The planning and implementation of modern radiotherapy is a complex and complete process with multiple links and steps, each link and step is connected like a series circuit, and any error will lead to treatment failure. (i) Clinical assessment: Before implementing radiation therapy, the patient’s medical history, physical examination, imaging data, general condition, comorbidities should be understood in detail, the patient’s tolerance to radiation therapy should be assessed, and the purpose of radiation therapy, i.e., radical radiotherapy or palliative radiotherapy, should be determined. (2) Position fixation: To ensure accurate implementation of radiation therapy, patients should try to adopt a comfortable and reproducible position that can meet the treatment needs, and use some position fixation devices such as warm plastic mask, vacuum pad, body frame, etc. as far as possible. Repeatability of position is a very critical aspect of radiation therapy. (iii) X-ray/CT positioning: roughly determine the center of the irradiation field under the simulated positioning X-ray machine, mark the laser line, and perform CT scan in the same position. Or scan directly under the CT analog positioning machine, determine the center of the irradiation field, and mark the laser line. (iv) Outlining the target area and endangered organs: This is the most complicated and critical step of radiation therapy. The physician outlines the patient contour, treatment target area and normal tissue layer by layer on the positioning CT. (v) Radiation treatment planning: The physician gives the prescribed dose for each target area of the tumor and the dose limit for normal tissues, and then the physicist calculates the optimal beam intensity distribution for each field with the aid of computer, so that the actual dose distribution formed in the body is close to the physician’s prescribed dose. (vi) Program evaluation: To assess whether the tumor irradiated dose meets the clinical requirements and whether the normal tissue dose exceeds the tolerated dose. (vii) Position verification: During the implementation of radiation treatment plan, the patient’s body position may be deviated, in order to ensure the accuracy of treatment, position verification must be performed in the first time of radiotherapy. The method of position verification includes taking EPID or CT images, then positioning X-rays or CT images to match and measure the error between the two, and to find out the cause of large errors and correct them in time. (H) Dose verification: Dose verification is to confirm whether the actual dose of the patient is the same as the planned dose given, usually using the model instead of the body measurement, the measurement mainly includes absolute dose measurement and relative dose measurement, such as the absolute dose measurement of the point, the relative dose measurement of the cross-section, and then compared with the plan. Radiation therapy course Radiation therapy is usually given once a day, 5 days a week, with Saturdays and Sundays off to facilitate the recovery of normal tissue cells. The time required for the whole course of radiotherapy depends on various factors such as the type, location and extent of the tumor, the purpose of treatment, and the patient’s physical condition, and generally takes 5-7 weeks.