Application of statistical process control for quality assurance in radiotherapy planning of nasopharyngeal carcinoma

To evaluate whether a statistical process control (SPC) method can improve the safety and stability of radiotherapy planning for patients with nasopharyngeal carcinoma. A total of 200 patients were retrospectively enrolled and divided into 2 sequential phases. The first phase (100 patients) was used to establish baseline statistical parameters including centerlines and control limits. The second phase (100 patients) used these parameters to guide plan optimization. Dose indicators of organs at risk, target coverage, process stability, and process capability index were analyzed and compared between the 2 phases. After applying SPC, radiation doses to the larynx and parotid glands were significantly reduced, while target volume coverage was adequately maintained. All plans remained within stable statistical control limits, and process capability indices were improved, indicating enhanced process stability and reliability. SPC provides an effective, data-driven, and easy-to-implement tool for improving nasopharyngeal carcinoma radiotherapy planning. It reduces unnecessary radiation exposure to normal tissues, enhances process stability, and promotes consistent high-quality treatment. This method is clinically feasible and suitable for widespread application in routine radiotherapy quality assurance.