A Dosimetric Comparison between Spiral Volumetric Modulated Arc Therapy and Volumetric Modulated Arc Therapy In Radiotherapy for Cervical Cancer: Focusing on Ovarian Protection
Abstract
Purpose
To evaluate the planning feasibility of spiral volumetric modulated arc therapy (SVMAT) for preserving ovarian function in cervical cancer radiotherapy. The SVMAT technique, which integrates longitudinal couch movement, combines the efficiency of volumetric modulated arc therapy (VMAT) with the helical irradiation advantage of helical tomography (HT), offering a new technical option for young patients requiring ovarian function preservation.
Methods
This study retrospectively analyzed 15 cervical cancer patients treated between January 2020 and December 2024. For each patient, an Elekta VMAT plan (Group A) and a Neusoft ZhiRui SVMAT plan (Group B) were created. The SVMAT plans were executed using a fractionated couch-shift technique, with the total number of gantry rotations ranging from 6 to 16. All plans were optimized with the goal of delivering a prescription dose of 50 Gy in 25 fractions to 95% of the target volume. Plan quality was assessed by comparing dosimetric parameters, and statistical methods were employed to analyze differences between the groups (with p 0.05). However, the SVMAT plans significantly reduced the mean ovarian dose (Group B: 3.66 ± 0.66 Gy vs. Group A: 5.12 ± 0.41 Gy, p < 0.01) and the maximum ovarian dose (Group B: 5.71 ± 1.18 Gy vs. Group A: 7.62 ± 1.31 Gy, p < 0.01). Advantages were also observed in reducing dosimetric parameters for the bladder, femoral heads, and small intestine.
Conclusion
For cervical cancer radiotherapy, SVMAT can achieve target dose distributions comparable to VMAT while providing superior protection for the ovaries and other pelvic organs at risk.