Particle Knife (125I Seed Implants) applies to a variety of primary and metastatic tumors.125I seeds implant are an energy radionuclide which can give off continuous, short-range γ-ray to kill tumor cells. It can achieve the same internal radiation effects on tumor as surgery does. Hence, it is called seeds knife. Iodine implants are 0.8 mm in thickness, about 0.4 cm in length.