Thermoplastic masks are a specific type of medical mask used to immobilize the patient's head, neck, shoulder, chest, and other areas during radiation therapy. These masks are crafted from a thermoplastic material that becomes pliable when heated and solidifies upon cooling. This property allows the mask to be molded precisely to the contours of the patient's face, ensuring a customized fit.

Primarily, these masks find application in patients undergoing radiation therapy for head and neck cancers. By keeping the patient's head immobilized during treatment, they play a crucial role in delivering radiation precisely to the intended area.

Thermoplastic masks are classified based on their rigidity and thickness. The thickness of the mask is a critical factor that can influence the accuracy of radiation therapy. Hence, selecting the appropriate mask for each patient is of utmost importance.

In conclusion, thermoplastic masks serve as a vital tool in radiation therapy, significantly enhancing the precision and efficacy of treatment.