Selection of beam orientations in intensity-modulated radiation therapy using single-beam indices and integer...

Area of Science:

• Medical Physics
• Radiation Oncology
• Computational Biology

Background:

• Intensity-modulated radiation therapy (IMRT) planning optimizes dose distribution but relies on trial-and-error for beam selection.
• Optimizing beam orientation is crucial for maximizing therapeutic benefit while minimizing dose to organs-at-risk (OARs).

Purpose of the Study:

• To develop and evaluate an integer programming (IP) optimization method for selecting optimal beam orientations in IMRT planning.
• To improve organ-at-risk (OAR) sparing by systematically optimizing beam angles.

Main Methods:

• Developed an IP optimization method using mean organ-at-risk (MOD) data from single-beam plans.
• Discretized beam orientation space and calculated MODs for each orientation.
• Input MOD data into an IP process, solved using the branch-and-cut algorithm, to select optimal beam angles.

Main Results:

• IP-selected beam sets with lower average single-beam MODs yielded IMRT plans with superior OAR sparing compared to manual selection.
• IP-selected beams improved dose-volume metrics by up to 40% for OARs proximal to the planning target volume (PTV).
• OAR dose-volume histograms (DVHs) showed sensitivity to beam selection, with optimized angles outperforming equi-spaced plans.

Conclusions:

• The developed IP optimization method effectively selects beam orientations for IMRT, significantly improving OAR sparing.
• This approach offers a systematic alternative to trial-and-error beam selection, enhancing treatment plan quality.
• Further DVH improvements are achievable by adjusting OAR weights within the IP framework, though trade-offs exist.