| Summary: | 碩士 === 中臺科技大學 === 醫學影像暨放射科學系暨研究所 === 102 === In recent years image-guided radiation therapy (IGRT) is a new technology. Use of image-guided positioning system to obtain 3D CBCT and automatic image-guided positioning verification patient position can be determined accurately ,while receiving additional dose, additional doses also increase the probability of a random normal tissue induced cancer. The purpose of this study uses CBCT measurements dose in adult tissue equivalent anthropomorphic Rando phantom.Use metal oxide semiconductor field effect transistor (MOSFET) measurements of head and neck and chest were five parts each measuring point. Take as conditions to reduce mAs, reduced scan angle and time, for each set of parameters were measured to reduce skin absorbed dose and image can be used feasibility. The results show that use of higher mAs to stable calibration, scan images less than 343 the number of projection, due to insufficient number of projection to makes the distortion of contour, spatial resolution to identify six sets of chest conditions100%、95%、85%、75%、65%、55%,respectively. were each scored 11 lp/cm、11 lp/cm、10 lp/cm、10 lp/cm、10 lp/cm, 9 lp/cm,respectively. However, no significant difference from 100% to 55% of the chest image. Head and neck 100% and 95% of the surface dose similar and chest 100% and 55% of the surface dose decreased to about half the dose. Both the use of automated image fusion to compared residual was no significant. This study shows that taking the appropriate adjustments as conditions. The advantages (1) to reduce the patient moves during the scan. (2) patients reduces received dose. (3) because the patient is limited by the machine size can be flexibly applied. (4) reduce the image storage space. CBCT more expansion range of applications in the clinical, and it will provide the reference for the clinical.
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