Using overlap volume histogram and IMRT plan data to guide and automate VMAT planning: a head-and-neck case study

Area of Science:

• Radiation Oncology
• Medical Physics
• Cancer Treatment

Background:

• Intensity-modulated radiation therapy (IMRT) is a standard for head-and-neck cancer treatment.
• Volumetric-modulated arc therapy (VMAT) offers potential advantages in treatment delivery efficiency.
• Automating VMAT planning can reduce planning time and improve consistency.

Purpose of the Study:

• To evaluate an automated VMAT planning system driven by overlap volume histogram (OVH) data from IMRT plans.
• To assess the dosimetric quality of automated VMAT plans compared to traditional IMRT plans for head-and-neck cancers.

Main Methods:

• An in-house developed OVH-driven automated planning application was integrated into Pinnacle(3) SmartArc.
• The application utilized a database of prior clinical head-and-neck IMRT plans.
• Double-arc VMAT plans were generated for 12 head-and-neck cancer patients (oropharynx, nasopharynx, larynx) and compared to their clinical IMRT plans.

Main Results:

• Automated VMAT plan generation required an average of two optimization rounds, compared to 43 for clinical IMRT plans.
• VMAT plans demonstrated statistically superior sparing of organs at risk (cord+4 mm, brainstem, brachial plexus, larynx, inner ear) (p < 0.01).
• Minor degradation in low-dose planning target volume (PTV) coverage was observed in VMAT plans (V(95) reduced by 0.3%, p = 0.25).

Conclusions:

• IMRT data-driven automated VMAT planning is a viable method for generating head-and-neck cancer treatment plans.
• This approach yields dosimetric quality comparable to IMRT while significantly reducing planning time.
• Automated VMAT planning shows promise for improving efficiency and organ-at-risk sparing in radiation oncology.