Areas of Research Concentration
Medical Physics Research
Medical physicists at Mary Bird Perkins Cancer Center are studying the fundamentals and clinical potential of using intensity modulated x-ray therapy (IMXT) in lieu of or in conjunction with modulated electron therapy (MET). Parallel to this work, applications of an electron multi-leaf collimator (eMLC) to MET are being studied and compared to utilization of compensating wax bolus to achieve energy modulation.
Electron Beam Radiotherapy
Improved treatment planning and delivery of electron beam radiotherapy is a major focus of research by Dr. Hogstrom and his research team. Electron beam dose distributions used to treat cancer-bearing treatment volumes within 6 cm of the skin surface can be made more conformal by modulating dose penetration across the electron beam, and one method of achieving this utilizes wax bolus, which is referred to as bolus electron conformal therapy (ECT). A research agreement with .decimal, Inc., funds research to improve bolus ECT, e.g. mixing it with a small fraction of IMXT to produce mixed-beam distributions superior to either modality alone. For alternative delivery methods, which utilize energy-segmented fields, the challenges of treatment planning, abutment dosimetry, and MLC delivery have been investigated. Analytical calculations using radiation transport calculations and EGSNRC Monte Carlo calculations have been used to study these problems, as well as to design dual scattering foils and collimating systems, the latter funded by a research agreement with Elekta, Inc. Such research requires accurate dose measurement methods, a specialty of the research group.
Proton radiotherapy is an emerging technology that utilizes the finite range and sharp characteristic Bragg peak of proton beams to treat tumors to high doses while minimizing dose to surrounding normal tissue. Dr. Newhauser's research group investigates the efficacy of proton therapy compared to other methods, including risk prediction of secondary effects. Dr. Newhauser's group is also investigating microdosimeters for measuring radiation dose at cellular scales. In another effort, led by Drs. Fontenot and Hogstrom, members of the medical physics team at Mary Bird Perkins Cancer Center are developing dose calculation algorithms for the dielectric wall proton radiotherapy accelerator that model the transport of protons through the treatment head and patient. Potential applications of dose calculation algorithms include clinical treatment planning and real-time quality assurance. Funding and collaboration to support this research is expected soon from the Department of Defense and TomoTherapy, Inc., respectively.
Drs. Fontenot and Hogstrom at Mary Bird Perkins Cancer Center are conducting research in image-guided radiation therapy physics, gated radiotherapy, and adaptive radiotherapy. One research program concentrates on usage of orthogonal x-ray imaging using the BrainLab Novalis for radiosurgery and radiotherapy of brain and extra-cranial cancers, e.g. spine, liver, and prostate. Another program focuses on usage of megavoltage CT scanning using the TomoTherapy HiART for radiotherapy of prostate, head and neck, and many other anatomical sites. These programs are currently supported by research agreements with BrainLAB, Inc. and TomoTherapy, Inc., respectively.
X-ray Capture Therapy
X-ray capture therapy is a potentially new radiotherapy paradigm (chemo-irradiation) that uses monochromatic x-rays to deliver targeted radiation dose to high-Z labeled (e.g. iodine) pharmaceuticals that are preferentially taken up by cancer cells, e.g. IUdR taken up by DNA. Our research program, led by Drs. Hogstrom, Varnes and Matthews, uses the CAMD synchrotron’s monochromatic x-ray beam line to study dosimetry techniques, treatment planning dose algorithms, microdosimetry, cell biology, and small animal irradiations. Our long term goal is to conduct clinical trials using a prototype laser-particle accelerator to produce monochromatic x-rays such as one developed by MXI Systems, Inc.
Faculty and students are developing a new x-ray imaging technique, endorectal digital prostate tomosynthesis (endoDPT). endoDPT is expected to improve resolution in prostate cancer imaging for certain clinical applications. Current efforts include quantitative testing of image quality and patient dose on their prototype imaging system, development of tomosynthesis image reconstruction algorithms, and development of seed localization algorithms for low dose rate brachytherapy post-implant evaluations.
Nuclear Medicine Imaging
Drs. Dey and Matthews are pursuing research in medical nuclear imaging. Current detector development projects include high-sensitivity cardiac SPECT imaging as well as hand-held and compact CZT imaging systems for intraoperative imaging. Graduate students with Dr. Matthews have also worked on topics such as observer performance studies for PET/CT, quality assurance methods for PET/CT, performance characterization of megavoltage CT imaging for radiotherapy applications, and dose reduction for CT lung screening. A second research area for Dr. Dey is tumor modeling based on oncology imaging data.
Research in Health Physics and Nuclear Science
Radiation Detection, Dosimetry and Environmental Impacts
Health physics research includes radiation detector development with safety/security applications and intercomparisons of dosimetric methods by Drs. Wang and Matthews. Dr. Wang and students also work on environmental impacts of radiation use, currently including an environmental assessment of a hypothetical low-level radioactive waste repository located in Louisiana.
Space Radiation and Applied Nuclear Physics
Dr. Chancellor and the Space Radiation Transport and Applied Nuclear Physics group (SpaRTAN Physics) are focused on ascertaining the impact space radiation has on both the health of human spaceflight crews and the resilience of space vehicle hardware systems. Both of these efforts require a multidisciplinary approach; and the group partners closely with radiobiologists, aerospace physicians, engineers, and applied scientist to develop novel methods for studying the interaction of the heavy-charged nuclei found in the cosmic ray spectrum with both soft and condensed matters. The SpaRTAN Physics group utilizes high-performance, multi-core computers and sophisticated numerical techniques in order to study these complex interaction dynamics that are otherwise difficult to mimic in a laboratory setting. An example would be the utilization of Monte Carlo techniques to model spallation reactions of heavy charged nuclei interacting with hydrogen-rich materials and the angular discrepancy in off-axis fragments produced by inelastic nuclear interactions in particle transport code. Our computational outcomes are experimentally validated with measurements at beam line accelerators or by applying our models to results previously published in peer-reviewed literature. These efforts have led to novel approaches to simulating the complex space radiation environment and the development of more realistic ground-based space radiation analogs.