Evaluation of Reconstruction Accuracy of 4-D CT Images for Real-Time Position ManagementTM System

Abstract

Moving target volume is a significant problem for cancer treatment. Four-dimensional computed tomography was developed to improve the treatment of this target volume. In the present, respiratory signal are combined with computed tomography images to create the 4 Dimensional Computed Tomography (4-D CT) images. Also, Real-Time Position ManagementTM (RPM) system is the most of choice for 4-D CT imaging. For the most accuracy of the treatment, the system has to be evaluated. Therefore, the purpose of this study was to evaluate the accuracy of reconstructed of 4-D CT images for RPM. 4-D CT images of moving phantom (QUASARTM) with Computed Tomography skin markers (metal beads) were performed by using three different respiratory rates: 10, 15, and 20 beats per minute (BPM). The plastic sphere (simulated tumor) of the moving phantom was simulated to move 2 cm in a longitudinal direction. The accuracy of reconstruction for those images was evaluated in terms of distance error (the displacement of metal bead from the exact position) and volumetric error (the different between the actual and the measured volumes). Results indicated that the accuracy of reconstruction RPM system was acceptable with mean distance and volumetric errors of 0.44±0.10 mm and 0.07±0.06 cm3, respectively. In addition, respiratory rates had no effect on the accuracy of reconstruction. Therefore, the respiratory data acquisition of RPM system in 4-D CT could reconstruct accurate images for moving targets with the respiratory rate of 10-20 BPM which should be suitable for clinical treatment.

Keywords

• 4d computed tomography
• 4-d ct images
• real-time position managementtm
• respiratory motion phantom