Use of a Constrained Hierarchical Optimization Dataset Enhances Knowledge Based Planning as a Quality Assurance Tool for Prostate Bed Irradiation

To investigate whether building a knowledge based planning (KBP) model with prostate bed plans constructed from constrained hierarchical optimization (CHO) would result in more efficient model construction with more consistent output than a model built using plans from a traditional, trial-and-error based optimization (TEO) technique.

Three KBP models were constructed from plans from subsets of fifty-eight post-prostatectomy patients treated with intensity modulated radiation therapy. TEO54 was built from fifty-four TEO plans, selected to represent typical clinical variations in target and organ-at-risk sizes and shapes. CHO30 and TEO30 were built from the same thirty patients populated with CHO and TEO plans, respectively. The three models were each applied to a new set of eighteen patient scans and dose-volume histogram estimates (DVHEs) were generated for rectal and bladder walls and compared for each patient.

CHO30 resulted in a significantly tighter range in DVHEs (p < 0.01) for both the rectal and bladder walls compared with either of the TEO models, indicating less uncertainty in the dose estimation. Plans resulting from KBP optimization using each model were very similar.

Populating a KBP model with CHO data resulted in a high quality model. Since CHO plans can be generated automatically offline in a process that necessitates little to no user interaction, a CHO-KBP model can quickly adapt to changes in plan evaluation criteria or planning techniques without the need to wait to accrue sufficient numbers of clinical TEO plans. This may facilitate the use of KBP approaches for initial or ongoing quality assurance procedures and plan quality audits. This article is protected by copyright. All rights reserved.

Medical physics. 2018 Aug 31 [Epub ahead of print]

Yen Hwa Lin, Linda X Hong, Margie A Hunt, Sean L Berry

Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima, 734-8551, Japan., Department of Medical Physics, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY, 10065, USA.