Advanced equipment should be selected for postoperative radiotherapy. Harbin 2 1 1 Hospital Oncology Department has gamma knife equipment imported from abroad, which has a good effect in treating head and body tumors and postoperative tumors. Gamma knife adopts the geometric focusing method of gamma rays, and focuses the planned dose of gamma rays on the pre-selected target in the body through accurate stereotactic, thus fatally destroying the tissues in the point at one time and achieving the effect of surgical resection or destruction. The normal tissue around the focus is out of focus and only irradiated by a single beam of gamma rays, so the energy is very low and it is not damaged. Just like focusing sunlight with a magnifying glass, the focused heat can ignite an object, while the sunlight outside the focus is safe. Using gamma rays instead of scalpels, the boundary between the therapeutic irradiation range and normal tissues is very obvious, and the edge is like a knife, so people call it "gamma knife" vividly.