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A Novel Method Based on Monte Carlo for Simulation of Variable Resolution X-ray CT Scanner: Measurement of System Presampling MTF

Authors: H. Arabi, A.R. Kamali Asl


The purpose of this work is measurement of the system presampling MTF of a variable resolution x-ray (VRX) CT scanner. In this paper, we used the parameters of an actual VRX CT scanner for simulation and study of effect of different focal spot sizes on system presampling MTF by Monte Carlo method (GATE simulation software). Focal spot size of 0.6 mm limited the spatial resolution of the system to 5.5 cy/mm at incident angles of below 17º for cell#1. By focal spot size of 0.3 mm the spatial resolution increased up to 11 cy/mm and the limiting effect of focal spot size appeared at incident angles of below 9º. The focal spot size of 0.3 mm could improve the spatial resolution to some extent but because of magnification non-uniformity, there is a 10 cy/mm difference between spatial resolution of cell#1 and cell#256. The focal spot size of 0.1 mm acted as an ideal point source for this system. The spatial resolution increased to more than 35 cy/mm and at all incident angles the spatial resolution was a function of incident angle. By the way focal spot size of 0.1 mm minimized the effect of magnification nonuniformity.

Keywords: Focal spot, Spatial resolution, Monte Carlosimulation, Variable resolution x-ray (VRX) CT.

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[1] J. Beutel, H. L. Kundel, and R. L. van Metter, Handbook of Medical Imaging. Physics and Psychophysics 1. SPIE Press Bellingham, 2000.
[2] G. Wang, S. Zhao, H. Yu, C. Miller, P. Abbas, B. Gantz, S. Lee, and J. Rubinstein, "Design, analysis and simulation for development of the first clinical micro-CT scanner," Acad. Radiol., vol. 12, pp. 511-525, 2005.
[3] A. Sasov and D. van Dyck, "Desktop x-ray microscopy and microtomography," J Microsc, vol. 191, pp. 151-158, 1998.
[4] F. A. DiBianca, V. Gupta, and H. D. Zeman, "A variable resolution xray detector for computed tomography: I. Theoretical basis and experimental verification," Med Phys, vol. 27:8, pp. 1865-1874, 2000.
[5] F. A. DiBianca, P. Zou, L. M. Jordan, J. S. Laughter, H. D. Zeman, and J. Sebes, "A variable resolution x-ray detector for computed tomography: II. Imaging theory and performance," Med Phys, vol. 27:8, pp. 1875-1880, 2000.
[6] F. A. DiBianca, R. Melnyk, C. N. Duckworth, S. Russ, L. M. Jordan, and J. S. Laughter, "Comparison of VRX CT scanners geometries," Proc. SPIE,vol. 4320, pp. 627-635, 2001.
[7] K. Rossmann, "Point spread-function, line spread-function, and modulation transfer function. Tools for the study of imaging systems," Radiology, vol. 93, pp. 257-272, 1969.
[8] J. L. Lancaster, "Physics of Medical X-Ray Imaging." II.html. Accessed 20 jan 2008.
[9] M. L. Giger and K. Doi, "Investigation of basic imaging properties in digital radiography. I. Modulation transfer function," Med. Phys, vol. 11, pp. 287-295 1984.
[10] H. Fujita, K. Doi, and M. L. Giger, "Investigation of basic imaging properties in digital radiography. 6. MTFs of II-TV digital imaging systems," Med Phys, vol. 12, (), pp. 713- 720 1985.
[11] J. T. Dobbins, "Effects of undersampling on the proper interpretation of modulation transfer function, noise power spectra, and noise equivalent quanta of digital imaging systems," Med Phys, vol. 22, pp. 171-181, 1995.
[12] H. Fujita, D. Y. Tsai, T. Itoh, K. Doi, J. Morishita, K. Ueda, and A. Ohtsuka, "A simple method for determining the modulation transfer function in digital radiography," IEEE Trans Med Imaging, vol. 11, pp. 34-39 1992.
[13] J. T. Dobbins, D. L. Ergun, L. Rutz, D. A. Hinshaw, H. Blume, and D. C. Clark, "DQE(f) of four generations of computed radiography acquisition devices," Med Phys, vol. 22, pp. 1581-1593, 1995.
[14] E. Samei, N. T. Ranger, J. T. I. Dobbins, and Y. Chen, "Intercomparison of methods for image quality characterization. I. Modulation transfer function," Med Phys, vol. 33, pp. 1454-1465, 2006.
[15] R. Melnyk and F. A. DiBianca, "Modeling and measurement of the detector presampling MTF of a variable resolution x-ray CT scanner," Med Phys, vol. 34:3, pp. 1062-1075, 2007.
[16] S. Jan, G. Santin, D. Strul, S. Staelens, K. Assie, D. Autret et al "GATE: a simulation toolkit for PET and SPECT," Physics in medicine and biology, vol. 49:19, pp. 4543-4561, 2004.
[17] J. H. Siewerdsen, A. M. Waese, D. J. Moseley, S. Richard, and D. A. Jaffray, "Spektr: a computational tool for x-ray spectral analysis and imaging system optimization," Med Phys, vol. 31:11, pp. 3057-3067, 2004.
[18] H. Arabi, A. R. Kamali Asl, S. M. R. Aghamiri "The Effect of focal spot size on the spatial resolution of variable resolution x-ray CT scanner," Iranian Journal of Radiation Research, To be published.