Counting-loss correction procedure of X-ray imaging detectors with consideration for the effective atomic number of biological objects

It is necessary to correct counting loss caused by the pulse pile-up effect and dead time when using energy-resolving photon-counting detectors (ERPCDs) under “high-counting-rate” conditions in medical and/or industrial settings. We aimed to develop a novel counting-loss correction procedure in which biological objects having effective atomic numbers ( Z eff values) of 6.5–13.0 are measured with polychromatic X-rays. To correct for counting loss, such a procedure must theoretically estimate the count value of an ideal X-ray spectrum without counting loss. In this study, we estimated the ideal X-ray spectrum by focusing on the following two points: (1) the X-ray attenuation in an object ( Z eff values of 6.5–13.0) and (2) the detector response. Virtual materials having intermediate atomic numbers between 6.5 and 13.0 were generated by using a mixture of polymethylmethacrylate (PMMA, Z eff = 6.5) and aluminum (Al, Z eff = 13.0). We then constructed an algorithm that can perform the counting-loss correction based on the object's true Z eff value. To demonstrate the applicability of our procedure, we analyzed investigational objects consisting of PMMA and Al using a prototype ERPCD system. A fresh fish sample was also analyzed. The Z eff values agree with the theoretical values within an accuracy of Z eff ±1. In conclusion, we have developed a highly accurate procedure for correcting counting losses for the quantitative X-ray imaging of biological objects. • A procedure for correcting counting loss in photon-counting detectors was proposed. • The effective atomic number ( Z eff ) of the object was considered for correction. • Our method is applicable to biological objects having Z eff of 6.5–13.0. • Applicability was evaluated experimentally by creating an Z eff image. • The accuracy of the Z eff image was achieved to within ± 1.