Based on the collision of intense laser and relativistic electrons, a Thomson scattering x-ray source can produce quasi-monochromatic x-ray pulses with high brightness in the tens keV or even higher energy regime, which can eliminate the beam hardening effect encountered in computed tomography (CT) by using polychromatic x-rays generated through Bremsstrahlung and make it possible to relate the reconstructed linear attenuation coefficients to the composition of a material. In this paper, we demonstrate the capacity of quantitative CT measurement based on Tsinghua Thomson scattering X-ray source (TTX) and the potential of anatomical segmentation using quantitative linear attenuation coefficient analysis. A peanut sample (Arachis hypogaea L.) was chosen for this study. According to the reconstructed CT image, all anatomical structures except for the testa (i.e. the seed coat) of peanut were identified clearly in terms of the shape and size, and there were high similarities between reconstructed linear attenuation coefficients of cotyledon and its theoretical values. After quantitative analysis of the reconstructed linear attenuation coefficients, the hull can be peeled off the core at the threshold of 0.31 cm-1. Our results pave the way towards fundamental researches and practical applications based on quantitative CT at TTX.