Total body radiotherapy (TBI) is an important tool in the pretreatment of allogeneic bone marrow transplantation (BMT). It is used to treat leukemia, malignant lymphoma, malignant solid tumors, immune diseases, and genetic disorders. Systemic radiotherapy has three objectives: to produce immunosuppression (killing of white blood cells) in the organism, able to accept bone marrow grafts from donors; to eliminate malignant tumor cells (leukemia, malignant lymphoma and certain solid tumor cells); and to eliminate cell growth in genetic diseases, such as Fanconi’s anemia, severe thalassemia). Fractional total body radiation therapy (Fractional TBI; FTBI) is currently the main method in pretreatment protocols for hematologic malignancies undergoing allogeneic bone marrow transplantation (BMT), and it is not widely used in China. Due to the long treatment time and the need for multiple repetitive poses of fractional total body radiation therapy, the physical requirements of patients and the control of treatment quality are very demanding. The purpose of this study is to observe the early and mid-term toxicity reactions of patients in patients receiving fractionated whole-body radiation therapy and their survival after treatment. Systemic radiotherapy as a systemic drug has many theoretical advantages compared with chemotherapy drugs: 1. there is no shelter for tumor cells, such as testes; 2. the radiation dose is uniformly distributed and independent of the blood supply system; 3. there is no cross-resistance with other chemotherapy drugs; 4. there is no need for detoxification and excretion, so the impairment of body function does not change the radiation dose; 5. the radiation dose to the whole body The distribution can be adjusted according to the need, sensitive normal organs can be given lead-blocking protection, and the recurrence-prone area is given additional dose treatment. The use of a TBI-containing regimen or a chemotherapy regimen containing Bu as a pretreatment regimen for allogeneic bone marrow transplantation has been controversial in clinical practice, with advantages and disadvantages of both regimens. Retrospective non-randomized data from the International Bone Marrow Transplant Registry (IBMTR) showed that the two regimens were similar in terms of treatment survival. In contrast, clinical data from the Japanese Bone Marrow Transplant Registry showed a significant reduction in leukemia relapse rate and a significant increase in long-term survival in the TBI regimen treatment group. In addition, data from a multicenter randomized meta-analysis showed that the allogeneic bone marrow transplantation group with the TBI regimen as a pretreatment regimen had better disease-free survival and long-term survival than the group treated with the leukemia-containing (Bu) regimen. The FTBI regimen is now commonly used in clinical practice for the following reasons: fractionated irradiation has a relatively high therapeutic gain over single irradiation, which can appropriately increase the total irradiation dose; patients can easily maintain their body position, with small dose errors, and each irradiation is shorter and easier to perform, and can be used as routine treatment in most units; and the clinical response is mild, with few complications, and easily accepted by patients. Based on the Seattle experience: 25% of boys who survived more than 5 months after bone marrow transplantation in leukemia patients developed testicular recurrence. the MSKCC cancer center added 4 Gy of localized electron ray irradiation to the testes when giving TBI to leukemia patients after discovering the high rate of testicular recurrence in leukemia patients. If the testis had not been previously irradiated, a full dose was given at once. If the testes have been irradiated before, the irradiation is given in two sessions over two days; if the testes have been irradiated within one or two months before the TBI, the irradiation can be waived again. With these measures, the rate of testicular recurrence in male patients has decreased significantly. The common acute reactions to TBI are nausea and vomiting, followed by oral mucositis, diarrhea, and mumps. The hyper-segmentation irradiation regimen significantly reduces the above-mentioned acute reactions compared with multiple-segmentation irradiation and single-segmentation regimens. The late toxic reactions of TBI are the most important clinical concern. The types of toxic reactions are mainly related to the treatment protocol, the type and dose of chemotherapy drugs used in the treatment process, the total amount of radiotherapy and the segmentation dose, and the source of the grafts. The most common diseases are: 1. Graft-versus-host disease (GVHD), GVHD is an immune reaction of the donor’s T lymphocytes against the normal tissues of the host, dominated by an immune reaction against the organ, and usually occurs within 100 days of allograft transplantation. Interstitial pneumonia occurs mostly in radiation pneumonia after TBI, with an incidence of no more than 20% in patients not treated with TBI. Two-thirds of radiation pneumonia develops into interstitial pneumonia, and interstitial pneumonia caused by radiation pneumonia usually occurs within 100 days after transplantation, secondary to cytomegalovirus pneumonia (CMV) leading to death. Interstitial pneumonia can occur within one to two years after transplantation. Chronic hepatitis, infectious hepatitis, leukocyte infiltration and potentially lethal lesions of the liver: veno-occlusive disease (VOD), the main cause of VOD is chemotherapy and TBI, and high doses and rates of TBI can easily lead to VOD. Impairment of renal function is also frequently reported after BMT, and common risk factors are Arac combined with cyclophosphamide, TBI, immunosuppressant cyclosporine, anti-mycobacterial drug Itronomycin B. 5, Many endocrine dysfunctions can occur after BMT, such as hypothyroidism, dysplasia, sexual dysfunction and infertility. 6. Through long-term follow-up, it is found that patients will develop second malignant tumors within about ten years after BMT. Some studies have shown that the incidence of second malignant tumors in patients who have received TBI is significantly higher than that in patients treated with chemotherapy alone, but there is also a contrary view that there is no significant difference in the incidence of second malignant tumors between the two. With the rapid development of radiation therapy technology, many new clinical treatments for TBI have emerged, among which the most representative method is 3D image guided tomographic intensity modulated radiation therapy, which may become the standard treatment for TBI in the future. The most representative method is 3D image guided tomographic intensity modulated radiation therapy, which may become the standard treatment for TBI in the future, because the target area of this treatment technique is only the bone marrow and other diseased tissues that need to be irradiated, which can greatly protect normal tissues such as lung tissue, liver and kidney tissue, reduce late complications and improve productivity. Moreover, this treatment technique can be applied within the standard treatment distance, and no split treatment is required to complete the treatment in a single session. However, the relevant treatment parameters and the impact on patient survival are still under clinical studies and experiments.