The Positioning Accuracy of Individualized Open-Face Mask in Patients with Intracranial Tumors Receiving Radiotherapy - A Randomized Controlled Study

• Published in: International journal of radiation oncology, biology, physics Vol. 120; no. 2; p. e102
• Main Authors: Bo, L., Yang, F.T., Zang, J., Bai, F.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.10.2024
• ISSN: 0360-3016
• DOI: 10.1016/j.ijrobp.2024.07.2007

The thermoplastic head mask, when used in combination with Styrofoam, is a prevalent method of immobilization for patients undergoing radiotherapy for intracranial tumors at our center. However, a significant drawback of this fixation technique is its full-face coverage, which frequently causes discomfort for patients, making the mask feel overly constrictive and sometimes even leading to breathing difficulties, nervousness and anxiety. We designed an individualized open-face mask to improve patient comfort without compromise positioning accuracy. The aim of this study was to evaluate the positioning accuracy between traditional head mask and individualized open-face mask in patients with intracranial tumors receiving radiotherapy. Patients with intracranial tumors receiving radiotherapy were randomly divided into traditional head mask (THM) group and individualized open-face mask (IOFM) group at 1:1 ratio. The IOFM was designed as an open area at traditional mask area according to individual facial profile (upper boundary: lower edge of the nasal tip; lower boundary: 1.5CM below the lower lip edge; left and right boundaries: 1CM outside of the corners of the mouth on both sides). All patients received Styrofoam auxiliary fixation. Cone beam computed tomography (CBCT) was performed once a week during radiotherapy for recording the set-up errors in the three directions. Patient comfort was evaluated using a modified Likert questionnaire for the first and sixth treatment sessions. A total of 103 patients were enrolled in this study. 51 patients were immobilized using IOFM method and 52 were immobilized using THM method. The baseline characteristics of two groups were well balance. Analysis of the 593 CBCT data showed that there were no significant differences in set-up errors between IOFM group and THM group (X direction, 1.07±0.89 mm vs 1.02±0.93 mm, p = 0.501; Y direction, 1.23±0.88 mm vs 1.24±0.98 mm, p = 0.921; Z direction, 1.15±0.89 mm vs 1.15±0.84 mm, p = 0.930；rotation error，0.89±0.84 °vs 0.92±1.02°, p = 0.793). The set-up errors in the open area of face between IOFM group and THM group were 1.39±1.09 mm vs 1.28±1.14 mm, p = 0.204 in X direction, 1.77±1.36 mm vs 1.61±1.29 mm, p = 0.160 in Y direction, 1.38±0.90 mm vs 1.25±0.94 mm, p = 0.085 in Z direction, and 1.13±0.94 °vs 1.11±1.04 °, p = 0.875 in rotation error, without significantly statistical differences in two groups. The modified PTV boundaries in the X, Y, and Z directions were 2.48 mm, 3.09 mm, and 2.54 mm in IOFM group and 3.03 mm, 3.37 mm, and 2.43 mm in THM group, respectively. The comfort scores of patients in the IOFM group were higher on both occasions compared with THM group, (32.60±2.36 vs 31.13±1.28, p<0.001) and (33.00±1.66 vs 30.75±1.77, p<0.001). The individualized open-face mask could improve patient comfort without compromise positioning accuracy. It is worth promoting and using in clinical positioning. The registration number of this trial was ChiCTR2300073789.