# Dysphagia optimized knowledge‐based planning for head and neck cancer

## TL;DR

This study introduces a new model for radiation therapy planning that improves swallowing function by better protecting specific throat muscles.

## Contribution

The novel DO-KBP model improves sparing of swallowing structures through focused data augmentation with individually contoured constrictors.

## Key findings

- DO-KBP reduced mean doses to inferior and superior/middle constrictors significantly.
- DO-KBP plans were clinically preferred despite minor increases in some OAR doses.
- Plan homogeneity remained equivalent between models.

## Abstract

Swallowing dysfunction after radiotherapy (RT) is often linked to pharyngeal mucosal damage. This study aimed to develop a dysphagia‐optimized knowledge‐based planning (DO‐KBP) model by incorporating individual pharyngeal constrictors (DO‐KBP) into an existing model, which was based on a conventional approach of including pharynx as a single structure during treatment planning (P‐KBP).

The P‐KBP model was trained on 175 head and neck cases with the pharynx contoured as a single organ. The DO‐KBP model included 36 additional oropharynx cases (∼20% increase) with individual pharyngeal constrictors delineated. Both models were evaluated on 25 test patients. Treatment plans generated by each model were normalized to planning‐target‐volume (PTV) coverage (D95%), and dosimetric parameters were compared using two‐tailed paired t‐tests. A blind physician review assessed clinical preference.

The DO‐KBP model was able to significantly reduce the mean dose to the inferior constrictor (36.52 ± 9.87 Gy to 19.52 ± 6.23 Gy) and superior/middle constrictors (51.89 ± 6.31 Gy to 47.46 ± 6.12 Gy) (p < 0.05) with the addition of 36 high‐quality treatment plans. Though statistically significant increases in mean dose were observed for the spinal cord PRV (D0.03cc), cochlea, mandible, and left brachial plexus with the DO‐KBP model, these differences were small in magnitude and remained within clinical goals. However, these differences were small in magnitude and remained within clinical goals. Plan homogeneity was equivalent (HI = 0.09). The DO‐KBP plans were preferred in blinded review.

Targeted addition of a small number of cases with individually contoured constrictors to an existing model significantly improved sparing of swallowing structures, without compromising overall plan quality or increasing organs‐at‐risk (OAR) doses beyond clinical thresholds, highlighting that modest, focused data augmentation can yield clinically meaningful gains.