Application Of Computed Tomography And Magnetic Resonance Scan Position Consistency On Registration Images In Nasopharyngeal Carcinoma Intensity Modulated Radiotherapy

Objective: To establish test model consistency of the body position on computed tomography(CT) and magnetic resonance(MR) scanners by MR scanning headrest and set marking. To explore the position consistent scanning CT and MR for nasopharyngeal carcinoma intensity modulated radiotherapy images registration feasibility, accuracy and clinical application of value analysis. Methods: The four groups each twenty consecutive patients were pathologic diagnosis patients with NPC and enrolled in this study. Each patient underwent CT and MR scan in the planned treatment. The first group in MR scans without the use of scanning headrest and the body surface mark. The second group requires the use of scanning headrest when MR scanning,the third group requires at CT positioned at the body surface and set the mark and reset it before MR scanning, the fourth group requires both use the scan headrest and reset mark before MR scanning. After the end of the scan image transmission to the Concentra Master plan workstation, automatic registration using image registration software, After registration is completed using image tool to measure mandibular chin to the external occipital carina keel midline spacing of two scanning pitch, compare the difference measurement values of each group under the two images, respectively. Each group to calculate the disparity between the two scanning pitch, then measuring disparity in the pitch difference between comparison groups. Results: Only the second group of measurements are similar under two kinds of images(P=0.300), the first, third and fourth groups of measurements in MRI and CT images are under numerical differences(P=0.017,0.000,0.028). Differences in four groups the difference between the pitch measurement data compare the overall distribution(P=0.000). Multiple comparisons between groups, the first group were differences with the second, third and fourth groups measured distance difference(P=0.000,0.000,0.000). Conclusions: Application of MR scanning headrest and body surface mark methods have helped to improve the CT and MR scans postural positioning consistency,improved the accuracy of CT and MR image fusion significantly.