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Dive into the research topics where Ram Naidu is active.

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Featured researches published by Ram Naidu.


sensors applications symposium | 2007

Dual Energy Volumetric X-ray Tomographic Sensor for Luggage Screening

Zhengrong Ying; Ram Naidu; Kyle Guilbert; David Schafer; Carl R. Crawford

Various imaging sensors have been used for luggage screening for explosive detection. Recent developments in dual energy X-ray volumetric computed tomography (CT) have demonstrated its advantages over other imaging sensors for luggage screening. These advantages include higher performance in automatic explosive detection, effectiveness for weapon detection, superior visualization capabilities, and automatic visual cueing for on-screen threat resolution. In this paper, we describe the performance of one such X-ray sensor using our transportation security administration (TSA) certified dual energy volumetric CT for explosive detection.


IEEE Transactions on Medical Imaging | 2008

Variable Pitch Reconstruction Using John's Equation

Ba¿ak Ülker Karbeyaz; Ram Naidu; Zhengrong Ying; Sergey Simanovsky; Matthew Hirsch; David Schafer; Carl R. Crawford

We present an algorithm to reconstruct helical cone beam computed tomography (CT) data acquired at variable pitch. The algorithm extracts a halfscan segment of projections using an extended version of the advanced single slice rebinning (ASSR) algorithm. ASSR rebins constant pitch cone beam data to fan beam projections that approximately lie on a plane that is tilted to optimally fit the source helix. For variable pitch, the error between the tilted plane chosen by ASSR and the source helix increases, resulting in increased image artifacts. To reduce the artifacts, we choose a reconstruction plane, which is tilted and shifted relative to the source trajectory. We then correct rebinned fan beam data using Johns equation to virtually move the source into the tilted and shifted reconstruction plane. Results obtained from simulated phantom images and scanner images demonstrate the applicability of the proposed algorithm.


international symposium on biomedical imaging | 2009

A correction framework for non-ideal source switching in dual energy CT scanner

Julia Pavlovich; Andrew Litvin; Aleksander Roshi; Sergey Simanovsky; Ram Naidu

Dual energy CT requires two measurements of object attenuation at two different energies. Two measurements can be obtained by switching between two sources operating at two different spectra. Non-ideal source switching causes data mixing which produces image artifacts. We propose a framework to correct data to prevent such image artifacts using a recursive view mixing model. A nonlinear optimization approach estimates the model parameters using data from a calibration procedure based on a symmetry metric. Results from a commercial dual energy CT scanner demonstrate the effectiveness of the proposed approach.


Archive | 2002

Method of and system for reducing metal artifacts in images generated by x-ray scanning devices

Ram Naidu; Ibrahim M. Bechwati; Seemee S. Karimi; Sergey Simanovsky; Carl R. Crawford


Journal of X-ray Science and Technology | 2006

Dual energy computed tomography for explosive detection

Zhengrong Ying; Ram Naidu; Carl R. Crawford


Archive | 2004

Method of and system for computing effective atomic number images in multi-energy computed tomography

Zhengrong Ying; Ram Naidu; Sergey Simanovsky; Carl R. Crawford


Archive | 2004

Method of and system for adaptive scatter correction in multi-energy computed tomography

Zhengrong Ying; Ram Naidu; Sergey Simanovsky; Carl R. Crawford


Archive | 2003

Decomposition of multi-energy scan projections using multi-step fitting

Ram Naidu; Ibrahim M. Bechwati; Carl R. Crawford


Archive | 2004

Method of and system for X-ray spectral correction in multi-energy computed tomography

Ram Naidu; Zhengrong Ying; Chitra Subramanian; Sergey Simanovsky; Carl R. Crawford


Archive | 2004

Method of and system for stabilizing high voltage power supply voltages in multi-energy computed tomography

Ram Naidu; Zhengrong Ying; Carl R. Crawford

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Matthew Hirsch

Massachusetts Institute of Technology

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