Dosimetry Research On The Afterloading Brachytherapy Inverse Intensity-Modulated Radiotherapy Of Gynecological Tumor

The radiotherapy played an important role in the treatment of gynecologic tumorradiotherapy. This study will investigate the application value of the AfterloadingBrachytherapy Inverse Intensity-Modulated Radiotherapy of Gynecological Tumor.This study included20patients with cervical cancer. Patients were randomlydivided into A, B two groups,10cases in each. Stage ⅠB2cases, stage Ⅱa4cases,stage ⅡB12cases, stage Ⅲa2cases. Pathological types: Squamous cell carcinoma16cases, Adenocarcinoma4cases. The average age was55.67years (32~65years old).Group A patients received the Afterloading Brachytherapy Inverse Intensity-ModulatedRadiotherapy. The dose optimization technology was the Inverse Planning SimulatedAnnealing (IPSA).The organs at risk (rectum, bladder) were involved in the doselimiting optimization; Group B patients received the usual Afterloading Brachytherapy.The organs at risk (rectum, bladder) were not involved in the dose limiting optimization.Group A and B patients were treated with3applicator for intracavitary irradiation andsynchronous box around4fields isocenter external irradiation, prescription dose46Gy/23F. According to the Manchester system,the prescription dose of A points (2cmabove the cervix,2cm both in the left and right sides of the axis of uterine cavity) was30Gy in5fractions,2times each week. Analysed groups A and B patients about thetarget volume dose distribution, organs at risk (rectum, bladder), short-term curativeeffect and radioactive complications.This study indicated the target volume dose of group A and B were both achievedprescribed dose requirements.The dose conformal and homogeneity index of the targetvolume of group A were better than group B. The0.5～1yr tumor local and regionalcontrol rate of group A patients was more than95%.Organs at risk (rectum, bladder):the maximum dose of rectum and bladder of group A patients were about35%less thangroup B. The75%prescription dose irradiated volume of rectum and bladder of groupA patients were about only1/2of group B. Radioactive complications: group A patientshad RTOG1grade reaction0case, group B patients had RTOG grade1reaction6cases.Clinical symptoms was the increase the number of stool and micturition frequence,mucous stool. Patients in group A had RTOG2grade reaction was0cases, group Bpatients had RTOG grade2reaction were3cases. Clinical symptoms was diarrhea, with or without mucus secretion, frequent and urgent urination, dysuria and bladder spasmpain, which need medication to ease pain. Short-term efficacy: the tumors size of groupA and B patients had both reduced during and after the radiotherapy, efficiency(CR+PR) was more than92%.Therefore, Afterloading Brachytherapy Inverse Intensity-Modulated Radiotherapytechnique has obvious short-term efficacy, better dose conformal and homogeneityindex of the target volume, lower dose of organs at risk, fewer radioactivecomplications. It’s worthy of widely applicated in the gynecological cancer therapy.