Objective To illustrate the basic operational principle of the control software item Part and value ( IPV) of Elekta digital medical linac and specifically explain that the control software monitors and controls the subsystems in a real-time manner by using three types of items and Parts. Methods Firstly, the composition of the control system of Elekta digital medical linac was introduced. Then, the definition and category of the items and Parts of the control software and the basic principle of different types of items were illustrated. Finally, the application of control software items and Parts in real-time monitoring and controlling the operation of subsystems was evaluated by analyzing the motion control of high-power ( HP) phase shifter. Results By analyzing the principle and citing a classical example to specifically illustrate the operational principle and application of control software IPVs, the users, especially the maintenance personnel, could master relevant theoretical knowledge, rapidly and accurately find the operational parameters during daily use and maintenance, besides analyze and resolve the problems based on the control principle of relevant subsystem. Conclusion Users, especially the maintenance personnel who master the working principle of these subprojects and their project sub-items can quickly and accurately check, calibrate the operating parameters via the control software, resolve equipment failure and avoid accidents caused by inappropriate operation in the daily use or maintenance.

Objective    To investigate the short-term therapeutic effect of neoadjuvant immunotherapy combined with chemotherapy in the locally advanced esophageal squamous cell carcinoma. Methods    The clinical data of patients with esophageal squamous cell carcinoma treated with neoadjuvant treatment in Gaozhou People's Hospital from August 2019 to October 2020 were retrospectively analyzed. According to the different treatments, the patients were divided into two groups: a neoadjuvant immunotherapy combined with chemotherapy group (NIC group) and a neoadjuvant chemoradiotherapy group (NC group). The baseline data, incidence of adverse events during treatment, perioperative indicators, postoperative pathological remission rate and incidence of postoperative complications were compared between the two groups. Results    Totally 33 patients were enrolled, including 15 males and 18 females, with an average age of 62.37±7.99 years. There were 17 patients in the NIC group and 16 patients in the NC group. In the NIC group, the carcinoma was mainly located in the middle and lower esophagus, with 5 paitents in stage Ⅱ, 9 patients in stage Ⅲ, and 3 patients in stage Ⅳa. In the NC group, the carcinoma was mainly located in the upper-middle esophagus, with 1 patient in stage Ⅱ and 15 patients in stage Ⅲ. During the neoadjuvant treatment, there was no significant difference in the occurrence of bone marrow suppression or gastrointestinal reactions between the two groups (P>0.05). There were 4 immune-related rashes in the NIC group and 1 esophageal perforation in the NC group. Fourteen (82.35%) patients in the NIC group and 12 (75.00%) patients in the NC group completed the operation on schedule. The postoperative ICU stay time and chest tube indwelling time in the NIC group were shorter than those in the NC group (P<0.05). There were 5 patients of complete remission in the NIC group, and 6 patients in the NC group. There was no significant difference in the pathological regression grade or residual tumor cells between the two groups (P>0.05). There was no significant difference in the incidence of anastomotic fistula, thoracic gastric fistula, bronchial mediastinal fistula, abdominal distension, pulmonary infection, stroke, or hoarseness during the perioperative period between the two groups of patients who completed the operation (P>0.05). In the NC group, 2 patients died during the perioperative period because of thoracic gastric fistula complicated by severe infection. Conclusion    Neoadjuvant immunotherapy combined with chemotherapy dose not significantly increase the occurrence of adverse events and shows a good rate of pathological remission, which indicates that the neoadjuvant immunotherapy combined with chemotherapy is a safe, feasible and potential new treatment model.