1160 - Efficacy of Thermoplastic Mask Heating before Radiotherapy in Reducing Setup Error for Patients with Gynecological Tumor: A Randomized Controlled Study

R. Wang¹, and F. Bai²; ¹Department of Radiation Oncology, Xijing Hospital, Fourth Military Medical University., Xi’an, shaanxi, China, ²Department of Radiation Oncology, Xijing Hospital, Fourth Military Medical University, xian, Shaanxi, China

Purpose/Objective(s): Positional fixation techniques are crucial for radiotherapy because position change during treatment directly causes radiation dose deviations in the target area. Our previous study found temperature differences between body thermoplastic mask and surface skin was an important negative factor for setup accuracy. Therefore, we designed a randomized controlled study to evaluate the efficacy of thermoplastic mask heating before radiotherapy in reducing setup error for patients with gynecological tumor. Materials/

Methods: All patients with gynecological tumor were enrolled in this study according to inclusion and exclusion criteria from May 2023 to February 2024. Patients were randomly divided into heating group(Group A) and non-heating group(Group B). For the heating Group, the thermoplastic mask was placed in a 37 ? incubator and heated for 10 minutes before immobilization. For the non-heating group, the thermoplastic masks with room temperature (room temperature 21-25 ?) were directly used for immobilization. Cone beam computed tomography (CBCT) was used to measuring setup error once a week. Patient comfort was evaluated using a modified Likert questionnaire for the first and sixth treatment sessions. Radiation therapy toxicity was assessed once weekly before and during treatment using CTCAE V5.0. The primary endpoint of this study was setup errors. The secondary endpoint included patient comfort and Differdifference in acute toxic effects of radiotherapy. Registration number was ChiCTR230072088.
Results: A total of 80 patients were enrolled in the study. The median age of all patients was55 (range: 34-76 ). The baseline characteristics between two groups were well-balance. AB Comparison of setup errors between two groups: X direction (0.42 ± 1.63) VS. (0.66 ± 1.62) mm (p=0.132), Y direction (-0.13 ± 2.79) VS. (-0.23 ± 2.99) mm (p=0.729), Z direction (-0.19 ± 1.73) VS. (-0.57 ± 1.97) mm, (p=0.04), RTN direction (- 0.10 ± 0.64) VS. (0.16 ± 0.82) (p <0.001). The margin values of group A and B in the X?Y and Z directions are (3.24, 5.74, 3.57) mm vs. (3.12, 6.01, 4.13) mm. There were no significant differences in the comfort scores before treatment between the two groups (30.73 ± 2.11 vs. 30.33 ± 1.60, p=0.356). and during treatment was (32.98 ± 2.19) VS (30.38 ± 1.50) (p <0.001) . In the comfort questionnaire, only the scores of temperature comfort items in the treatment of group A and group B were significantly different (4.40 ± 0.63) Vs (2.62 ± 0.85) (p <0.001), and the other items were not different. There was no statistically significant differences in acute toxicities of the upper digestive tract, lower digestive tract and urinary system of the two groups.
Conclusion: The results of this study show that thermoplastic mold heating improves the comfort of patients in radiotherapy without increasing the toxicity of the patients, and reduces the errors in translation and rotation caused by the difference in the temperature of the molds, which is worthy of wide application in clinical practice.