When talking about radiotherapy, it may immediately flash in people’s mind: it is a tool used to treat malignant tumors. According to statistics, 80% of malignant tumors need to undergo radiotherapy, and 18% of them can be cured by radiotherapy. However, because of this, the potential clinical application value of radiation therapy for benign diseases has not yet attracted sufficient attention from clinical practitioners. Foreign scholars have done a lot of basic and clinical research work in this area and concluded that the efficiency of radiation therapy for certain benign diseases is 50%-90%. Especially for some benign lesions occurring in important organs, anatomical locations difficult to reach by surgery, traumatic changes that may damage the surrounding important organs or certain cases that are prone to recurrence after surgery and drug treatment, radiotherapy can give full play to its advantages. In the past 30 years, due to the improvement of radiation therapy technology and the in-depth research on adverse effects, abundant experience in preventing adverse effects and reducing cancer-causing risk factors has been accumulated, thus making radiation therapy for benign diseases progress rapidly. Especially in Europe, radiation therapy for benign diseases has become a trend. Within the scope of ophthalmology, otorhinolaryngology, the main benign diseases that radiotherapists deal with clinically and with more definite results are: hyperthyroidism, choroidal hemangioma, inflammatory pseudotumor, optic nerve sheath tumor, nasopharyngeal fibrovascular tumor, jugular vein bullae, keloid tumor, etc. The following are examples of feasible radiotherapy clinical conditions in ophthalmology and otorhinolaryngology in terms of clinical manifestations, radiotherapy dose, radiotherapy effect and side effects. Ophthalmology: Graves’ ophthalmopathy: an autoimmune disease characterized by infiltrative lesions in the soft tissues behind the eye and around the orbit, often accompanied by infiltrative proptosis. Common clinical manifestations include photophobia, tearing, foreign body sensation, eye swelling, and incomplete eyelid closure. As the disease progresses, corneal damage, ocular motility disorders, orbital pain and even vision loss and visual field defects may occur. Inflammatory pseudotumor: Inflammatory pseudotumor of the orbit is a focal lesion that originates in the orbit with fibrous connective tissue hyperplasia with massive inflammatory cell infiltration. Clinical manifestations: eyelid swelling, conjunctival congestion, protrusion and displacement of the eyeball, orbital pain, impaired eye movement and palpable masses at the orbital rim, decreased visual acuity and even edema or atrophy of the optic papilla. Choroidal hemangioma: Choroidal hemangiomas, choroidal hemangiomas, are benign, vascular, misshapen lesions. However, leakage caused by the tumor can lead to complications such as exudative retinal detachment and secondary glaucoma, which can cause significant vision loss or even loss of vision in patients. Otolaryngology: nasopharyngeal fibrovascular disease: also known as “male, adolescent, hemorrhagic, nasopharyngeal hemangioma”, clinical manifestations: repeated nasal and oral hemorrhage, patients often have varying degrees of anemia, can also cause nasal, olfactory hyposmia, tinnitus, such as invasion of adjacent organs cause eye protrusion, vision loss, cheek bulge, intracranial compression of nerves and other corresponding symptoms. The bleeding during surgery of nasopharyngeal fibrovascular tumor is ferocious and can be as much as 2500 to 3000 ml. keloid: keloid is a benign disease, its occurrence may be related to the body type, and it needs to be treated because of its itchy and painful symptoms and its impact on aesthetics. Principles, timing selection and dosage of radiation therapy The current treatment of Graves’ ophthalmopathy and inflammatory pseudotumor is generally based on: glucocorticoids, immunosuppression, depigmentation method, surgical ocular decompression, but all these methods have their own limitations, such as long-term use of hormones and immunosuppressants can cause more serious side effects of systemic treatment and damage to other organs, secondary hypertension, diabetes, stress ulcers, electrolyte disorders, liver and kidney damage, osteoporosis, pathological fractures, mental disorders, dryness and insomnia, hyperphagia and irritability, etc., and the disease tends to recur after stopping the medication. Surgical decompression is also temporary treatment with the infiltration of inflammatory cells, causing single and multiple ocular muscle hypertrophy will proptosis aggravated. Clinical studies have shown that retrobulbar radiotherapy is a more effective treatment. Especially for patients with obvious signs of edema and active inflammatory proptosis, better results can be obtained. For choroidal hemangiomas with exudative retinal detachment, laser photocoagulation, transpupillary thermotherapy, photodynamic therapy (PDT) and radiotherapy are mostly used for treatment. In another 20% of patients, glucocorticoid therapy is ineffective or recurs after discontinuation, and radiation therapy can be considered for such patients. For Graves’ disease, the irradiation dose is mostly 20-30 Gy. Studies have shown that activated retrobulbar T lymphocytes can secrete various cellular agonists. The postbulbar irradiation of Graves’ ophthalmopathy mainly kills the lymphocytes in the extraocular muscle tissue. The dose of radiotherapy for orbital inflammatory pseudotumor is 20-36 Gy. Excessive dose of radiotherapy does not increase the efficacy, but rather greatly increases the incidence of complications. Skin naïve fibroblasts, keratinized tissues and other proliferative stages are sensitive to radiation, so radiation therapy has an anti-proliferative effect on scar tissue, while radiation inhibits postoperative inflammatory cells, immune cell reactions and their induced fibroblast proliferation, and the radiosensitive target cells are monocytes and macrophages that can induce fibroblast proliferation. The endothelial cells of hemangioma are more sensitive to X-rays, and after radiotherapy, the cells first become swollen and then gradually atrophy, thus achieving the effect of shrinking the tumor. The dose of radiotherapy for choroidal hemangioma can be adjusted appropriately according to the volume of tumor, radiotherapy: 15-30Gy, not recommended to exceed 40Gy. Depending on the extent of the lesion, 4-10MV X-rays can be selected and the radiation treatment plan can be 30-45Gy/5 weeks. Preoperative radiotherapy at 10-20 Gy with 2 weeks of rest followed by inpatient surgery is also available. Recurrence after repeated surgery and invasion of the cavernous sinus area at the base of the skull, pterygopalatine fossa, and orbit are not suitable for reoperation, and the dose of radiotherapy can be up to 45 Gy. Effectiveness of radiation therapy Clinical studies have proven that postorbital bulb radiotherapy for Grave’s eye disease is a more effective treatment. Especially in patients with obvious signs of edema and active inflammatory proptosis, better results can be obtained. In orbital inflammatory pseudotumors, the rate of complete regression after low-dose radiotherapy to the orbit is as high as 66%-100%. This is especially true for patients with significant inflammatory manifestations and mild fibrosis, with poorer results in patients with more severe fibrosis, younger patients with vasculitis, and patients with long duration of disease. Approximately 67.4% of patients with inflammatory pseudotumors of the orbit treated with radiation therapy have complete resolution of symptoms within 2 weeks to 1 year after treatment, with review imaging suggesting regression of the mass. The average size reduction of choroidal hemangiomas after radiation therapy was about 45%, and many cases of exudative retinal detachment were able to reset the retina due to absorption of exudate, and no re-retinal detachment occurred at follow-up. The control rate of nasopharyngeal fibrovascular radiotherapy tumors can reach more than 80%. The lesions shrink very slowly after radiation therapy, and the residual small lesions can be delayed for several years, so patients can be followed closely without treatment if they are asymptomatic. In the few cases where treatment fails, a second course of radiation therapy or surgery can be used. The recurrence rate of surgical scar removal alone can reach 50%-80%, and the recurrence rate of postoperative pressure bandaging, hormone injection, and laser treatment still reaches more than 50%. Postoperative radiotherapy is a common method to inhibit scar proliferation, with an efficiency of 70%-93%, and the best results occur in the ear. Radiation therapy damage In radiation therapy, radiation also has certain effects on the normal tissues of the body, causing local or systemic radiation reactions and damage, such as causing mucosal damage, bone marrow suppression, white blood cell reduction, etc. Loss of appetite, difficulty in swallowing, nausea and vomiting, diarrhea, and other gastrointestinal symptoms may occur. However, most of the above systemic reactions are transient and the organism is adaptive. The irradiation dose for benign lesions in ophthalmology, otorhinolaryngology is mostly 20-30Gy, and some patients only show transient and fully recoverable slight facial skin redness and itchiness as after sunburn, and basically no complications such as corneal, retinopathy or optic neuropathy associated with radiotherapy. What’s more, there will be no serious radiation damage to the optic apparatus, optic nerve and key organs around the eye. However, radiotherapy for systemic inflammatory diseases and benign conditions in children must be approached with caution. Late complications of ocular radiotherapy are mainly dry eyes due to hypersecretion of the lacrimal gland after irradiation and vision loss due to crystalline radioactive cataracts, and in some patients, eyelash thinning due to eyelash loss. But basically, these complications can be overcome and subside.