ABSTRACT
Objective:To analyze the dosimetric differences between 3D printed oral stents and corked oral stents in the target area and perioral organ at risk (OAR) in radiotherapy for head and neck cancer, and the effectiveness in reducing acute adverse reactions associated with radiotherapy.Methods:A total of 58 patients with head and neck cancer admitted to Department of Oncology of Affiliated Hospital of North Sichuan Medical College were selected and divided into experimental group (Group A, n=28, wearing 3D printed oral stents during radiotherapy) and control group (Group B, n=30, wearing corked oral stents during radiotherapy) in this retrospective cohort study. The incidence of radiotherapy - induced oral mucositis (RTOM), xerostomia and oropharyngeal mucosal pain was compared between two groups. Meanwhile, informed consent was obtained from 21 patients in Group A. Using the self control method, each patient wore a 3D printed oral stent (Group C) and a corked oral stent (Group D) to make two radiotherapy plans. The differences in the conformity index (CI), homogeneity index (HI) and exposure dose of OAR (D max, D mean) in the target area were analyzed between two groups. SPSS 25.0 statistical software was used for statistical analysis. Measurement data were expressed as Mean±SD. Comparison between two groups was conducted by paired t-test or repeated measurement analysis. Count data were expressed as ratio. Comparison between two groups was performed by Chi - square test or Fisher's exact test. P<0.05 was considered as statistically significant difference. Results:The severity of RTOM ( P<0.05), oropharyngeal mucosal pain ( P=0.004) and xerostomia score ( P<0.001) in Group A were significantly lower than those in Group B. There was no significant difference in the HI and CI of the target area between Group C and Group D (both P>0.05). The D max ( P=0.014, 0.009) and D mean ( P<0.001, P=0.033) of the upper lip and the affected buccal mucosa in Group C were significantly lower than those in Group D. Conclusion:3D printed oral stents obtain favorable HI and CI in radiotherapy for head and neck cancer, significantly reduce the irradiated dose to perioral OAR, and effectively lower the incidence and mitigate the severity of acute RTOM, xerostomia and oropharyngeal mucosal pain associated with radiotherapy.
ABSTRACT
BACKGROUND: Radiotherapy for head and neck cancer may cause various oral sequelae, such as radiation-induced mucositis. To protect healthy tissue from irradiation, intraoral devices can be used. Current tissue retraction devices (TRDs) have to be either individually manufactured at considerable cost and time expenditure or they are limited in their variability. In this context, a 3D-printed, tooth-borne TRD might further facilitate clinical use. METHODS: A novel approach for the manufacturing of TRDs is described and its clinical application is analysed retrospectively. The devices were virtually designed for fabrication by 3D-printing technology, enabling-in only a single printing design-caudal or bi-lateral tongue displacement, as well as stabilization of a tongue-out position. For a total of 10 patients undergoing radiotherapy of head and neck tumors, the devices were individually adapted after pre-fabrication. Technical and clinical feasibility was assessed along with patient adherence. Tissue spacing was calculated by volumetric analysis of tongue retraction. In one exemplary case, radiotherapy treatment plans before and after tissue displacement were generated and compared. The reproducibility of maxillomandibular relation at device re-positioning was quantified by repeated intraoral optical scanning in a voluntary participant. RESULTS: 3D-printing was useful for the simplification of TRD manufacture, resulting in a total patient treatment time of less than 30 min. The devices were tolerated well by all tested patients over the entire radiation treatment period. No technical complications occurred with the devices. The TRDs caused an effective spacing of the healthy adjacent tissue, e.g., the tongue. Position changes of maxillomandibular relation were limited to a mean value of 98.1 µm ± 29.4 µm root mean square deviation between initial reference and follow-up positions. CONCLUSIONS: The presented method allows a resource-efficient fabrication of individualized, tooth-bourne TRDs. A high reproducibility of maxillomandibular relation was found and the first clinical experiences underline the high potential of such devices for radiotherapy in the head and neck area.
ABSTRACT
BACKGROUND: To evaluate and establish a digital workflow for the custom designing and 3D printing of mouth opening tongue-depressing (MOTD) stents for patients receiving radiotherapy for head and neck cancer. METHODS: We retrospectively identified 3 patients who received radiation therapy (RT) for primary head and neck cancers with MOTD stents. We compared two methods for obtaining the digital impressions of patients' teeth. The first method involved segmentation from computed tomography (CT) scans, as previously established by our group, and the second method used 3D scanning of the patients' articulated stone models that were made during the conventional stent fabrication process. Three independent observers repeated the process to obtain digital impressions which provided data to design customized MOTD stents. For each method, we evaluated the time efficiency, dice similarity coefficient (DSC) for reproducibility, and the 3D printed stents' accuracy. For the 3D scanning method, we evaluated the registration process using manual and automatic approaches. RESULTS: For all patients, the 3D scanning method demonstrated a significant advantage over the CT scanning method in terms of time efficiency with over 60% reduction in time consumed (p < 0.0001) and reproducibility with significantly higher DSC (p < 0.001). The printed stents were tested over the articulated dental stone models, and the trueness of fit and accuracy of dental anatomy was found to be significantly better for MOTD stents made using the 3D scanning method. The automated registration showed higher accuracy with errors < 0.001 mm compared to manual registration. CONCLUSIONS: We developed an efficient workflow for custom designing and 3D-printing MOTD radiation stents. This workflow represents a considerable improvement over the CT-derived segmentation method. The application of this rapid and efficient digital workflow into radiation oncology practices can expand the use of these toxicity sparing devices to practices that do not currently have the support to make them.
