I125 Seed Implantation vs Stereotactic Radiotherapy for Pancreatic Cancer

1. Radiation: Stereotactic Radiotherapy 1.1 Equipment: Accuray VSI Cyberknife stereotactic radiotherapy platform, simulated positioning CT machine, MR, positron emission computed tomography PET-CT, vacuum pad. 1.2 Radiotherapy localization: CT, MRI and PETCT were used to simulate localization. 1.3 Relevant Definitions of Tumor Targets CT, MRI, PET-CT fusion, combined with MRI location and PET-CT location image for sketching. To delineate target areas and organs at risk. GTV: Combining localization and fusion images to delineate the tumors seen PTV = GTV + 0-10mm Dangerous organs: The stomach, duodenum, jejunum, ileum, colon, spinal cord and esophagus were delineated on the base sequence of CT plain scan. The target area should be approved by at least one physician in charge or by a physician in charge. 1.4 Target volume radiation dose: According to the volume, location, organ function and other factors, the dosage of radiotherapy was determined. The range of BED value of radiotherapy was 80-100 when the distance between the tumor and gastrointestinal tract was more than 5 mm (alpha/beta=10) and 60-80 when the distance between the tumor and gastrointestinal tract was less than 5 mm (alpha/beta=10). 1.5 Normal Tissue Limit: Reference to TG101 Report 2. CT-guided radioactive 125I seeds therapy with 3D printing template for pancreatic cancer 2.1 Preoperative planning 2.2 Design and fabrication of 3D-PNCT 2.3 125I seeds implantation: 3D-PNCT was placed on the surface of the patient's treatment area, and positioned with the help of the patient's outline features, laser lines, body surface positioning lines and template alignment reference lines. The location of the template and the tumor is well repeated. If there are errors, the template should be adjusted in time. The insertion needle was percutaneously punctured to a predetermined depth through a template guide hole. During the puncture process, the puncture path was monitored by CT scanning and fine-tuned if necessary to avoid injuring nerves and blood vessels. Seeds implantation and CT scan were performed according to the preoperative plan to understand the distribution of seeds. During the operation, the implant needle should be added or reduced when necessary to ensure that the whole target area is adequately irradiated and the surrounding normal tissues are protected. 2.4 Postoperative dose assessment: CT scan was performed after operation, and the image was transmitted to BTPS for dose verification (Figure 3-4). The dosimetric parameters included tumor volume, D90, mPD, V100, V150 and V200. After these treatments,to evaluate the clinical efficacy of stereotactic radiotherapy and ct-guided 125I seed therapy with 3D printing template in pancreatic cancer;In addition, the local control rate and side effects of ct-guided radioactive 125I particles in the treatment of pancreatic cancer lesions were explored, and the efficacy and safety of different doses of stereotactic radiotherapy were determined.