This is a prospective phase II clinical trial with an anticipated total of more than 380 radiotherapy fractions of 15 patients to evaluate optimal margin of iterative cone-beam computed tomography（iCBCT） guided online adaptive radiotherapy （oART） for postoperative treatment of endometrial and cervical cancer. Postoperative endometrial and cervical cancer patients with following characteristics are included in the present study:（a）underwent radical surgery （b）no residual tumor at the resection margin by postoperative pathology（c）pathological findings indicate risk factors but no metastasis (d) adjuvant radiotherapy are prescribe (e)without evidence of para-aortic metastatic lymph nodes. Five patients （almost 125 fractions）treated with oART have the target volume contoured on pre-treatment iCBCTs and end-treatment iCBCTs. Anterior-posterior, lateral, and superior-inferior shifts were calculated and the average shift in all directions was calculated. A clinical target volume (CTV) to planing tumor volume (PTV) expansion is determined and verifies on a validation cohort of 10 patients (almost 250 fractions) treated with oART. Record acute toxicity from the start of treatment to 3 months after treatment.
Online adaptive radiotherapy has demonstrated to be feasible to reduce inter-fractional radiotherapy errors as it re-optimizes treatment plan every fraction. To investigate the extent and value of margin reduction，we conduct a prospective clinical trial to determine the optimal margin and toxicity of smaller margin.