treated in our hospital from October 2018 to October 2021 were included,and all patients had received external beam radiotherapy.A single prescription dose of 6-7 Gy for Interstitial brachytherapy,1-2 times/week,a total of 1-7 times.A retrospective analysis of 149 post-installation high-dose-rate radiotherapy plans for cervical cancer patients who have received Interstitial brachytherapy after treatment.The Oncentra three-dimensional brachytherapy planning system is used to redesign the after-installation treatment plans that have already been implemented.A Inverse planning simulated annealing,by comparing the clinical dose distribution and the exposure dose to organs at risk of the two plans,to explore the feasibility of the virtual optimized Interstitial brachytherapy plan to guide the freehand implantation of cervical cancer,and to evaluate the virtual optimized Interstitial brachytherapy plan.Results:Included in our hospital from October 2018 to October 2021,30patients with locally advanced cervical cancer underwent 149 Interstitial brachytherapy plans.After reconstructing the treatment plan on the Oncentra three-dimensional brachytherapy planning system,and Comparing the dosimetric differences between the two plans,it was found that the target dose coverage of the two plan optimization methods was D₉₀,D₁₀₀,and V₁₀₀.Compared with the manual plan optimization method,the Inverse planning simulated annealing increased by 0.06Gy,0.29Gy,and1.25%,respectively,and the differences were statistically significant.Significance（P<0.01）;compared with the manual optimization planning method,the dose distribution of the target volume showed better conformity（CI）and better dose distribution uniformity（DHI）,and the difference was Significant statistical significance（P<0.01）.The differences in D_0.01cc,D_1cc,and D_2cc of bladder,rectum,and sigmoid colon were statistically significant（P<0.001）.The radiation doses of the crisis organs in the Inverse planning simulated annealing were lower than those in the optimization plan,and the D_2cc of bladder,rectum,and sigmoid colon decreased respectively.Small 0.19Gy,0.23Gy,0.09Gy.Conclusions:Compared with manual optimization method,the Inverse planning simulated annealing has obvious dosimetric advantages.It not only improves the irradiation dose of the target area on the existing basis,but also improves the conformity of the target area coverage and the uniformity of dose distribution.The exposure dose to normal organs such as rectum and sigmoid colon has been reduced to varying degrees,and it can also reduce the damage and psychological pressure of patients during the treatment process.In the Interstitial brachytherapy of locally advanced cervical cancer,the method of inverse optimization algorithm is used and the Putting it into practice is the next focus of research in clinical practice.