Kazuki Takegami

[Measurement of response function of CdTe detector using diagnostic X-ray equipment and evaluation of Monte Carlo simulation code].

An X-ray spectrum measured with CdTe detector has to be corrected with response function, because the spectrum is composed of full energy peaks (FEP) and escape peaks (EP). Recently, various simulation codes were developed, and using them the response functions can be calculated easily. The aim of this study is to propose a new method for measuring the response function and to compare it with the calculated value by the Monte Carlo simulation code. In this study, characteristic X-rays were used for measuring the response function. These X-rays were produced by the irradiation of diagnostic X-rays with metallic atoms. In the measured spectrum, there was a background contamination, which was caused by the Compton scattering of the irradiated X-ray in the sample material. Therefore, we thought of a new experimental methodology to reduce this background. The experimentally derived spectrum was analyzed and then the ratios of EP divided by FEP (EP/FEP) were calculated to compare the simulated values. In this article, we showed the property of the measured response functions and the analysis accuracy of the EP/FEP, and we indicated that the values calculated by Monte Carlo simulation code could be evaluated by using our method.

A fundamental experiment for novel material identification method based on a photon counting technique: Using conventional X-ray equipment

An imaging technique based on photon counting is attracting attention as a next-generation type X-ray diagnostic technique, because this method has the possibility to identify materials. Various X-ray detectors for photon counting have been newly manufactured, and in the near future we may be able to utilize them in clinical settings. The aim of this paper is to propose a novel method which can provide information concerning the effective of atomic number on material identification. In order to verify the feasibility of this method, a basic experiment was carried out; using a single-channel CdTe detector and diagnostic X-ray equipment, four different materials made from aluminum, bone, acrylic and soft-tissue were identified. Although our experiment is tentative, we found the possibility to apply this research to next-generation type X-ray diagnosis.