Journal of Southern Medical University ›› 2025, Vol. 45 ›› Issue (12): 2718-2725.doi: 10.12122/j.issn.1673-4254.2025.12.19

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Analysis of setup errors and their correlation with clinical factors in image-guided radiotherapy for prostate cancer using different immobilization devices

Xuan GUO1,2(), Yang LIU1, Yan XIONG1, Biaoshui LIU1, Ting SONG2, Yunfei LI1()   

  1. 1.Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, China
    2.School of Biomedical Engineering, Southern Medical University, Guangzhou 510515, China
  • Received:2025-05-13 Online:2025-12-20 Published:2025-12-22
  • Contact: Yunfei LI E-mail:guoxuan@sysucc.org.cn;liyf1@syusucc.org.cn
  • Supported by:
    Supported by National Natural Science Foundation of China(82472117);Youth Program of National Natural Science Foundation of China(82303954)

Abstract:

Objective To quantitatively analyze setup errors of 4 immobilization devices in precision radiotherapy for prostate cancer, their accuracy differences, and the factors affecting their setup precisions. Methods We conducted a retrospective analysis of 240 prostate cancer patients undergoing image-guided radiotherapy at Sun Yat-sen University Cancer Center from May, 2016 to May, 2024. According to the immobilization devices used, the patients were divided into 1.2 m vacuum bag group (n=60), 1.8 m vacuum bag group (n=60), Orfit frame group (n=60), and customized prone board group (n=60). All the patients received pre-treatment cone-beam CT (CBCT) scans, and setup errors in the right-left (RL), superior-inferior (SI), and anterior-posterior (AP) directions were obtained through XVI system grayscale registration. Further subgroup analyses were performed based on patient stratifications by lymph node irradiation status (n=120 each), age (<65 years, n=80; ≥65 years, n=160), and BMI (BMI<24 kg/m², n=120; BMI≥24 kg/m², n=120). Results The setup errors differed significantly among the 4 groups in three-dimensional directions (P<0.05). The customized prone board group showed minimal errors in the RL (0.02±0.25 cm) and SI (0.01±0.32 cm) directions, but demonstrated the largest error in the AP direction (-0.28±0.36 cm). The patients with lymph node irradiation had significantly greater AP directional errors (-0.22±0.36 cm) than those without (-0.01±0.43 cm; P<0.001). BMI showed a negative correlation with SI directional errors (R=-0.45, P<0.001), while age was not significantly correlated with the setup errors (P>0.05). Conclusion The customized prone board demonstrates clinically significant advantages for its high setup accuracies in RL and SI directions in spite of its systematic AP directional errors. The setup accuracy in the SI direction is especially important for patients with lymph node irradiation or low BMI. Our findings provide quantitative evidence for immobilization device selection and individualized optimization of precision radiotherapy for prostate cancer.

Key words: prostate cancer, immobilization devices, setup errors, body mass index