Jeffrey H. Siewerdsen | |
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Born | 1969 (age 54–55) |
Alma mater | University of Michigan University of Minnesota |
Known for | Image-guided surgery |
Awards | Moses and Sylvia Greenfield Award (2015) Sylvia Fedoruk Award (2005) Farrington-Daniels Award (2002) Sylvia Sorkin Greenfield Award (2001) |
Scientific career | |
Institutions | Johns Hopkins University University of Toronto William Beaumont Hospital University of Michigan University of Minnesota |
Thesis | Signal, Noise, and Detective Quantum Efficiency of a-Si:H Flat-Panel Imagers (1998) |
Doctoral advisor | Larry E. Antonuk |
Website | The I-STAR Lab The Carnegie Center for Surgical Innovation |
Jeffrey Harold Siewerdsen (born 1969) is an American physicist and biomedical engineer who is a Professor of Imaging Physics at The University of Texas MD Anderson Cancer Center as well as Biomedical Engineering, Computer Science, Radiology, and Neurosurgery at Johns Hopkins University.He is among the original inventors of cone-beam CT-guided radiotherapy [1] as well as weight-bearing cone-beam CT [2] [3] for musculoskeletal radiology and orthopedic surgery. His work also includes the early development of flat-panel detectors on mobile C-arms for intraoperative cone-beam CT in image-guided surgery. [4] He developed early models for the signal and noise performance of flat-panel detectors [5] and later extended such analysis to dual-energy imaging [6] and 3D imaging performance in cone-beam CT. [7] He founded the ISTAR Lab (Imaging for Surgery, Therapy, and Radiology) in the Department of Biomedical Engineering, the Carnegie Center for Surgical Innovation at Johns Hopkins Hospital, and the Surgical Data Science Program at the Institute for Data Science in Oncology at The University of Texas MD Anderson Cancer Center.
Jeffrey Siewerdsen did his undergraduate studies at the University of Minnesota in Minneapolis, MN, where he received his Bachelor of Arts degree in Physics and Astrophysics with a minor in Japanese in 1992. His undergraduate research experience included construction and testing of particle detectors for the Soudan 2 proton decay project.
Siewerdsen began graduate studies at the University of Michigan in Ann Arbor, MI, in 1992, working initially in high-energy physics (D0 experiment) under supervision of Professor Homer Neal and earning his Master of Science degree in Physics in 1994.
Siewerdsen's doctoral research involved early development of amorphous silicon Flat panel detector for medical x-ray imaging under the supervision of Professor Larry E. Antonuk. Siewerdsen's work focused on the development of early flat-panel detector systems for diagnostic radiography, fluoroscopy, and mammography as well as megavoltage portal imaging for guidance of radiation therapy. His doctoral dissertation [8] established mathematical models for the signal-to-noise properties (specifically, the modulation transfer function, noise-power spectrum, and detective quantum efficiency) of flat-panel x-ray detectors. His Ph.D. thesis was awarded the Kent M. Terwilliger Prize for Best Doctoral Dissertation in Physics, 1998.
Siewerdsen conducted post-graduate research beginning in 1998 as a Research Scientist at William Beaumont Hospital in Royal Oak, MI, with Dr. David Jaffray and Dr. John Wong on the topic of cone beam computed tomography (CBCT) for image-guided radiation therapy (IGRT). [9] [10] The Beaumont team produced the first IGRT system for CBCT, beginning with laboratory studies to investigate image quality characteristics, [11] and translating to clinical studies for guidance of prostate cancer therapy. [12]
Siewerdsen joined the Ontario Cancer Institute and University of Toronto Department of Medical Biophysics as a Scientist and Assistant Professor, respectively, in 2002, and subsequently as Senior Scientist and Associate Professor in 2007. Research in his laboratory focused on image-guided surgery, new imaging methods such as dual-energy imaging, and image registration. His work involved the development of early systems for cone beam computed tomography (CBCT) with a flat-panel detector on mobile C-arms for image-guided surgery [13] and translated the first such systems to clinical studies in image-guided Otolaryngology–Head and Neck Surgery [14] [15] [16] with Dr. Jonathan Irish. He also collaborated closely with Dr. Kristy Brock on deformable image registration using the Demons algorithm [17] [18] and with Dr. Narinder Paul on development of dual-energy chest radiography systems for detection of early stage lung cancer. [19] [20]
His research also extended cascaded systems models [21] for x-ray imaging performance to describe 3D imaging performance in CBCT [22] [23] and helped to establish mathematical methods for imaging system optimization according to the imaging task. [24] Siewerdsen joined Johns Hopkins Biomedical Engineering as an Associate Professor in 2009 and subsequently as a Professor in 2012, with cross-appointment in Computer Science, Radiology, and Neurosurgery. He founded the I-STAR Lab (Imaging for Surgery, Therapy, and Radiology) [25] as a collaborative research endeavor bridging biomedical engineering with clinical collaborators at Johns Hopkins Hospital. In 2015, he established the Carnegie Center for Surgical Innovation in the Johns Hopkins School of Medicine. He was also a John C. Malone Professor in Computer Science and Member of the Malone Center for Engineering in Healthcare. Research in Siewerdsen's laboratory includes: mathematical modeling / imaging science of digital x-ray, [26] dual-energy imaging, [27] cone beam computed tomography (CBCT), [28] and computed tomography (CT) systems; [29] image-guided surgery; [30] [31] multi-modality medical image registration; [32] [33] [34] [35] new imaging systems for musculoskeletal radiology and orthopedic surgery; [36] [37] and clinical research collaborations in robot-assisted surgery and data science related to medical imaging.
In 2022, Siewerdsen joined The University of Texas MD Anderson Cancer as a Professor Imaging Physics, Radiation Physics, and Neurosurgery, where he directs the Surgical Data Science Program in the Institute for Data Science in Oncology.
Notable scientific contributions from Siewerdsen's work include:
A computed tomography scan is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers or radiology technologists.
The Hounsfield scale, named after Sir Godfrey Hounsfield, is a quantitative scale for describing radiodensity. It is frequently used in CT scans, where its value is also termed CT number.
Tomographic reconstruction is a type of multidimensional inverse problem where the challenge is to yield an estimate of a specific system from a finite number of projections. The mathematical basis for tomographic imaging was laid down by Johann Radon. A notable example of applications is the reconstruction of computed tomography (CT) where cross-sectional images of patients are obtained in non-invasive manner. Recent developments have seen the Radon transform and its inverse used for tasks related to realistic object insertion required for testing and evaluating computed tomography use in airport security.
In radiography, X-ray microtomography uses X-rays to create cross-sections of a physical object that can be used to recreate a virtual model without destroying the original object. It is similar to tomography and X-ray computed tomography. The prefix micro- is used to indicate that the pixel sizes of the cross-sections are in the micrometre range. These pixel sizes have also resulted in creation of its synonyms high-resolution X-ray tomography, micro-computed tomography, and similar terms. Sometimes the terms high-resolution computed tomography (HRCT) and micro-CT are differentiated, but in other cases the term high-resolution micro-CT is used. Virtually all tomography today is computed tomography.
David A. Jaffray is a Canadian medical physicist and Senior Scientist in the Division of Biophysics and Bioimaging at the Ontario Cancer Institute. He is also a professor and Vice Chair in the University of Toronto's Department of Radiation Oncology. He is the inventor, together with John Wong and Jeffrey Siewerdsen, of on-line volumetric kv-imaging guidance system for radiation therapy.
Tomotherapy is a type of radiation therapy treatment machine. In tomotherapy a thin radiation beam is modulated as it rotates around the patient, while they are moved through the bore of the machine. The name comes from the use of a strip-shaped beam, so that only one “slice” of the target is exposed at any one time by the radiation. The external appearance of the system and movement of the radiation source and patient can be considered analogous to a CT scanner, which uses lower doses of radiation for imaging. Like a conventional machine used for X-ray external beam radiotherapy, a linear accelerator generates the radiation beam, but the external appearance of the machine, the patient positioning, and treatment delivery is different. Conventional linacs do not work on a slice-by-slice basis but typically have a large area beam which can also be resized and modulated.
Image-guided radiation therapy is the process of frequent imaging, during a course of radiation treatment, used to direct the treatment, position the patient, and compare to the pre-therapy imaging from the treatment plan. Immediately prior to, or during, a treatment fraction, the patient is localized in the treatment room in the same position as planned from the reference imaging dataset. An example of IGRT would include comparison of a cone beam computed tomography (CBCT) dataset, acquired on the treatment machine, with the computed tomography (CT) dataset from planning. IGRT would also include matching planar kilovoltage (kV) radiographs or megavoltage (MV) images with digital reconstructed radiographs (DRRs) from the planning CT.
ITK-SNAP is an interactive software application that allows users to navigate three-dimensional medical images, manually delineate anatomical regions of interest, and perform automatic image segmentation. The software was designed with the audience of clinical and basic science researchers in mind, and emphasis has been placed on having a user-friendly interface and maintaining a limited feature set to prevent feature creep. ITK-SNAP is most frequently used to work with magnetic resonance imaging (MRI), cone-beam computed tomography (CBCT) and computed tomography (CT) data sets.
Tomosynthesis, also digital tomosynthesis (DTS), is a method for performing high-resolution limited-angle tomography at radiation dose levels comparable with projectional radiography. It has been studied for a variety of clinical applications, including vascular imaging, dental imaging, orthopedic imaging, mammographic imaging, musculoskeletal imaging, and chest imaging.
The computed tomography dose index (CTDI) is a commonly used radiation exposure index in X-ray computed tomography (CT), first defined in 1981. The unit of CTDI is the gray (Gy) and it can be used in conjunction with patient size to estimate the absorbed dose. The CTDI and absorbed dose may differ by more than a factor of two for small patients such as children.
Positron emission tomography–magnetic resonance imaging (PET–MRI) is a hybrid imaging technology that incorporates magnetic resonance imaging (MRI) soft tissue morphological imaging and positron emission tomography (PET) functional imaging.
Cone beam computed tomography is a medical imaging technique consisting of X-ray computed tomography where the X-rays are divergent, forming a cone.
Phase-contrast X-ray imaging or phase-sensitive X-ray imaging is a general term for different technical methods that use information concerning changes in the phase of an X-ray beam that passes through an object in order to create its images. Standard X-ray imaging techniques like radiography or computed tomography (CT) rely on a decrease of the X-ray beam's intensity (attenuation) when traversing the sample, which can be measured directly with the assistance of an X-ray detector. However, in phase contrast X-ray imaging, the beam's phase shift caused by the sample is not measured directly, but is transformed into variations in intensity, which then can be recorded by the detector.
Cybermed Inc., located in Seoul, South Korea, has been active in the field of 3D image processing and dental software since its conception in 1998. Its U.S. counterpart, OnDemand3D Technology Inc., is currently headquartered in Irvine, California.
Proton computed tomography (pCT), or proton CT, is an imaging modality first proposed by Cormack in 1963 and initial experiment explorations identified several advantages over conventional X-ray CT (xCT). However, particle interactions such as multiple Coulomb scattering (MCS) and (in)elastic nuclear scattering events deflect the proton trajectory, resulting in nonlinear paths which can only be approximated via statistical assumptions, leading to lower spatial resolution than X-ray tomography. Further experiments were largely abandoned until the advent of proton radiation therapy in the 1990s which renewed interest in the topic due to the potential benefits of imaging and treating patients with the same particle.
Wojciech (Wojtek) Zbijewski is an American biomedical engineering and medical physics working in the fields of Computed tomography (CT), Cone beam computed tomography (CBCT), image reconstruction in CT, and applications of CT and CBCT in orthopedics. He is faculty at the Department of Biomedical Engineering at Johns Hopkins School of Medicine.
Photon-counting computed tomography (PCCT) is a form of X-ray computed tomography (CT) in which X-rays are detected using a photon-counting detector (PCD) which registers the interactions of individual photons. By keeping track of the deposited energy in each interaction, the detector pixels of a PCD each record an approximate energy spectrum, making it a spectral or energy-resolved CT technique. In contrast, more conventional CT scanners use energy-integrating detectors (EIDs), where the total energy deposited in a pixel during a fixed period of time is registered. These EIDs thus register only photon intensity, comparable to black-and-white photography, whereas PCDs register also spectral information, similar to color photography.
Spectral imaging is an umbrella term for energy-resolved X-ray imaging in medicine. The technique makes use of the energy dependence of X-ray attenuation to either increase the contrast-to-noise ratio, or to provide quantitative image data and reduce image artefacts by so-called material decomposition. Dual-energy imaging, i.e. imaging at two energy levels, is a special case of spectral imaging and is still the most widely used terminology, but the terms "spectral imaging" and "spectral CT" have been coined to acknowledge the fact that photon-counting detectors have the potential for measurements at a larger number of energy levels.
Plesiotherapy is a radiation therapy modality in which a source of ionizing radiation is placed in contact with the exterior surface of the body.
X-ray diffraction computed tomography is an experimental technique that combines X-ray diffraction with the computed tomography data acquisition approach. X-ray diffraction (XRD) computed tomography (CT) was first introduced in 1987 by Harding et al. using a laboratory diffractometer and a monochromatic X-ray pencil beam. The first implementation of the technique at synchrotron facilities was performed in 1998 by Kleuker et al.