Treatment plan complexity metrics for predicting IMRT pre-treatment quality assurance results

Area of Science:

• Radiation Oncology
• Medical Physics
• Radiotherapy Planning

Background:

• Intensity-modulated radiation therapy (IMRT) planning necessitates a trade-off between achieving optimal dose conformity and ensuring treatment deliverability.
• Evaluating treatment plan complexity is crucial for predicting successful quality assurance (QA) outcomes.
• Existing complexity metrics may not fully capture the nuances of IMRT plan deliverability.

Purpose of the Study:

• To investigate the efficacy of established and novel treatment complexity metrics in assessing IMRT plan deliverability for prostate cancer.
• To identify metrics that can reliably distinguish between IMRT plans that pass and fail QA tests.
• To introduce and validate a new metric, the 'small aperture score', for predicting treatment plan quality.

Main Methods:

• Analysis of 122 IMRT beams from prostate treatment plans.
• Utilization of Treatment and Dose Assessor software to extract plan data and calculate complexity metrics.
• Comparison of metric values for plans that passed versus failed quality assurance (QA) tests.

Main Results:

• Most investigated metrics showed no significant difference between plans that passed or failed QA.
• Statistically significant variations were observed for the established modulation index and the novel 'small aperture score'.
• The 'small aperture score' demonstrated a strong ability to differentiate deliverable plans from those failing QA, with a low false negative rate.

Conclusions:

• The 'small aperture score' is a promising novel metric for assessing IMRT plan deliverability and predicting QA outcomes.
• This metric can aid in identifying potentially undeliverable IMRT plans, thereby improving treatment quality and patient safety.
• Further validation of the 'small aperture score' in diverse clinical scenarios is warranted.