Anuj J Kapadia
Associate Professor in Radiology
1) Experimental Implementation of NSECT
Neutron spectroscopy techniques are showing significant promise in determining element concentrations in the human body. We have developed a tomographic imaging system capable of generating tomographic images of the element concentration within a body through a single non-invasive in-vivo scan. This system has been implemented using a Van-de-Graaf accelerator fast neutron source and high-purity germanium gamma detectors at the Triangle Universities Nuclear Laboratory. This setup has been used to obtain NSECT scans for several samples such as bovine liver, mouse specimens and human breast tissue. In order to extract maximum information about a target sample with the lowest possible levels of dose, it is essential to maximize the sensitivity of the scanning system. In other words, the signal to noise ratio for the experimental setup must be maximized. This project aims at increasing the sensitivity of the NSECT system by understanding the various sources of noise and implementing techniques to reduce their effect. Noise in the system may originate from several factors such as the radiative background in the scanning room, and neutron scatter off of components of the system other than the target. Some of these effects can be reduced by using Time-of-Flight background reduction, while others can be reduced by acquiring a separate sample-out scan. Post processing background reduction techniques are also being developed for removing detector efficiency dependent noise. At this point we have acquired element information from whole mouse specimens and iron-overloaded liver models made of bovine liver tissue artificially injected with iron. Tomographic images have been generated from a solid iron and copper phantom. Our final goal is to implement a low-dose non-invasive scanning system for diagnosis of iron overload and breast cancer.
2) Monte-Carlo simulations in GEANT4
For each tomographic scan of a sample using NSECT, there are several acquisition parameters that can be varied. These parameters can broadly be classified into three categories: (i) Neutron Beam parameters: neutron flux, energy and beam width, (ii) Detector parameters: detector type, size, efficiency and location; (iii) Scanning Geometry: spatial and angular sampling rates. Due to the enormous number of combinations possible using these parameters, it is not feasible to investigate the effects of each parameter on the reconstructed image using a real neutron beam in the limited beam time available. A feasible alternative to this is to use Monte-Carlo simulations to reproduce the entire experiment in a virtual world. The effect of each individual parameter can then be studied using only computer processing time and resources. We use the high energy physics Monte-Carlo software package GEANT4, developed by CERN, which incorporates numerous tools required for building particle sources and detectors, and tracking particle interactions within them. The simulations built so far include the neutron source, HPGE and BGO gamma detectors, and several target materials such as iron, liver and breast tissue.
Viana, R. S., et al. “3D element imaging using NSECT for the detection of renal cancer: a simulation study in MCNP..” Phys Med Biol, vol. 58, no. 17, Sept. 2013, pp. 5867–83. Pubmed, doi:10.1088/0031-9155/58/17/5867. Full Text
Kapadia, A. J., et al. “Monte-Carlo simulations of a coded-aperture X-ray scatter imaging system for molecular imaging.” Progress in Biomedical Optics and Imaging Proceedings of Spie, vol. 8668, June 2013. Scopus, doi:10.1117/12.2008484. Full Text
Rhee, D. J., et al. “Neutron stimulated emission computed tomography for brain cancer imaging.” Ieee Nuclear Science Symposium Conference Record, Jan. 2013. Scopus, doi:10.1109/NSSMIC.2013.6829159. Full Text
Magana, Q., et al. “Automated hemochromatosis spectra analysis using neutron stimulated emission tomography.” Ieee Nuclear Science Symposium Conference Record, Dec. 2012, pp. 2497–500. Scopus, doi:10.1109/NSSMIC.2012.6551570. Full Text
Lakshmanan, M. N., et al. “Nuclear resonance fluorescence (NRF) in GEANT4: Development, validation, and testing.” Ieee Nuclear Science Symposium Conference Record, Dec. 2012, pp. 1731–34. Scopus, doi:10.1109/NSSMIC.2012.6551406. Full Text
Lakshmanan, M. N., and A. J. Kapadia. “Quantitative assessment of lesion detection accuracy, resolution, and reconstruction algorithms in neutron stimulated emission computed tomography..” Ieee Transactions on Medical Imaging, vol. 31, no. 7, July 2012, pp. 1426–35.
Lakshmanan, Manu N., and Anuj J. Kapadia. “Quantitative assessment of lesion detection accuracy, resolution, and reconstruction algorithms in neutron stimulated emission computed tomography..” Ieee Transactions on Medical Imaging, vol. 31, no. 7, July 2012, pp. 1426–35. Epmc, doi:10.1109/tmi.2012.2192134. Full Text
Kapadia, A., et al. “SU-E-T-108: 3D Measurement of Neutron Dose from a Novel Neutron Imaging Technique..” Med Phys, vol. 39, no. 6Part11, June 2012. Pubmed, doi:10.1118/1.4735166. Full Text
Kapadia, A., et al. “SU-E-I-77: X-Ray Coherent Scatter Diffraction Pattern Modeling in GEANT4..” Med Phys, vol. 39, no. 6Part5, June 2012, pp. 3642–43. Pubmed, doi:10.1118/1.4734794. Full Text
Agasthya, G. A., et al. “Sensitivity analysis for liver iron measurement through neutron stimulated emission computed tomography: a Monte Carlo study in GEANT4..” Phys Med Biol, vol. 57, no. 1, Jan. 2012, pp. 113–26. Pubmed, doi:10.1088/0031-9155/57/1/113. Full Text
Wilson, J. M., et al. “Empowering Future Clinical Leaders: Professionalism in Medical Physics Graduate Education.” Medical Physics, vol. 44, no. 6, WILEY, 2017, pp. 3067–3067.
Fu, W., et al. “Uncertainties in Convolution-Based Organ Dose Estimation in TubeCurrent Modulated CT.” Medical Physics, vol. 44, no. 6, WILEY, 2017, pp. 3301–3301.
Hoye, J., et al. “A Smartphone Application for Organ Dose Estimation in CT, Tomosynthesis, and Radiography.” Medical Physics, vol. 44, no. 6, WILEY, 2017, pp. 3022–3022.
Hoye, J., et al. “An atlas-based organ dose estimator for tomosynthesis and radiography.” Progress in Biomedical Optics and Imaging Proceedings of Spie, vol. 10132, 2017. Scopus, doi:10.1117/12.2255583. Full Text
Spencer, J. R., et al. “Coded aperture coherent scatter spectral imaging for assessment of breast cancers: An ex-vivo demonstration.” Progress in Biomedical Optics and Imaging Proceedings of Spie, vol. 10132, 2017. Scopus, doi:10.1117/12.2253975. Full Text
Fu, W., et al. “Estimation of breast dose reduction potential for organ-based tube current modulated CT with wide dose reduction arc.” Progress in Biomedical Optics and Imaging Proceedings of Spie, vol. 10132, 2017. Scopus, doi:10.1117/12.2255797. Full Text
Abadi, E., et al. “Airways, vasculature, and interstitial tissue: Anatomically informed computational modeling of human lungs for virtual clinical trials.” Progress in Biomedical Optics and Imaging Proceedings of Spie, vol. 10132, 2017. Scopus, doi:10.1117/12.2254739. Full Text
Albanese, K., et al. “TH-AB-209-12: Tissue Equivalent Phantom with Excised Human Tissue for Assessing Clinical Capabilities of Coherent Scatter Imaging Applications.” Medical Physics, vol. 43, no. 6Part44, Wiley, 2016, pp. 3866–3866. Crossref, doi:10.1118/1.4958103. Full Text
Fong, G., and A. Kapadia. “SU-G-IeP4-04: DD-Neutron Source Collimation for Neutron Stimulated Emission Computed Tomography: A Monte Carlo Simulation Study.” Medical Physics, vol. 43, no. 6Part27, Wiley, 2016, pp. 3678–3678. Crossref, doi:10.1118/1.4957099. Full Text
Morris, R., et al. “SU-F-I-53: Coded Aperture Coherent Scatter Spectral Imaging of the Breast: A Monte Carlo Evaluation of Absorbed Dose.” Medical Physics, vol. 43, no. 6Part8, Wiley, 2016, pp. 3398–99. Crossref, doi:10.1118/1.4955881. Full Text