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Dosimetric study of beam angle optimization in intensity-modulated radiation therapy planning
Arvind Kumar Shukla1, Sanjeev Kumar2, I S Sandhu3
1Department of Radiotherapy, Post Graduate Institute of Medical Education and Research, Chandigarh; Department of Applied Sciences, Punjab Technical University (PTU), Jalandhar, India.
Beam Angle Optimization (BAO) significantly reduces monitor units (MUs) in intensity-modulated radiotherapy (IMRT) planning compared to preselected equiangular beam orientations (PSBO). BAO offers comparable or improved organ-at-risk sparing and plan quality, making it a superior choice for IMRT.
Area of Science:
- Radiation Oncology
- Medical Physics
- Radiotherapy Planning
Background:
- Intensity-modulated radiotherapy (IMRT) quality is influenced by beam orientation and optimization algorithms.
- Effective IMRT planning requires careful selection of beam angles to balance target coverage and organ-at-risk (OAR) sparing.
Purpose of the Study:
- To compare dosimetric outcomes of IMRT plans generated using preselected equiangular beam orientations (PSBO) versus beam angle optimization (BAO).
- To evaluate the impact of BAO on monitor units (MUs), OAR doses, target coverage, and plan quality indices.
Main Methods:
- Dosimetric comparison of IMRT plans from 30 patients (prostate, head and neck, esophagus carcinoma).
- Two plans per patient: one with PSBO (7-9 coplanar fields), one with BAO using a computerized algorithm.
- Comparison based on MUs, OAR doses, conformity index (CI), homogeneity index (HI), and quality index (QI) using dose-volume histograms (DVHs).
Main Results:
- BAO plans resulted in identical or slightly better OAR doses compared to PSBO plans.
- Conformity Index, Homogeneity Index, and Quality Index values were comparable between PSBO and BAO plans.
- A significant reduction in delivered monitor units (MUs) was observed for all BAO-generated plans.
Conclusions:
- Beam Angle Optimization (BAO) is a superior method for IMRT planning, primarily due to significant reductions in monitor units.
- BAO should be implemented in clinical practice whenever feasible to optimize IMRT treatment plans.
