Development of nasopharyngeal carcinoma radiotherapy positioning of CT/MRI image registration auxiliary device

Abstract

Objective Developing a CT/MRI image registration assistant device for radiotherapy localization of nasopharyngeal carcinoma, to achieve precise fusion, and by analyzing the differences of the outline to test the application of the registration and fusion image. Methods Design a specific shape pillow for the head-neck coil of MRI, which could keep the patient have the same position form for CT scan. Using paired t-test to analyze the difference of the parotid gland and the mandible. Results After adopting the new device, the registration accuracy has a significant improvement for the head and neck CT and MRI image registration. Comparing two sets of image outline volume, the outlined volume of parotid gland in CT image is smaller than that of CT/MRI fusion image Left parotid gland volume comparison: fusion (17.78±6.89) cm3 and CT(17.17±7.02)cm3(t=-2.715, P<0.05). Right parotid gland volume was (19.23±8.91)cm3 for fusion, and (17.47±7.42) cm3 CT for(t=-2.552, P<0.05), and the size of the mandible was larger than that of CT/MRI fusion image.Left mandible volume was (33.7±5.59) cm3 for fusion, and (34.8±6.27) cm3 for CT (t=3.548, P<0.05). Right mandible volume was (34.46±6.08) cm3 for fusion, and (35.38±6.72)cm3 for CT(t=3.14, P<0.05). Conclusions The accurate image fusion of head and neck CT and, MRI could be achieved with this device, which might be helpful for the delineation of clinical target volume. Key words: Radiation therapy; Nasopharyngeal carcinoma positioning; CT/MRI; Image registration; Image fusion