Comparison of static and dynamic intensity-modulated radiotherapy for nasopharyngeal carcinoma: Dosimetric and normal...

With the advancement of radiotherapy techniques for nasopharyngeal carcinoma, it is essential to evaluate the comparative effectiveness of volumetric-modulated arc therapy and intensity-modulated radiotherapy. This study aimed to evaluate the dosimetric and radiobiological differences between the two techniques for the treatment of nasopharyngeal carcinomas.

This retrospective study involved replanning of 125 cases of nasopharyngeal carcinoma using both intensity-modulated radiotherapy and volumetric-modulated arc therapy techniques. Dosimetric evaluation was performed using dose-volume histogram parameters, while radiobiological analysis was conducted using normal tissue complication probability models. Target coverage (dose delivered to 95 % of the high-risk planning target volume), mean dose, and maximum dose to organs at risk, as well as normal tissue complication probability values, were compared between the two techniques.

Both intensity-modulated radiotherapy and volumetric-modulated arc therapy provided comparable dosimetric outcomes. Volumetric-modulated arc therapy showed advantages in certain parameters, with a higher dose delivered to 95 % of the high-risk planning target volume and lower maximum dose for the right and left optic nerves, chiasma, and lenses. Conversely, intensity-modulated radiotherapy provided better sparing of the parotid glands, resulting in lower normal tissue complication probability values. The larynx, pharynx, and thyroid also received lower mean doses with intensity-modulated radiotherapy. The results remained consistent in subgroups of both early and advanced stages of nasopharyngeal carcinoma.

Intensity-modulated radiotherapy and volumetric-modulated arc therapy both have distinct advantages in treating nasopharyngeal carcinoma. Organs at risk protected vary between the two techniques. The radiobiological parameters, including normal tissue complication probability models and dosimetric measures, highlight the differential benefits of each technique.