Document Type : Research
Authors
1 Department of nuclear engineering, Shiraz University, Shiraz, Fars, Iran
2 Center for Advanced Diffusion-Wave and Photoacoustic Technologies, Dept. of Mechanical and Industrial Engineering, University of Toronto, Toronto, Canada.
Abstract
In this study, the attenuation and scattering behavior of photons in healthy and cancerous liver tissues was investigated using linear attenuation coefficient (μ) diagrams, differential scattering intensity, and contributions of different physical processes. The results show that the linear attenuation coefficients for both types of liver tissue are very close, with only minor differences observed in the energy range below 50 keV. At low energies, the photoelectric effect plays a dominant role in photon attenuation; however, its contribution decreases with increasing energy, and Compton scattering becomes the predominant mechanism. The scattering curves for 20 keV photons also show good agreement with the predictions of Compton theory and the Klein–Nishina formula, such that scattering intensity decreases with increasing angle, with slight differences observed between healthy and cancerous tissues at small angles. The analysis of each physical process's contribution to attenuation indicates that above 50 keV, Compton scattering accounts for more than 90% of total attenuation. In contrast, the contributions of the photoelectric and Rayleigh effects are negligible. Additionally, the ratio of the attenuation coefficient of cancerous tissue to that of healthy tissue decreases with increasing energy, reaching approximately 1.1 at 15 keV and then decreasing to 1.03 at 50 keV. These results suggest that using lower energies (approximately 15–30 keV) can enhance image contrast in liver tumor detection. Therefore, the findings of this study can serve as a basis for optimizing medical imaging protocols for the early diagnosis of liver cancer.
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