Iranian Journal of Medical Physics

Iranian Journal of Medical Physics

Design and Construction of an Affordable Phantom for Electron Density Measurement and Linearity Tests of Computed Tomography Systems

Document Type : Original Paper

Authors
Rezvan Ravanfar Haghighi 1
Sabysachi Chatterjee 2
Sepideh Sefidbakht 1
Reza Jalli 1
Vani Vardhan Chatterjee 3
1 Medical Imaging Research Centre, Shiraz University of Medical Sciences, Shiraz, Iran
2 Ongil, 79 D3, Sivaya Nagar, Reddiyur Alagapuram, Salem 636004. India
3 Department of Instrumentation and Applied Physics, Indian Institute of Science, India, Bangalore
10.22038/ijmp.2019.38317.1492
Abstract
Introduction: The performance of computed tomography is routinely checked using phantoms, which are known as important diagnostic imaging tools. Depending upon the aim of the study, different phantoms are designed, while trying to satisfy certain levels of diversities in their application.
Material and Methods: The present study describes the construction of an inexpensive phantom designed for simultaneous measurements of 12 different samples. The body of the phantom, test tube holders, and test tubes were made of materials of low attenuation coefficient. Body of the phantom was filled with water. Test tubes filled with solutions of known chemical compositions were mounted on the test tube holders.  The whole phantom was scanned at 80, 100, 120, 140 kVp to evaluate the performance of the CT system. Using Hounsfield Unit (HU) data from these liquid samples of known electron density, the phantom was calibrated for electron density measurements.
Results: The system's accuracy and reproducibility were verified by measuring the HU values for some known materials. According to the results obtained from the experimental datawith liquid samples, the accuracy of the water and noise was within ±3.2 HU and 0.6%, respectively. Moreover, the image uniformity error was less than ±2 HU, and CT system's linearity for calibration was estimated with 99.9% confidence.
Conclusion: The present system gives satisfactory results with known samples and can be used with confidence for characterizing unknown materials.
Keywords
Computed Tomography Phantom
Quality Control Attenuation
Photoelectric Effect
Subjects

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Iranian Journal of Medical Physics
Volume 17, Issue 1 - Serial Number 1
January and February 2020
Pages 38-47

  • Receive Date 14 March 2019
  • Revise Date 12 May 2019
  • Accept Date 20 May 2019