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Department: | Radiology |
| Address: | 2424 Erwin Road (Hock Plaza), Suite 302 Durham, NC 27705 |
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| Phone: | Reception: (919) 684-1440 Desk: (919) 684-1442 |
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| Fax: | (919) 684-1492 | |
| Email: | Send Email | |
| Web: | http://deckard.duhs.duke.edu/~ajk17/ |
My research focuses on developing an innovative imaging modality - Neutron Stimulated Emission Computed Tomography (NSECT), that uses inelastic scattering through fast neutrons to generate tomographic images of the body's element composition. Such information is vital in diagnosing a variety of disorders ranging from iron and copper overload in the liver to several cancers. Specifically, there are two ongoing projects:
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.
Peer Reviewed Publications
Floyd CE, Bender JE, Sharma AC, Kapadia AJ, Xia JQ, Harrawood BP, Tourassi GD, Lo JY, Crowell AS, and Howell CR, "Introduction to neutron stimulated emission computed tomography," Physics in Medicine and Biology, vol. 51, pp. 3375-3390, 2006. (Abstract selected for the “Yearbook of Nuclear Medicine”.)
Floyd CE, Sharma AC, Bender JE, Kapadia AJ, Xia JQ, Harrawood BP, Tourassi GD, Lo JY, Kiser MR, Crowell AS, Pedroni RS, Macri RA, Tajima S, and Howell CR, "Neutron Stimulated Emission Computed Tomography: Background Corrections," Nuclear Instruments and Methods in Physics Research Section B, vol. 254, pp. 329 - 336, 2007.
Sharma AC, Tourassi GD, Kapadia AJ, Harrawood BP, Crowell AS, Kiser MR, Howell CR, and Floyd CE, "Design and Development of a High-Energy Gamma Camera for use with NSECT Imaging: Feasibility for Breast Imaging," IEEE Transactions on Nuclear Science, vol. 54, pp. 1498 - 1505, 2007.
Sharma AC, Harrawood BP, Bender JE, Tourassi GD, Kapadia AJ, “Neutron Stimulated Emission Computed Tomography: a Monte Carlo simulation approach,” Physics in Medicine and Biology, vol. 52, pp. 6117-31, 2007. (Featured in “Physics in Medicine and Biology Highlights of 2007”)
Bender JE, Kapadia AJ, Sharma AC, Tourassi GD, Harrawood BP, and Floyd CE, "Breast cancer detection using Neutron Stimulated Emission Computed Tomography: prominent elements and dose requirements," Medical Physics, vol. 34, pp. 3866-3871, 2007.
Kapadia AJ, Sharma AC, Bender JE, Tourassi GD, Howell CR, Crowell AS, Kiser MR, Harrawood BP, Pedroni RS, and Floyd CE, "Neutron Stimulated Emission Computed Tomography for Diagnosis of Breast Cancer," IEEE Transactions on Nuclear Science, vol. 55(1), pp .501 – 509, 2008.
Floyd CE, Kapadia AJ, Bender JE, Sharma AC, Xia JQ, Harrawood BP, Tourassi GD, Lo JY, Crowell AS, and Howell CR, "Neutron Stimulated Emission Computed Tomography of a Multi-Element Phantom," Physics in Medicine and Biology, vol 53. pp 2313-2326, 2008.
Kapadia AJ, Tourassi GD, Sharma AC, Crowell AS, Kiser MR, Howell CR, “Experimental detection of iron overload in liver through neutron stimulated emission spectroscopy,” Physics in Medicine and Biology, vol 53, pp 2633-2649, 2008.
Conference Proceedings
Floyd CE, Howell CR, Harrawood BP, Crowell AS, Kapadia AJ, Macri R, Xia JQ, Pedroni R, Bowsher J, Kiser MR, Tourassi GD, Tornow W, and Walter R, "Neutron Stimulated Emission Computed Tomography of Stable Isotopes," Proceedings of SPIE Medical Imaging 2004, vol. 5368, pp. 248-254.
Kapadia AJ and Floyd CE, "An attenuation correction technique to correct for neutron and gamma attenuation in the reconstructed image of a neutron stimulated emission computed tomography (NSECT) system," Proceedings of SPIE Medical Imaging 2005, vol. 5745, pp. 737-743.
Kapadia AJ, Floyd CE, Bender JE, Howell CR, Crowell AS, and Kiser MR, "Non-invasive quantification of iron 56-Fe in beef liver using neutron stimulated emission computed tomography," Proceedings of IEEE Nuclear Science Symposium, Medical Imaging Conference 2005, vol. 4, pp. 2232-2234.
Floyd CE, Bender JE, Harrawood BP, Sharma AC, Kapadia AJ, Tourassi GD, Lo JY, and Howell CR, "Breast cancer diagnosis using Neutron Stimulated Emission Computed Tomography: Dose and Count requirements," Proceedings of SPIE Symposium on Medical Imaging 2006, vol. 6142, pp. 597-603.
Bender JE, Floyd CE, Harrawood BP, Kapadia AJ, Sharma AC, and Jesneck JL, "The effect of detector resolution for quantitative analysis of neutron stimulated emission computed tomography," Proceedings of SPIE Medical Imaging 2006, vol. 6142, pp. 1597-1605.
Kapadia AJ, Sharma AC, Tourassi GD, Bender JE, Howell CR, Crowell AS, Kiser MR, and Floyd CE, "Neutron Spectroscopy of Mouse Using Neutron Stimulated Emission Computed Tomography (NSECT)," Proceedings of IEEE Nuclear Science Symposium, Medical Imaging Conference 2006, vol. 6, pp. 3546-3548.
Kapadia AJ, Sharma AC, Tourassi GD, Bender JE, Howell CR, Crowell AS, Kiser MR, and Floyd CE, "Neutron Stimulated Emission Computed Tomography (NSECT) for Early Detection of Breast Cancer," Proceedings of IEEE Nuclear Science Symposium, Medical Imaging Conference 2006, vol. 6, pp. 3928-3931.
Kapadia AJ, Sharma AC, Tourassi GD, Bender JE, Howell CR, Crowell AS, Kiser MR, and Floyd CE, "Non-Invasive Estimation of Potassium (39K) in Bovine Liver Using Neutron Stimulated Emission Computed Tomography (NSECT)," Proceedings of IEEE Nuclear Science Symposium, Medical Imaging Conference 2006, vol. 4, pp. 2076-2078.
Sharma AC, Tourassi GD, Kapadia AJ, Harrawood BP, Bender JE, Crowell AS, Kiser MR, Howell CR, and Floyd CE, "Design and Construction of a Prototype Rotation Modulation Collimator for near-Field High-Energy Spectroscopic Gamma Imaging," Proceedings of IEEE Nuclear Science Symposium, Medical Imaging Conference 2006, vol. 4, pp. 2021-2024.
Sharma AC, Tourassi GD, Kapadia AJ, Bender JE, Xia JQ, Harrawood BP, Crowell AS, Kiser MR, Howell CR, and Floyd CE, "Development of a High-Energy Gamma Camera for Use with NSECT Imaging of the Breast," Proceedings of IEEE Nuclear Science Symposium, Medical Imaging Conference 2006, vol. 6, pp. 3925-3927.
Sharma AC, Floyd CE, Harrawood BP, Tourassi GD, Kapadia AJ, Bender JE, Lo JY, and Howell CR, "Rotating slat collimator design for high-energy near-field imaging," Proceedings of SPIE Medical Imaging 2006, vol. 6142, pp. 405-413.
Sharma AC, Tourassi GD, Kapadia AJ, Crowell AS, Kiser MR, Hutcheson A, Harrawood BP, Howell CR, Floyd CE. “Elemental Spectrum of a Mouse Obtained via Neutron Stimulation.” Proceedings of the 2007 SPIE Symposium on Medical Imaging, vol. 6510, 65100K, 2007.
Kapadia AJ, Harrawood BP, Tourassi GD, “ A Geant4 Simulation for Iron Overload Detection using NSECT,” Proceedings of IEEE Nuclear Science Symposium, Medical Imaging Conference 2007, vol. 6, pp 4604–4607.
Sharma AC, Kapadia AJ, Harrawood BP, Tourassi GD, "Optimization of a Rotating Modulation Collimator for NSECT imaging," Proceedings of the 2007 SPIE Symposium on Medical Imaging, vol. 6510, 65100K.
Kapadia AJ, Harrawood BP, Tourassi GD, “GEANT4 simulation of NSECT for detection of iron overload in the liver,” Proceedings of the 2008 SPIE Symposium on Medical Imaging, vol. 6913, pp. 691309.
Kapadia AJ, Harrawood BP, Tourassi GD, “Validation of a GEANT4 simulation of neutron stimulated emission computed tomography,” Proceedings of the 2008 SPIE Symposium on Medical Imaging, vol. 6913, pp. 69133H.
Kapadia AJ, Gallmeier FX, Iverson EB, Ferguson PD, “Detection of Iron Overload with the ORNL Spallation Neutron Source: an MCNPX Simulation Study”, Proceedings of IEEE Nuclear Science Symposium, Medical Imaging Conference 2008.
Kapadia AJ, Agasthya GA, Tourassi GD, “Detection of Iron Overload through Neutron Stimulated Emission Computed Tomography: A Sensitivity Analysis Study”, Proceedings of the SPIE Symposium on Medical Imaging, 2009.
Ph.D. Dissertation
Kapadia AJ, "Accuracy and Patient Dose in Neutron Stimulated Emission Computed Tomography for Diagnosis of Liver Iron Overload: Simulations in GEANT4", Duke University, Department of Biomedical Engineering , 2007. (Abstract)
Summary of Qualifications
- Doctoral and bachelors degrees in Biomedical Engineering.
- Knowledge of image reconstruction techniques, attenuation correction and high-energy nuclear physics.
- Extensive training and expertise in Neutron Imaging and Monte-Carlo Simulations.
- Developed new imaging modality – Neutron Stimulated Emission Computed Tomography.
Education
- Duke University, Durham NC Ph.D. in Biomedical Engineering (September 2007)
- University of Mumbai, India B.E. in Biomedical Engineering (June 2001)
Awards and Honors
- Pre-doctoral Traineeship Award, U.S. Army Medical Research and Materiel Command Breast Cancer Research Program, (1 of 106 awardees from a national pool of applicants), 2006 – 2009.
- Trai Award to present research at the IEEE Nuclear Science Symposium/Medical Imaging Conference, 2005, 2006, 2007, 2008.
- Publication titled “Introduction to Neutron Stimulated Emission Computed Tomography” selected for abstraction in “Yearbook of Nuclear Medicine”.
- Graduate Fellowship, Duke University Department of Biomedical Engineering, 2003 – 2007.
- Ranked in top 2 - Graduating class of 2001 (BME) - D.J.Sanghvi College of Engineering, University of Mumbai.
Experience
Duke University, Durham, NC 2003 – 2007
Research Assistant, Department of Biomedical Engineering
- Examined behavior of neutrons in detecting trace elements in the human body to diagnose cancer.
- Developed and implemented research strategies for new imaging modality.
- Successfully applied for pre-doctoral research grant from the Department of Defense for dissertation research.
- Built and tested Monte-Carlo simulations of three-dimensional neutron imaging system in GEANT4.
- Developed attenuation correction algorithms for neutron and gamma attenuation in NSECT.
- Designed and built an innovative neutron camera to create two-dimensional images of neutron beams.
- Designed and built a tomographic gantry for NSECT scanning of a human torso and liver phantom.
- Authored or co-authored 13 scientific papers in peer-reviewed journals and proceedings.
MCNC-RDI, Durham,NC Summer 2003
Summer Internship
- Tested PZT MEMS actuators, PVDF thin films, and prototype 2D Micro-machined Ultrasound Transducers to correlate resonant peaks with device geometry.
- Optimized packaging process for Electrostatic MEMS devices for Micro-valves, in terms of assembly, electrical interconnects and sealing.
Duke University, Durham, NC 2002 – 2003
Assistant Engineer, Department of Biomedical Engineering
- Designed and milled a PCB to test the cross-talk of a 64-channel amplifier chip using PCAD.
- Designed a handle for an Ultrasound Transducer using CAD.
- Testing and troubleshooting electrical circuits and components for 3D Ultrasound Unit.
Shruti Medi-Science Pvt. Ltd. Mumbai, India 2001 – 2002
Service Engineer, Medical Equipment Division
- Provided on-site service and technical support for Defibrillators, Pacemakers, ABPM, Holter systems and Patient Monitors.
Siemens Ltd., Mumbai, India and Muscat, Oman Fall 2000
In-plant Trainee Engineer
- Assisted field service engineers with on-site service for ultrasound, ventilators, patient monitors, gamma camera, x-ray, CT & MRI units.
- Installed 24-bed ICU Patient Monitoring System at Holy Spirit Hospital, Mumbai, India.
Computer Skills
- Unix, Linux, DOS, Microsoft Windows, Mac OSX
- C++, Matlab, GEANT4, SpecTcl, PCAD, all MS-Office tools, Adobe Photoshop
Relevant Coursework
- Simulations in Medical Imaging, Radiology in Practice, Biological Imaging with Neutrons, Modern Diagnostic Imaging Systems, Computer Aided Diagnosis, Scientific Computing, Statistical Methods, Ultrasound Transducer Design, Interferometry in Bio-diagnostics, Molecular Physiology, Laser-tissue Interactions, Principles of Diagnostic Imaging, Modern Physics (Graduate).
- Biomedical Instrumentation, Image Processing, Radiology and Medical Imaging, Biomechanics, Artificial Organs and Implants, Biological Control Systems, Transducers, Biomaterials, Biology, Microprocessors, Advanced Mathematics, Electronics, Engineering Mechanics (Undergraduate).
Activities and Affiliations
- IEEE Nuclear and Plasma Sciences Society, Student Member, 2005 – Present
- SPIE – The International Society for Optical Engineering, Student Member, 2005 - Present
- Student editor, American Journal Experts – 2006, 2007
References
Available upon request