Study on the correlation between mouthplate and positioning error in radiotherapy for head and neck tumor

ObjectiveTo explore the effect of mouthplate on the positioning error of head and neck tumor by using the positioning data obtained from helical tomotherapy system, to provide reference for preventing and reducing the adverse reactions of radiotherapy for head and neck tumor.

MethodsTwenty-five patients with head and neck tumor were selected and divided into observation group (13 cases) and control group (12 cases).The observation group was fixed with thermoplastic film and mouthplate, and the control group was fixed with thermoplastic film.MVCT images were used to analyze the positioning errors of the two groups in X-axis, Y-axis, Z-axis and ROLL direction.

ResultsThe positioning error in X-axis and ROLL direction in observation group was significantly less than that in control group (P < 0.01), and the positioning error in Z-axis was higher than that in control group (P < 0.05).There was no significant difference in positioning error in Y-axis between the two groups (P>0.05).In the X-axis and Y-axis, the positioning error was 0-2 mm, and the low error distribution in X-axis and Y-axis in observation group was higher than that in control group (P < 0.01 and P < 0.05).The positioning error in Z-axis mainly distributed in the range of >2.1 mm, and the high error distribution in observation group was significantly higher than that in control group (P < 0.01).The positioning error in ROLL direction mainly distributed in the range of 0-1.0 mm, and the low error distribution in observation group was significantly higher than that in control group (P < 0.01).

ConclusionsThe mouthplate can reduce the positioning error to a certain extent.For patients with no obvious difficulty in opening mouth and good tolerance, mouthplate can be used to reduce the radiotherapy-related adverse reactions in head and neck tumor patient.