In recent years, photon counting CT systems (PCCT) have attracted attention because it can scan high-resolution images at lower doses than conventional energy integrating detector CT systems (EIDCT). However, organ exposure doses of PCCT have not yet been evaluated. In this study, we measured the half-value layer and absorbed dose of NAEOTOM Alpha (PCCT, Siemens Healthineers), at each position and tube voltage, using the Piranha (semiconductor detector, RTI). In addition, we created a source model of NAEOTOM Alpha for organ exposure doses calculation using a human phantom. After that, we verify the X-ray quality and absorbed dose horizontal distribution, using the Monte Carlo simulation code PHITS. The calculation results obtained from the created source model well matched the measurements of actual X-ray source. Therefore, it can be said that the source model created in this study can reproduce the radiation source of NAEOTOM Alpha.

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