Quantitative assessment of helical tomotherapy plans complexity

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Planning

Background:

• Treatment plan complexity in radiotherapy can reduce efficiency and increase uncertainty in dose delivery.
• Quantitative tools for assessing helical tomotherapy (HT) plan complexity are currently limited.
• Complexity can lead to increased susceptibility to anatomical changes and setup errors.

Purpose of the Study:

• To develop and investigate the effectiveness of new metrics for characterizing helical tomotherapy (HT) plan complexity.
• To address the limitations in current quantitative assessment tools for HT plans.
• To improve the understanding of factors contributing to radiotherapy plan complexity.

Main Methods:

• Evaluated 464 HT plans delivered on a Radixact platform.
• Developed new metrics for beam geometry, leaf opening time (LOT) variability, and spatial/temporal modulation.
• Utilized the TCoMX software library to extract 65 complexity metrics, including 36 newly developed ones, and correlated them with patient-specific quality assurance (PSQA) results.

Main Results:

• Identified intrinsic links between LOT distribution and the geometrical complexity of multi-leaf collimator (MLC) openings.
• Newly developed metrics demonstrated correlations with PSQA results comparable to existing metrics.
• Metrics quantifying MLC opening geometrical complexity showed the strongest correlation with PSQA results, with significant findings for six out of seven plan groups.

Conclusions:

• The proposed new metrics provide a more comprehensive characterization of HT plan complexity.
• The developed metrics are effective in evaluating treatment plan complexity and its impact on quality assurance.
• A software library for automatic extraction of these metrics is available.