Influence of pre-radiotherapy ultrasonic monitoring of bladder filling levels on setup errors in cervical cancer patients
10.3760/cma.j.cn112271-20240111-00012
- VernacularTitle:放疗前超声监测膀胱充盈度对宫颈癌患者摆位误差的影响
- Author:
Jiangyan LUO
1
;
Haizhen YUE
;
Jiacheng LIU
;
Yichen PU
;
Zihong LU
;
Jianqi HU
;
Hao WU
Author Information
1. 北京大学医学部医学技术研究院，北京 100191
- Publication Type:Journal Article
- Keywords:
Cervical cancer;
Setup error;
Ultrasound;
Bladder filling level;
Margin of planning target volume (MPTV)
- From:
Chinese Journal of Radiological Medicine and Protection
2025;45(4):290-295
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To investigate the influence of ultrasonic monitoring of bladder filling levels on setup errors before fractionated radiotherapy for cervical cancer patients through a comparative analysis, and its effectiveness in improving clinical target volume (CTV) margins.Methods:A retrospective study was conducted on 1 284 error data of setup via cone beam CT (CBCT) and 6D setup error correction system from 172 cervical cancer patients treated in the Radiotherapy Department of Peking University Cancer Hospital from January 2019 to October 2023. These patients were classified into two groups: 87 (659 times of setup) with ultrasonic monitoring of bladder filling levels and 85 (625 times of setup) without ultrasonic monitoring. The setup errors, error distributions, and numbers of abnormal setups between the two groups were compared in the lateral (Lat), longitudinal (Lng), vertical (Vrt), pitch (Pitch), roll (Roll), and rotational (Rtn) dimensions. Moreover, the CTV to planning target volume(PTV) margin values in the three-dimensional direction were calculated for both groups to assess the clinical value of ultrasonic monitoring of bladder filling levels before fractionated radiotherapy.Results:Compared to the group without ultrasonic monitoring, the group with ultrasonic monitoring exhibited lower median values of setup errors in all six-dimensional directions and smaller upper and lower interquartile ranges ( Z = -10.86 to -6.34, P<0.05). The group with ultrasonic monitoring manifested more concentrated setup errors in various directions and statistically significantly reduced numbers of abnormal setups ( χ2=15.33, P<0.05). Moreover, CTV-PTV margins of the group with ultrasonic monitoring displayed reduced CTV-PTV margin values by 0.55, 1.52, and 1.26 mm in the Vrt, Lng, and Lat directions, respectively. Conclusions:Pre-radiotherapy ultrasonic monitoring of bladder filling levels in cervical cancer patients can significantly improve the repeatability of setup, thus notably reducing the incidence of abnormal setups. Theoretically, it can narrow the range from the CTV to the PTV, thereby minimizing radiation exposure to healthy tissues and ultimately enhancing radiotherapy precision for cervical cancer and reducing radiation damage.
