MRI-based adaptive radiotherapy has the potential to reduce dysphagia in patients with head and neck cancer
Abstract
Purpose:This study explored the potential of MRI-based adaptive radiotherapy to spare dysphagia and aspiration related structures (DARS) in a heterogeneous cohort of patients (n = 23) who received radiotherapy (RT) for different sites of head and neck cancer. Methods: Pharyngeal constrictor muscles (PCM), cricopharyngeal muscle (CPM), proximal part of the esophagus (PE), supraglottic larynx (SGL), and transglottic larynx (TGL) were contoured in weekly MRI during the treatment and considered as DARS.
To compare dysphagia-optimized radiotherapy (DORT) and MRI-based dysphagiaoptimized adaptive radiotherapy (DOART), two data sets were created for each patient using synthetic CTs created by deforming the initial planning CT. Dose-volume histograms (DVHs) of accumulated doses were generated and dosimetric parameters V50Gy - V70Gy and mean doses were measured for DARS and for both DORT and DOART.
Results: he significant improvements in DARS-sparing were observed in regions of the highest doses (95% confidence interval, p < 0.05). For example, V70Gy in PCM decreased from 7.8 +- 5.5% to 2.6 +- 4.4% - this was a reduction by 67% (p < 0.001).
Similarly, the relative decreases of V65 Gy in PCM, V60 Gy in SGL, V60 Gy in TGL, and V55 Gy in CPM were 37%, 32%, 46%, and 27%, respectively. Conclusions: It was shown that MRI-based DOART has the potential to significantly reduce the radiation burden of DARS as a response to the decreasing volume of primary tumor or lymphatic nodes.
Findings of this study provide novel evidence to suggest that the concept of MRI-based DOART could contribute to spare DARS.