Design and Fabrication Process of CT number Linearity and Homogeneity Phantom CT Scan

Document Type: Conference Proceedings

Authors

1 Department of Medical Physics and Biomedical engineering, Faculty of Medicine, Shahid Beheshti University of Medical Sciences and Health Services, Tehran, Iran

2 Department of Medical Physics and Biomedical Engineering, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Evin, Tehran, Iran

Abstract

Introduction:
One of the most valuable goals of phantoms, replacing with human goals in the field of research and quality control of diagnostic X-ray systems. There are various algorithms and methods for obtaining Homogeneity and CT number linearity for CT scan device. One of the most famous of these methods, the method is to use a uniform and homogeneous environment to compute Homogeneity and as well as the use of different materials with different densities to calculate CT number linearity. Therefore, a phantom was invented for a simple and fast calculation of Homogeneity and CT number linearity parameters for CT scan devices.
Materials and Methods:
Construction of Phantom CT number Homogeneity:
To make this phantom has been used CNC three-axis machine model 2000. First, an acrylic tube is cut with an internal diameter of 154 mm and an external diameter of 160 mm and a length of 30 mm. Then two acrylic disks are cut with a diameter of 154 mm and a thickness of 5 mm. In the middle of one of these disks hole is created a 20 mm diameter, which is filled with a plastic screw. Then these two acrylic disks are attached to the beginning and end of the tube.
Construction of Phantom CT number linearity:
For make this phantom has been used CNC three-axis machine model 2000. Using this device, the PE (Polyethylene), PMMA (Acrylic), PTFE (Teflon), Air, PS (Polystyrene) and PA (Polyamide) rods are cut in 25 mm and 25 mm in length. Then an acrylic disk is cut diameter of 154 mm and a thickness of 5 mm.
 
Results:
This phantom was tested for various CT scan devices. The results obtained from this phantom are equal to the external samples. The CT number Linearity chart obtained from this phantom corresponds to the CT number Linearity Phantom Pro-CT chart.
Conclusion:
This phantom has much less weight than other phantoms. The amount of material used in this phantom is greater than the other similar phantoms. The price of this phantom is very low compared to similar samples. In this phantom, Homogeneity and CT number linearity are calculated with higher precision and more points. Also, this phantom can be used to calculate noise.

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