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Updated: May 6, 2026
Stereotactic Radiosurgery for Gynecologic Cancer
Published on: April 17, 2012
The impact of setup errors on dose distribution in cervical cancer radiotherapy and the margin from CTV to PTV
Zhenghuan Li1, Yuan Cheng2, Jie Dong3
1Department of Radiation Oncology, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, 510630, China. 1347503990@qq.com.
Purpose:
This study calculates the needed margin from clinical target volume (CTV) to planning target volume (PTV) in IMRT for cervical cancer. It also assesses the impact of setup errors on target and organ at risk (OAR) dose distribution.
Methods:
We retrospectively analyzed 50 cervical cancer patients who underwent IMRT, with 210 CBCT scans. We calculated the CTV-to-PTV margin and simulated setup errors in the TPS to reassess dose distribution impacts on targets and OAR.
Results:
Setup errors in X(anterior-posterior,AP), Y(cranial-caudal,CC), and Z(left-right,LR) directions were (1.4 ± 1.0) mm, (2.3 ± 1.5) mm, and (1.9 ± 1.2) mm, respectively, leading to CTV-to-PTV margins of 4.4 mm, 6.4 mm, and 5.8 mm. X-axis errors did not significantly affect target dosimetry (P > 0.05), but Y and Z errors did (P < 0.05). X-axis errors impacted the small intestine and rectum (P < 0.05), Y-axis errors mainly affected the colon (P < 0.05), and Z-axis errors affected the colon, small intestine, and rectum (P < 0.05).
Conclusion:
Our study underscores the need to account for setup errors in radiotherapy for cervical cancer. Customizing the CTV-to-PTV margin based on institutional error data is key to maintaining target dose coverage and optimizing treatment outcomes.
