Evaluation of Major Factors Affecting Spatial Resolution of Gamma-Rays Camera


The spatial resolution of the gamma-rays camera was measured on a60Co gamma-rays source with edge method. The gamma-rays camera is consisting with rays-fluorescence convertor, optical imaging system, MCP image intensifier, CCD camera, electronic control system and other devices, and is mainly used in the image diagnostics of the intense pulse radiation sources [1]. Due to the relatively big quantum detective efficiency (DQE) and quantum gain of the gamma-rays, etc., the experimental data were processed by averaging multiple images and fitting curves. According to the experimental results, the spatial resolution MTF (modulation transfer function) at the 10% intensity was about 2lp/mm. Meanwhile, because of the relatively big dispersion effects of the fluorescence transmissions in the scintillator and the optical imaging system, the maximal single-noise ratio (SNR) of the camera was found to be about 5:1. In addition, the spatial resolution of the camera was measured with pulse X-rays with 0.3MeV in average energy and exclusion of the effects of secondary electrons from consideration. Accordingly, the spatial resolution MTF at the 10% intensity was about 5lp/mm. This could be an additional evidence to verify the effects of secondary electrons induced by the 1.25MeV gamma-rays in the scintillator upon the spatial resolution. Based on our analysis, the dispersion sizes of the secondary electrons in the scintillator are about 0.4mm-0.6mm. Comparatively, as indicated by the detailed analysis of the spatial resolutions of the MCP image intensifier and CCD devices, both of them have little effect on the spatial resolution of the gamma-rays camera that could be well neglected.

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H. Xie, J. Zhang, J. Chen, F. Zhang, L. Li, J. Qi and Y. Chu, "Evaluation of Major Factors Affecting Spatial Resolution of Gamma-Rays Camera," Journal of Analytical Sciences, Methods and Instrumentation, Vol. 3 No. 4, 2013, pp. 227-233. doi: 10.4236/jasmi.2013.34029.

Conflicts of Interest

The authors declare no conflicts of interest.


[1] S. Watson, T. Kauppila, et al., “The High-Energy Radiographic Machine Emitting X-Rays Flash Radiographic Camera,” SPIE Proceedings, Vol. 2869, 1997, pp. 920-928.
[2] G. J. Yates and N. S. P. King, “High-Frame Intensified Fast Optically Shuttered TV Cameras with Selected Imaging Applications,” SPIE Proceedings, Vol. 2273, 1997, pp. 126-149.
[3] P. B. Gree and T. van Doorn, “Evaluation of an Algorithm for the Assessment of the MTF Using an Edge Method,” Medical Physics, Vol. 27, No. 9, 2000, pp. 2048-2059.
[4] H. Q. Zhu, “Study on the Image Restoration of Y-Ray Pinhole Imaging System,” Ph.D. Thesis, Tsinghua University, Beijing, 2008.
[5] P. Z. Takacs and I. Kotov, “PSF and MTF Measurement Methods for Thick CCD Sensor Characterization,” SPIE Proceedings, Vol. 7742, 20120, Article ID: 774207.
[6] A. Karcher and C. J. Bebek, “Measurement of Lateral Charge Diffusion in Thick Fully Depleted, Back-Illuminated CCDs,” IEEE Transactions on Nuclear Science, Vol. 51, No. 5, 2004, pp. 2231-2237.
[7] H. Schwarzer and A. Boerner, “Dynamic PSF and MTF Measurement on a 9k TDI CCD,” SPIE Proceedings, Vol. 7106, 2008. http://dx.doi.org/10.1117/12.797055
[8] H. Q. Zhu and K. L. Wang, “MTF Measurement and Analysis of Microchannel Plate Image Intensifiers,” Acta Photonica Sinica, Vol. 36, No. 11, 2007, pp. 1983-1986.
[9] J. M. Ma and K. L. Wang, “Research on PSF of Scintillator as g-Ray Fluorescenc Image Converter,” Nuclear Electronics & Detection Technology, Vol. 31, No. 4, 2011, pp. 473-478.
[10] J. H. Zhu and S. L. Niu, “Energy Deposition of Gamma Rays in LSO Crystal,” High Power Laser and Particle Beams, Vol. 22, No. 6, 2010, pp. 1351-1354.

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