Woodruff School of Mechanical Engineering

NRE/MP Seminar

Nuclear & Radiological Engineering and Medical Physics Programs


Low-Dose and Single-Scan Dual-Energy CT


Mr. Michael Petrongolo


Georgia Tech


Thursday, September 10, 2015 at 11:00:00 AM


Boggs Building, Room 3-47


Dr. Lei Zhu


Despite recent clinical success, dual energy CT (DECT) imaging is fundamentally limited by noise amplification during signal decomposition and the need for high and low energy data sets. To reduce noise, conventional noise suppression algorithms limit signal variation between neighboring pixels which inevitably sacrifices spatial resolution. To increase data acquisition, commercially available DECT scanners use either two-scan settings or costly hardware components which further reduces the clinical value of DECT. The first part of this presentation presents an algorithm for DECT with unique features of effective noise suppression without degradation of spatial resolution and minimal effect on noise power spectra. Signal variations are reduced by globally minimizing the entropy of DECT images. The method’s strengths have been demonstrated by extensive simulation, phantom, and patient studies. The second part investigates a hardware-based approach which enables DECT on a conventional CT scanner using only one CT scan. An attenuation sheet – primary modulator — is inserted into the x-ray path to modify the beam spectrum. Proof-of-concept studies were completed on a table-top x-ray CT system and show great promise for this approach to high-quality DECT imaging with single-scan data. The method can be conveniently implemented on most CT scanners, with the additional possibility of effective scatter correction.


Michael Petrongolo is a PhD candidate in Georgia Tech’s Medical Physics Program and is a member of Dr. Lei Zhu’s research group. At Georgia Tech, Michael’s research efforts have primarily focused on dual energy CT. He plans to graduate in May 2016. Before attending Georgia Tech, he studied Medical Physics at East Carolina University and obtained his Masters in 2012. His undergraduate studies were at the University of Notre Dame where he earned a BS in Mechanical Engineering and a BA in Philosophy.