Sci—Thurs PM: Planning—10: Commissioning a Four‐Dimensional Computed Tomography System for Clinical Implementation

We recently acquired four‐dimensional computed tomography (4DCT) capabilities at our centre with the installation of the Varian Real‐time Position Management (RPM) System (Varian Medical Systems, Palo Alto, CA) and pulmonary gating software for our Philips Brilliance Big Bore scanner (Philips Healthcare, Andover, MA). A CIRS Dynamic Thorax Phantom (Model 008) was also purchased for commissioning and quality assurance purposes (Computerized Imaging Reference Systems, Inc., Norfolk, VA). This work describes the results of the tests used to commission the 4DCT system for clinical implementation. Aspects of the 4DCT system tested to date are volume reconstruction accuracy, CT number accuracy, positional accuracy, and the computed tomography dose index (CTDI) for the 4DCT protocol used in this work. Volume and CT number reconstruction accuracy of the system is comparable to previously reported values, and our positional accuracy is on the order of a millimeter. Measurements of the CTDI volfor the protocol used in this work indicate that the average absorbed dose over a given scan volume is an order of magnitude higher than a standard CT scan. We consider the performance of the 4DCT system to be acceptable and are therefore ready to implement it clinically.