Purpose: To evaluate automated multicriteria optimization (MCO)-- designed for intensity modulated radiation therapy (IMRT), but invoked with limited segmentation -- to efficiently produce high quality 3D conformal treatment (3D-CRT) plans.

Methods: Ten patients previously planned with 3D-CRT were replanned with a low-segment inverse multicriteria optimized technique. The MCO-3D plans used the same number of beams, beam geometry and machine parameters of the corresponding 3D plans, but were limited to an energy of 6 MV. The MCO-3D plans were optimized using a fluence-based MCO IMRT algorithm and then, after MCO navigation, segmented with a low number of segments. The 3D and MCO-3D plans were compared by evaluating mean doses to individual organs at risk (OARs), mean doses to combined OARs, homogeneity indexes (HI), monitor units (MUs), physician preference, and qualitative assessments of planning time and plan customizability.

Results: The MCO-3D plans significantly reduced the OAR mean doses and monitor units while maintaining good coverage and homogeneity of target volumes. MCO allows for more streamlined plan customization. All MCO-3D plans were preferred by physicians over their corresponding 3D plans.

Conclusion: High quality 3D plans can be produced using IMRT optimization technology, resulting in automated field-in-field type plans with good monitor unit efficiency. Adopting this technology in a clinic could streamline treatment plan production.