This systematic review presents 2 variables, which are suitable for estimation of radiotherapy-related pharyngeal constrictor muscles changes-magnetic resonance imaging signal intensity and the thickness. Moreover, the changes in magnetic resonance imaging signal intensity of the pharyngeal constrictor muscles correlate with the absorbed dose (typically higher than 50 Gy) and also with the grade of dysphagia. The conclusions of 8 studies that passed the criteria indicate a significant increase in the volume and the thickness of the pharyngeal constrictor muscles during radiotherapy. A literature search was performed in the MEDLINE database according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.
![pharyngeal constrictor pharyngeal constrictor](http://www.thebodyonline.net/head/superior_pharyngeal_constrictor.jpg)
The goal of this review is to summarize the current knowledge about volumetric, dosimetric, and other changes of the pharyngeal constrictor muscles associated with head and neck radiotherapy. increasing, there are only a few studies concerning changes in dysphagia-related structures during radiotherapy. Although the number of studies concerning adaptive radiotherapy of head and neck cancer is continuously. The reduction of radiotherapy-induced dysphagia might be achieved by adaptive radiotherapy. It is well known that radiation damage of the pharyngeal constrictor muscles, the glottic larynx, and the supraglottic larynx may lead to dysphagia, an unwanted effect of head and neck radiotherapy.
![pharyngeal constrictor pharyngeal constrictor](https://pmj.bmj.com/content/postgradmedj/77/910/506/F1.large.jpg)
A clinically acceptable balance must be achieved between OAR dosimetry and target coverage as can be achieved by frequent IG. A nonpredictable, yet significant dosimetric effect was found. Regarding target volumes, a highly significant decrease in MD (MD = 20 Gy, CI: −20.310 to −19.820) in D98 of the high-dose planning target volume (PTV PTVD98% = 70 Gy) for case 3 was found (p ≤ 0.001). A significant decrease in V50 Gy was observed for all PCMs (p < 0.001) on all CBCTs relative to the original plan. No significant time trends were established for these OARs. Results were deemed statistically significant if p < 0.05. Dosimetric endpoints recorded to assess the effect of positional variation were as per ICRU 83 and included D95 and D98 for the target volumes, mean dose (MD) and V30 Gy for the PGs, and V50 Gy and MD for the PCMs. Each plan was recalculated without heterogeneity correction allowing for dosimetric comparison. Intensity modulated radiotherapy (IMRT) plans for 5 locally advanced head and neck patients׳ plans were created and mapped to weekly CBCTs.
![pharyngeal constrictor pharyngeal constrictor](https://teachmeanatomy.info/wp-content/uploads/Location-of-the-Palatine-Tonsils-in-the-Oropharynx.jpg)
Furthermore, this investigation sought to establish a potential time trend of change in dose delivered to target volumes secondary to ascertaining the need for daily image guidance (IG) to reduce the dose burden to these important OARs. With past studies focusing on the quantification of positional and volumetric changes of organs at risk (OARs), this study aimed to measure the dose delivered to these the parotid gland (PG) and pharyngeal constrictor muscles (PCMs) using cone beam computed. With margin reduction common in head and neck radiotherapy, it is critical that the dosimetric effects of setup deviations are quantified.