Discussion
OSMS, breast cancer
BREAST CANCER
This study suggests that the cardiac radiation dose of left-sided breast cancer was significantly reduced by the use of VDIBH. The position of the heart was reproducible during treatment. The median treatment time of 4 min and feedback from patients and therapists indicated that RT using VDIBH and OSMS was acceptable. The PTV margins under VDIBH were <1 cm. In the present study, the heart DPrevious studies on the effects of DIBH on cardiac radiation dose focused on the dosimetric analysis in treatment planning, which did not reflect the actual heart position and dose in daily treatment.Traditional ABC-DIBH devices have been widely used, and their physical benefits have been recognized by many studies. However, the process is complex, and many patients have difficulty accepting it. With the development and widespread use of the OSMS technology, the simpler VDIBH technology can be realized. We verified the accuracy and physical benefits of OSMS-assisted VDIBH. This is, to the best of our knowledge, the first study about the acceptance of OSMS-assisted VDIBH treatment by patients and therapists. A predesigned questionnaire was completed by patients and involved therapists to assess the acceptance of this technique. During the initial positioning, we let all patients experience ABC-DIBH training. With a full score of 15 points, 8 of 9 therapists scored more than 10 points, indicating good acceptance of VDIBH. But the oldest therapist (57 years) gave the lowest total score (3 points). No correlation between scores and age was found after statistical analysis. We also designed a question (No 4: How do you feel about VDIBH gating RT compared with utilization of ABC devices?) to compare the experience of ABC and VDIBH workflow. All patients gave 2 or 3 points, which means that VDIBH is more comfortable than ABC-DIBH.In this study, the proposed PTV margins of 0.49 cm, 0.69 cm, and 0.65 cm in the lateral (L/R), cephalo-caudal (C/C), and ventral-dorsal (V/D) directions, respectively, were comparable with those under DIBH reported in literature (The Corresponding PTV Margins of DIBH Reported in Studies (cm).Abbreviation: DIBH, deep-inspiration breath hold.In this study, VDIBH was thoroughly evaluated with respect to RT planning and technical implementation. The feasibility and physical advantages of the proposed therapy were clarified.This study has limitations. First, in terms of OSMS reference images, no infrared camera was arranged at the CT simulation end, and the reference images of the surface could only be reconstructed based on the outer contour of the positioned CT images. Gierga 