CURRENT ROLE OF DUAL-ENERGY COMPUTED TOMOGRAPHY IN PREDICTING THE CHEMICAL COMPOSITION OF THE URINARY STONES AND RADIATION CONCERNS.

Narendra Singh Rathore, Shaveta Yadav, Ning Tu and Guangyao Wu*

ABSTRACT

Dual-energy CT (DECT) has shown excellent outcomes in differentiating the chemical composition of the urinary stones with a great accuracy. Several in-vivo and ex-vivo studies have validated the results. Simultaneous dual-source scans with two x-ray tubes of 80 and 140 kV[45, 14], a single-source scan with dual-layer detector[37, 38] and Rapid switching technique are the commonly used data acquisition techniques, with each having some merits and demerits over each other. The ability of dual-energy CT to differentiate two materials depends on the characteristic CT number ratio of each material. The difference between the CT number ratios for any two materials is determined by the separation between the low and high energy spectra and the effective atomic numbers of the materials.[15] Both material-specific and diagnostic images are created from a single acquisition. The installation of a tin filtration equipment on the newer generation dual energy scanners have resulted in better spectral separation and has made it easy to further differentiate the non-uric acid stone types. Radiation exposure is a prime concern regarding the use of DECT. The amount of radiation exposure to the patients depends on the scanning technique used as well as the part of body to be covered. The implementation of radiation protection strategies during dual energy scanning, such as automated tube current modulation, iterative reconstruction techniques, and designing of improved detector can decrease electronic noise and thus may help to further reduce the radiation dose of DECT.

Keywords: Urolithiasis; Dual-energy CT; DECT; Radiation.