Development of a novel method based on a photon counting technique with the aim of precise material identification in clinical x-ray diagnosis

Natsumi Kimoto; Hiroaki Hayashi; Takashi Asahara; Yuki Kanazawa; Tsutomu Yamakawa; Shuichiro Yamamoto; Masashi Yamasaki; Masahiro Okada

doi:10.1117/12.2253564

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9 March 2017 Development of a novel method based on a photon counting technique with the aim of precise material identification in clinical x-ray diagnosis

Natsumi Kimoto, Hiroaki Hayashi, Takashi Asahara, Yuki Kanazawa, Tsutomu Yamakawa, Shuichiro Yamamoto, Masashi Yamasaki, Masahiro Okada

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Proceedings Volume 10132, Medical Imaging 2017: Physics of Medical Imaging; 1013239 (2017) https://doi.org/10.1117/12.2253564
Event: SPIE Medical Imaging, 2017, Orlando, Florida, United States

Abstract

A photon counting system has the ability of energy discrimination, therefore obtaining new information using X-rays for material identification is an expected goal to achieve precise diagnosis. The aim of our study is to propose a novel method for material identification based on a photon counting technique. First, X-ray spectra at 40-60 kV were constructed using a published database. Second, X-ray spectra penetrating different materials having atomic numbers from 5-13 were calculated. These spectra were divided into two energy regions, then linear attenuation factors concerning these regions were obtained. In addition, in order to accomplish highly accurate material identification, correction of beam hardening effects based on soft-tissue was applied to each linear attenuation factor. Then, using the linear attenuation factors, a normalized linear attenuation coefficient was derived. Finally, an effective atomic number was determined using the theoretical relationship between the normalized linear attenuation coefficient and atomic number. In order to demonstrate our method, four different phantoms (acrylic, soft-tissue equivalent, bone equivalent, and aluminum) were measured using a single-probe-type CdTe detector under the assumption that the response of the single-probe-type CdTe detector is equal to the response of one pixel of a multi-pixel-type photon counting detector. Each of these phantoms can be completely separated using our method. Furthermore, we evaluated an adoptive limit of beam hardening correction. We found that the adoptive limit depends on the mass thickness and atomic number. Our vision is to realize highly accurate identification for material with narrow range in atomic number.

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Natsumi Kimoto, Hiroaki Hayashi, Takashi Asahara, Yuki Kanazawa, Tsutomu Yamakawa, Shuichiro Yamamoto, Masashi Yamasaki, and Masahiro Okada "Development of a novel method based on a photon counting technique with the aim of precise material identification in clinical x-ray diagnosis", Proc. SPIE 10132, Medical Imaging 2017: Physics of Medical Imaging, 1013239 (9 March 2017); https://doi.org/10.1117/12.2253564

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