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Anatomy-based parameter selection and efficiency-quality balance in Radixact helical tomotherapy
Longgang Gui1,2, Yin Poo1
1School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, People's Republic of China.
Physics in Medicine and Biology
|June 8, 2026
Summary
Optimizing Radixact helical tomotherapy parameters like jaw width and pitch is crucial for treatment planning. Individualizing these settings based on patient anatomy improves both dose distribution quality and delivery efficiency.
Area of Science:
- Medical Physics
- Radiation Oncology
- Radiotherapy Technology
Background:
- Helical tomotherapy, specifically the Radixact system, offers advanced treatment capabilities.
- Optimizing treatment planning parameters is essential for maximizing therapeutic outcomes while minimizing toxicity.
- Understanding the interplay between physical parameters and anatomical characteristics is key for personalized radiotherapy.
Purpose of the Study:
- To investigate the impact of jaw width, pitch, and modulation factor (MF) on dose distribution and delivery efficiency in Radixact helical tomotherapy.
- To evaluate these effects across diverse patient anatomies, categorized by target volume, shape complexity, and OAR geometry.
- To develop a composite efficiency-quality score (EQS) for treatment plan evaluation.
Main Methods:
- Eighty patients were stratified into four groups based on anatomical characteristics.
- Jaw width (1.0/2.5/5.0 cm), pitch (0.172-0.430), and MF (1.2-4.2) were systematically varied and optimized.
- A composite efficiency-quality score (EQS) was developed to assess treatment plans comprehensively.
Main Results:
- Dynamic jaw mode demonstrated effective longitudinal penumbra control, with 2.5 cm and 5.0 cm settings performing comparably to 1.0 cm static mode.
- The 5.0 cm dynamic jaw mode significantly reduced beam-on time by 43.6% in large-volume targets (Group D) without compromising plan quality.
- Optimal pitch settings were critical for complex targets (Group B), while excessive MF values (4.0) negatively impacted plan quality (gamma pass rate <90% in Group A).
Conclusions:
- Radixact physical parameters require individualization tailored to specific target anatomy for optimal radiotherapy.
- The proposed EQS method offers an anatomy-based approach to optimize treatment planning.
- This strategy aims to effectively balance the competing demands of delivery efficiency and plan quality in helical tomotherapy.
