2016 - Effects of Daytime and Nighttime Radiotherapy on Treatment Accuracy: A Prospective, Self-Controlled, Nonrandomized Study
Presenter(s)
F. Bai1, L. Zhang1, J. Li2, L. Bo3, F. T. Yang4, L. Zixuan5, R. Cai6, R. Wang7, J. Ma7, W. X. Yao4,8, Q. X. Hu9, L. L. Xu10, H. Yang11, L. Wei11, and L. N. Zhao11; 1Department of Radiation Oncology, Xijing Hospital, Fourth Military Medical University, xi'an, Shaanxi, China, 2Department of Radiation Oncology,Xijing Hospital,Air Force Medical University CN, Xi’an, China, 3Department of Radiation Oncology, Xijing Hospital, Fourth Military Medical University. Xi’an, China, Xi'an, Shanxi, China, 4Department of Radiation Oncology, Xijing Hospital, Fourth Military Medical University., xi'an, shaanxi, China, 5Department of Radiation Oncology, Xijing Hospital, Fourth Military Medical University. Xi’an, China, Xi'an, Shaanxi Province, China, 6Department of Radiotherapy, Xijing Hospital, Fourth Military Medical University, Xi'an, Shaanxi, China, 7Department of Radiation Oncology, Xijing Hospital, Fourth Military Medical University., Xi’an, shaanxi, China, 8Department of Radiation Oncology, Xijing Hospital, Fourth Military Medical University, xi'an, shannxi, China, 9Department of Radiation Oncology, Xijing Hospital, Fourth Military Medical University, Xi’an, shaanxi, China, 10Department of Radiation Oncology, Xijing Hospital, Fourth Military Medical University, xi'an, shaanxi, China, 11Department of radiation oncology, Xijing Hospital, the Fourth Military Medical University, Xi'an, China
Purpose/Objective(s): A growing body of research confirms the important role of circadian rhythms in radiation-induced side effects and prognosis. However, its impact on setup accuracy and therapist setup remains poorly understood. Therefore, the purpose of this study is to explore the impact of daytime and nighttime radiotherapy on treatment accuracy.
Materials/Methods: A prospective, self-controlled, nonrandomized study design was used to enroll consecutive rectal cancer patients undergoing radiotherapy between June 2024 and January 2025. Each patient received at least one dose of radiation during the day (before 20:00) and at night (after 20:00), and all patients received the same dose (5× 5 Gy) and the same regimen. CBCT was used to verify the position of all patients before each treatment, and the setup errors in three dimensions (X, Y, Z axis) and rotation angle (RTN) were obtained. The setup errors of patients during daytime and nighttime radiotherapy, the setup errors of same therapist during daytime and nighttime, and the setup errors of different therapists were analyzed statistically.
Results: A total of 379 CBCT scans (165 daytime and 214 nighttime) of 80 patients (45 males and 35 females) with rectal cancer were included in the analysis. The results showed that in the X-direction, the setup error was (1.32±1.08) mm for daytime radiotherapy and (1.33±1.07) mm for nighttime radiotherapy, with a P-value of 0.94; in the Y-direction, the setup error was (2.44±1.40) mm for daytime radiotherapy and (2.53±1.41) mm for nighttime radiotherapy, with a P-value of 0.67; in the Z direction, the setup error was (1.38±0.94) mm for daytime radiotherapy and (1.34±0.69) mm for nighttime radiotherapy, with a P value of 0.677. In addition, in terms of RTN, the setup error of daytime radiotherapy was (0.455±0.355)°, and the setup error of nighttime radiotherapy was (0.536±0.328)°, with a P value of 0.051. Further analysis revealed that there was a statistically significant difference in the setup error in RTN when divided by 22:00 hrs and no statistically significant difference in the other three directions, but the mean values of setup error at night were all greater than that of daytime. The results of therapist setup showed that there was no statistically significant difference between daytime and nighttime setup errors for the same therapists; there was a statistically significant difference between different therapists, which was reflected in the Y direction (F=2.677, p=0.005).
Conclusion: This prospective study is the first to demonstrate that treatment accuracy is unaffected by daytime and nighttime radiotherapy. Setup accuracy was consistent for the same therapist during both daytime and nighttime, but varied between different therapists. In clinical practice, considering factors such as side effects, daytime radiotherapy is recommended when feasible.