Document Type: Original Paper
Medical Imaging Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
Ongil, 79 D3, Sivaya Nagar, Reddiyur Alagapuram, Salem 636004. India
Medical imaging Research Centre, Shiraz University of Medical Sciences, Research Tower, Khalili Street, Shiraz 7193635899, Iran
Department of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore 560012. INDIA
Introduction: Computed Tomography being an important diagnostic imaging tool its performance is routinely checked, by using phantoms. The present paper describes the construction of an inexpensive phantom, designed for simultaneous measurements with 12 different samples. The system's accuracy and reproducibility were verified by measuring the HU values for some known materials.
Materials and methods: The body of the phantom and test tube holders is made of Plexiglas. Plastic test-tubes, made of very low attenuation materials, were filled with solutions of known chemical composition. They were mounted on the test tube holders and scanned at 80, 100, 120, 140 kVp. Body of the phantom was filled with water. Images from this water portion and from the parts containing the solutions were used to evaluate the performance of the CT system. With HU data from these liquid samples of known electron density, the phantom was calibrated for electron density measurements.
Results: Experimental data with liquid samples showed that the accuracy of the HU of water lies within ±3.2, noise within 0.6%, image uniformity error is less than ±2HU and CT system's linearity for calibration has 99.9% confidence.
Conclusion: The present system gives satisfactory results with known samples and can be used with confidence for characterizing unknown materials.