Radiotherapy is the abbreviation of radiation therapy, which is mainly used for the treatment of tumors. It is very important for patients to take care of their diet during radiotherapy. The doctor will give a more detailed introduction to the patient at the beginning of the treatment. Generally speaking, we should pay attention to the following aspects. (1) At the beginning of radiotherapy, we should pay attention to adjust the diet structure. It should be light and tasty, easy to digest and nutritious, to maximize the use of appetite, to eat more when the appetite is good, when the appetite is reduced or anorexia, delicious taste plus spiritual encouragement often receive results. (2) The patient’s diet should be arranged according to the principles of high calorie, high protein and high vitamin; the diet should be diversified as much as possible, and efforts should be made in the pattern of food and the color, aroma and taste of dishes. Especially for patients receiving head treatment, they often have “mouth blindness” and lose the sense of taste in the tongue. Drink a small amount of wine, coffee or tea, for some patients also have the effect of appetite. (3) To have small amount of meals and drink more boiled water to facilitate the discharge of tumor metabolism toxins accumulated in the body as soon as possible. For those who eat less, they can arrange their diet according to five or six meals a day. For those who have severe pain in eating, they can take appropriate amount of painkillers or numbing medicine before meal. Patients with nausea and vomiting, appropriate vitamin B6, or methotrexate and other drugs taken orally; or in cooking into 1 to 2 sand nuts, can stop vomiting. (4) too sweet, greasy, hot, spicy, smelly, too much fiber, hard and difficult to chew food, often aggravate nausea, strive to eat as little as possible or best to avoid not to eat. Fibrous cereal porridge, bran noodles and too cold and too hot food, easy to accelerate intestinal peristalsis caused by diarrhea, daily life of alfalfa, leek, bamboo shoots, yams, bananas, etc. should also be eaten sparingly. (5) radiation therapy patients often cause “fluid deficiency” and “internal heat”, so it is best not to eat mutton and dog meat and other foods that are hot, vegetables can be selected from the young leaves, the amount should not be too much, fried food is easy to make people “on fire “, should not eat more. (6) to pay attention to the processing of food. Radiotherapy is prone to severe dry mouth, dry throat, oral erosion, resulting in chewing difficulties and painful swallowing. Therefore, it is best to process food into a state that is easy to chew and swallow, such as processing meat and vegetables into meat sauce and vegetable puree, and with tasty and nutritious soups to help patients swallow. The temperature of the meal should be cool. Some patients also find it difficult to eat vegetables and fruits, so they may want to drink juice and vegetable juice instead. (7) For easily digestible food, such as rice porridge, boiled noodles, soft rice, steamed egg custard, soybean products, nourishing and cooling wolfberry, lily, mung beans, peanuts, red dates, adzuki beans, etc., can often be taken. (8) irradiation treatment will affect the secretion function of salivary glands, not only to reduce saliva secretion, but also become thick, thus causing dryness in the mouth. And sweet food can reduce saliva secretion, making the mouth more dry, therefore, to eat less sweet food. General acidic food can increase salivary secretion, and can often eat hawthorn tablets; such as the use of Chinese medicine dendrobium (fresh) decoction for tea, it can moisten and generate fluid, and is quite effective in easing dry mouth. The decoction or tea of American ginseng is even better. (9) To observe the weight change of the patient during radiotherapy, which is the easiest way to measure the adequacy of nutritional intake. If the patient loses more than 5% of body weight, he/she should report to the doctor to check the reason, so as to reformulate the nutrition plan, otherwise it will be difficult for the patient to adhere to the anti-cancer treatment. (10) After the completion of radiotherapy, the patient’s “mouth blindness” will last for one month or more before the appetite is restored, and the dry mouth may persist for a longer period of time. Therefore, it is necessary to eat more soup and water. Patients should also avoid eating too hot food and cold drinks to avoid damage to the teeth. Usually rinse mouth with light salt water or 3% boric acid solution to prevent oral inflammation and ulcers. After radiotherapy, teeth are very easy to be decayed, so make sure to wipe your teeth with hydrogen peroxide frequently.