Wearing individualized 3D printed oral stent to protect normal tissues in patients with nasopharyngeal carcinoma during radiotherapy.

Abstract

To demonstrate a new individualized 3D printed oral stent in radiotherapy of nasopharyngeal carcinoma (NPC) patients and carry out a comparative analysis combining with clinical case. Thirty NPC patients treated in our institution from September 2021 to October 2022 were prospectively enrolled. An individualized 3D printed oral stent was designed for each patient, and one set of computed tomography (CT) slices were obtained with /without wearing the oral stent, respectively. After delineation of target volumes and organs at risk (OARs) on the two CT slices, we finished two treatment plans by using the same target objectives, critical constraints and plan setup for each patient. Finally, the dose distribution and other dosimetric parameters of target volumes and OARs between the two plans were compared. Tongue volume and tongue length outside of mouth was 10.4±2.5cm3 and 2.8±0.6cm, respectively, distance between dorsal surface of oral tongue and plate increased from 0.3±0.3cm to 2.2±0.5cm by wearing the oral stent. For the target volume, there was no significant difference. However, Dmax of tongue, tongue tip and periglottis decreased significantly from 6352.6±259.9cGy to 5994.9±478.9cGy, 3499.8±250.6cGy to 3357.7±158.0cGy and 6345.5±171.0cGy to 6133.4±263.3cGy, respectively (p=0.000); Dmean of tongue, tongue tip and periglottis decreased significantly from 3714.7±204.2cGy to 3169.7±200.9cGy, 3060.8±216.2cGy to 2509.6±196.7cGy and 3853.3±224.9cGy to 3079.3±222.0cGy, respectively (p=0.000). The individualized 3D printed oral stent can reduce the dose of oral tissues and organs, so as to reduce the oral adverse reactions and improve the compliance of patients and the quality of their life. The technique can be used in radiotherapy of NPC patients.