Radiation therapy is also a treatment modality for prostate cancer, including radical radiation therapy, adjuvant radiation therapy and salvage radiation therapy. In the past, the effect of radical radiotherapy and surgery was comparable, but in the past few years, with the continuous progress of surgery and equipment, more and more patients are having radical surgery and the effect is better than radiotherapy. Therefore, radiotherapy is now generally an option for patients who cannot afford surgery. There are two types of radiotherapy for prostate cancer, external radiation (external radiotherapy) and internal particle implantation (internal radiotherapy). External radiotherapy is the use of radiation to irradiate the tumor area to kill the tumor cells, but the radiation may cause damage to the surrounding organs (such as bladder, colorectum, etc.) as well, which was the most common side effect of radiotherapy in the past. With the development of science, the most commonly used technique is called intensity-modulated, conformal radiotherapy, which sets the radiation dose at different locations according to the shape of the tumor, so that the radiation is focused on the tumor lesion area, while the radiation dose at the marginal locations is less. This type of radiotherapy can protect the other organs around the prostate and try to avoid radiotherapy side effects. The percentage of erectile dysfunction and urinary incontinence caused by this method is relatively low, so most patients can still have a sexual life. The radiation source can produce short-range radiation to kill tumor cells in close proximity, increasing the local dose to the prostate and reducing the radiation dose to the rectum and bladder, which is suitable for It is suitable for the treatment of early stage tumors, and can also be used as an adjuvant for the treatment of intermediate and late stage tumors, along with external radiotherapy or endocrine therapy. Since the radioactive particles are implanted into the prostate by puncture, there will inevitably be some damage, such as hematuria, difficulty in urination, and some impact on sexual function, but the incidence is not high. Of course, if the puncture is very close to the vascular nerve bundle, it may still cause sexual dysfunction. It should be added that the distance of tissue penetration of the implanted particles is very short, only a dozen millimeters, so internal radiotherapy has no effect on other family members. The family life of the old man should not be affected by the implantation of radioactive particles, which is unnecessary and will be a great blow to the confidence of the old man to overcome the disease.