ABSTRACT
Objective:To analyze the duration of each phase of Unity MR-linac in clinical application, aiming to provide reference for clinical optimization of the process time.Methods:Clinical data of 55 patients treated with Unity MR-linac were retrospectively analyzed. All patients were divided into the adapt to position (ATP) and adapt to shape (ATS) groups according to the planning method. The duration of each phase in the treatment process, the name and the time of each sequence, the number of beams, segments and total monitor units (MUs) were recorded and compared between two groups. In addition, the set-up time was counted according to different treatment sites. The time of each sequence and set-up time were expressed as the median M (Q 1, Q 3), and the number of beams, segments and total MUs of each plan were described as the mean±SD. Results:42 patients underwent ATP with a total of 305 treatment sessions: setup time was 3(2, 5) min, MR scanning time was 5(4, 7) min, registration time was 3(3, 4) min, adaptive planning time was 8(4, 12) min, beam on time was 8(6, 11) min, and the total time was 30(25, 36) min. 13 patients received ATS with a total of 65 treatment sessions: setup time was 2(2, 3) min, MR scanning time was 7(5, 8) min, registration time was 4(3, 5) min, time of delineation of target and organs at risk was 12(9, 16) min, adaptive planning time was 11(10, 14) min, beam on time was 10(9, 11) min and the total time was 55(49, 61) min. The set-up time according to treatment sites was 4(2, 4) min in the head and neck, 2(2, 4) min in the chest, and 3(2, 5) min in the abdomen. The number of fields, segments and total MUs during ATP were 8.1±1.7, 49.9±31.2, 846.75±363.44 in the head and neck, 8.0±2.0, 60.7±13.3, 790.21±279.00 in the chest, and 9.7±2.0, 81.2±22.3, 2007.32±1053.81 in the abdomen, respectively. The number of fields, segments and total MUs during ATS in head and neck of one case were 13, 39, 993.07, and 9.5±1.5, 65.5±6.3, 2763.26±835.41 in the abdomen.Conclusions:MR-guided radiotherapy yields huge potential in clinical application. However, there is still much room for the improvement of shortening the process duration.