Expertise within the Medical Physics and Quantitative Imaging lab includes experimental diagnostic medical physics, physical and perceptual evaluation of image quality, radiation dosimetry, computational methods (Monte Carlo and analytical), image reconstruction and characterization of the imaging performance of nanoscale contrast agents for the early detection of cancer. One area of focus is on creating and optimizing new methods of imaging the breast that take advantage of the introduction of digital detectors for mammography. Among other areas of research emphasis are 4D CT for cardiovascular imaging and image-guided radiation therapy, motion compensated image reconstruction, optimization of image acquisition to minimize radiation dose, and tomographic and contrast-enhanced breast imaging techniques. The lab environment is dynamic, and new ideas and risk-taking in research are highly encouraged.
The laboratory is located in the new building of the Winship Cancer Institute of Emory University in close proximity to the breast imaging section and the outpatient imaging center of the Emory Clinic. The location and physical layout of the lab is ideal for research in medical imaging. The laboratory is equipped with a clinical prototype digital mammography system and a experimental digital radiography system. A dedicated viewing room is also available with two mammographic five megapixel flat panel displays. Other resources include several high performance workstations, desktop computers, computational and imaging software such as IDL, ImagePro, Geant4, etc., and electronic testing equipment. The lab communicates with a 1,024 processor high performance cluster computing system, a shared resource at Emory University. An investigational device (non-FDA approved) dedicated breast CT system will be operational in the laboratory in mid-2008.
Breast Cancer Chemotherapy Monitoring with Dedicated Breast Computed Tomography
Principal Investigators: Carl D'Orsi, MD
Ioannis Sechopoulos, PhD
The goal of the proposal is to use a dedicated breast CT system to closely monitor the changes in size and blood flow of breast tumors in patients undergoing neoadjuvant chemotherapy. For this, a prototype dedicated breast CT system, to be installed in June in the Breast Imaging Center, will be used. This system will be only the second prototype clinical system of its kind in the world. Its isotropic high resolution, high contrast, low dose capabilities bring about a wide variety of new approaches to breast cancer detection and treatment that will be investigated here at Emory.
The ultimate aim of this work, for which this grant is just an initial first step, is to be able to adjust the chemotherapy treatment according to imaging-based monitoring of tumor response. Today most patients undergoing neoadjuvant chemotherapy are treated with a certain pre-determined number of treatment cycles, each separated by a fixed amount of time, with varying results due to each individual tumor’s response to the chemotherapeutic drugs. Breast CT monitoring could result in a personalized therapy regimen, in which non-responders are identified in a short period of time so that other treatment options are sought. Further, treatment can be terminated early for complete responders, for whom the additional cycles do not provide any additional benefits.Analytical and computational approaches for the development and optimization of digital tomosynthesis imaging of the breast
Purpose: The introduction of breast tomosynthesis imaging in the clinical environment requires comprehensive optimization studies to maximize image quality. Our group is using advanced simulation methods and the computing power available at Emory University to study how to obtain the highest quality reconstructions while limiting the radiation dose to the breast.
Investigation of nanoscale contrast agents for the early detection of breast cancer
(Collaboration with Georgia Institute of Technology)
Purpose: The study is aimed at the adaptation of nanoparticle-based contrast agents for increasing the sensitivity of breast cancer detection, for delineating tumor margins, and to determine effectiveness of therapy.
Computational and experimental approaches for radiation dosimetry in mammography, tomographic breast imaging and other x-ray imaging applications
Purpose: The emergence of new x-ray imaging techniques through digital technologies, particularly those that require multiple views for tomographic imaging prompts careful assessment of the radiation dose to target and other tissues. Our group has developed a detailed methodology for the estimation of dose from tomosynthesis and computed tomography of the breast.
Analytical, computational and experimental approaches for the development of dedicated computed tomography of the breast
Purpose: Our laboratory is one of the few in the world working on the adaptation of computed tomography technology for 3D imaging of the breast. Clinical feasibility trials are planned to start in early 2008.
2013 SEAAPM Best Paper Award
Dr. Sechopoulos received the 2013 SEAAPM Best Paper Award for his paper "Characterization of the homogeneous tissue mixture approximation in breast imaging dosimetry." His paper received the highest score from all of the reviewers on the Awards and Nominations Committee. This is Dr. Sechopoulos second time in a row receiving this award.
Image Quality Improvement and Breast Compression Reduction in Breast Tomosynthesis
Principal Investigator:Ioannis Sechopoulos, Ph.D.
Co-Investigators: Carl J. D'Orsi, M.D., Baowei Fei, Ph.D., Mary Newell, M.D.
Significance: The objective of this research project is to develop and test new image acquisition and processing techniques that will allow for the acquisition of breast tomosynthesis images with a substantial reduction in the amount of breast compression used with no loss in image quality or increase in radiation dose. For this, we will (1) develop a method to reduce the impact of x-ray scatter on image quality; (2) develop new image acquisition techniques for reduced compression tomosynthesis that result in the same radiation dose and image noise levels as standard tomosynthesis; (3) compare the image quality between standard tomosynthesis and reduced compression tomosynthesis performed with the techniques developed in this project.
Program Director for Physics Education
As Assistant Program Director for Physics Education, Dr. Ioannis Sechopoulos will provide oversight and coordination of the physics education for our Diagnostic Radiology Residency program in close collaboration with Dr. Mark Mullins, Program Director. This includes the introductory radiologic physics course, refresher course, laboratory experiences and web-based physics modules.
American Association of Physicists in Medicine
Ioannis Sechopoulos, PhD
Dr. Sechopoulos has been appointed to the Editorial Board of the journal Medical Physics, published by the American Association of Physicists in Medicine. During his three-year term beginning on January 1, 2012, Dr. Sechopoulos will serve as Associate Editor. He will review manuscripts submitted to the journal, participate in editorial board decisions and provide advice on disputed or appealed manuscript decisions.
Radiology - Editor's Recognition Awards for Reviewing with Speicial Distinction
Ioannis Sechopoulos, PhD, Assistant Professor of Radiology
Each year the publication Radiology recognizes reviewers who have exhibited a high quality of their prompt, detailed and scholarly reviews. The 2010 list of awardees acknowledges Drs. D'Orsi and Sechopoulos with "Special Distinction" for their contributions.
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Farrington Daniels Award
Ioannis Sechopoulos, PhD, Assistant Professor of Radiology
The American Association of Physicists in Medicine (AAPM) has selected Dr. Sechopoulos as the recipient of the Farrington Daniels Award for one of the best papers on radiation dosimetry. The featured paper was published by Medical Physics in 2007: "Computation of the glandular radiation dose in digital tomosynthesis of the breast". (Medical Physics 34, Number 1/221, 2007)
Yang Y and Tang X. “The second-order differential phase contrast and its retrieval for imaging with x-ray Talbot interferometry” Med. Phys, 2013, 39(12): 7237-53.
Sechopoulos, I., “A review of reast tomosynthesis. Part I. The image acquisition process.” Medical Physics, 2013. 40(1): p. 014301.
Sechopoulos, I., “A review of breast tomosynthesis. Part II. Image reconstruction, processing and analysis, and advanced
applications”. Medical Physics, 2013. 40(1): p. 014302.
Yang X, Wu S, Sechopoulos I, and Fei B. Cupping artifact correction and automated classification for high-resolution dedicated breast CT images. Med. Phys. 2012. 39, 6397.
Tang S and Tang X. Statistical CT noise reduction with multiscale decomposition and penalized weighted least squares in the projection domain. Med. Phys., 2012, 39(9): 5498-512.
Tang X, Yang Y and Tang S. Characterization of imaging performance in differential phase contrast CT compared with the conventional CT – Spectrum of noise equivalent quanta NEQ(k). Med. Phys., 39(7): 4467-82, 2012
Feng SS, Sechopoulos I. A software-based x-ray scatter correction method for breast tomosynthesis. Medical Physics 2011, Vol. 38, Issue 12, page 6643.
Chung J, Nagy JG, Sechopoulos I. Numerical Algorithms for Polyenergetic Digital Breast Tomosynthesis Reconstruction. SIAM J. Imaging Sci. 3, 133 (2010), DOI:10.1137/090749633.
Karathanasis E, Chan L, Karumbaiah L, McNeeley K, D'Orsi CJ, Ananth, Annapragada V, Sechopoulos I, et al. 2009. Tumor Vascular Permeability to a Nanoprobe Correlates to Tumor-Specific Expression Levels of Angiogenic Markers. PLoS ONE 4(6): e5843. doi:10.1371/journal.pone.0005843.
Sechopoulos I, Ghetti C. Optimization of the acquisition geometry in digital tomosynthesis of the breast. Med. Phys. 2009 April 36;4:1199-1207.
Sechopoulos I, D'Orsi CJ. Glandular radiation dose in tomosynthesis of the breast using tungsten targets. Journal of Applied Clinical Medical Physics 2008; 9(4):161-171.
Karathanasis E, Chan L, Balusu SR, D'Orsi CJ, Annapragada AV, Sechopoulos I, Bellamkonda RV. Multifunctional nanocarriers for mammographic quantification of tumor dosing and prognosis of breast cancer therapy. Biomaterials. 2008 Sep 22.
Sechopoulos I, Suryanarayanan S, Vedantham S, D'Orsi CJ, Karellas A. Monte Carlo and Phantom Study of the Radiation Dose to the Body from Dedicated CT of the Breast Radiology 2008; 10.1148/radiol.2471071080.
Sechopoulos I, Suryanarayanan S, Vedantham S, D'Orsi CJ, Karellas A. Radiation Dose to Organs and Tissues from Mammography: Monte Carlo and Phantom Study. Radiology 2008; 246: 434-443.
The article Radiation Dose to Organs and Tissues from Mammography: Monte Carlo and Phantom Study inspired HeathNewsDigest.com to post an article in the Women's Health section, increasing radiation education as it applies to the overall amount of radiation mammograms deliver to the entire body and to the fetus when pregnant women undergo mammography. The article goes on to explain how a three-dimensional virtual human and Emory's new High Performance Computing Cluster aided the collection of data.
To view this article click here.
Sechopoulos I, Suryanarayanan S, Vedantham S, D'Orsi CJ, Karellas A. Computation of the glandular radiation dose in digital tomosynthesis of the breast. Medical Physics 2007; 34: 221-232.
Sechopoulos I, Suryanarayanan S, Vedantham S, D'Orsi CJ, Karellas A. Scatter radiation in digital tomosynthesis of the breast. Medical Physics 2007; 34: 564-576.
Jessica Paulishen
Research Project Coordinator
Phone: 404 712-1869
E-mail: jpauli2@emory.edu