CTV Exploration of 3D-PT Assisted CT-guided I-125 Seeds Implantation for Recurrent Rectal Cancer

Inclusion Criteria: * KPS score above 60; * Age from 18 to 80 years old; * Rectal cancer by histological diagnosis, recurrence after surgery and radiotherapy; * The diameter of the lesion ≤ 5cm; * The tumor has not invaded the intestines or bladder; * The estimated survival time is more than 3 months; * The percutaneous puncture path is feasible and the preoperative plan can meet the prescription dose; * Blood routine, liver, kidney and other major organ functions: WBC is normal, PLT≥100×109/L, HGB≥100g/L; urea nitrogen, creatinine≤1.25×upper limit of normal (UNL), ALT (SGPT) and AST (SGOT) ≤2.5×UNL; ECG is basically normal; * Recurrence in pelvic region after surgery and radiotherapy for various reasons; or oligo-metastatic lesions less than 3, which are stable with treatment. Except for rectal incision stump and recurrence at the anastomosis. Exclusion Criteria: * Major organ failure, decompensated heart and lung failure such as congestive heart failure, coronary heart disease with clinical symptoms, and arrhythmia that cannot be controlled by drugs; * Patients with other serious uncontrollable medical diseases; * Severe coagulation dysfunction; * With serious infection or ulcer at the puncture site; * Pregnancy, breastfeeding women, children and mental patients; * Patients with severe diabetes; * Cases that invade large blood vessels and vital organs, which may cause hemorrhage and severe organ dysfunction; * Those who have participated in clinical trials of other drugs or medical devices before being selected but have not reached the time limit of the main research endpoint or have completed clinical trials of other drugs or medical devices for less than 4 weeks; * Poor compliance and unable to complete the course of treatment; * Other reasons the researchers think it is inappropriate to participate in this clinical trial.