Radiation Physics
Division Overview
Randy Ten Haken, PhD:
Director
of Radiation Physics
The Physics Division has continued its internationally recognized leadership in Radiation Oncology, with strong clinical and research programs which are tightly integrated with the clinical and research efforts of the other faculty in the department.
Some of the accomplishments of the division in Treatment Planning, Functional Imaging, Patient Modeling, Flat Panel Imager Development, NIH Projects, Clinical Operations and Teaching and Training Service are highlighted below (see Major Programs).
Faculty Members |
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Antonuk |
Balter |
Cao |
Fraass |
Hadley |
Kessler |
Lam |
Lee |
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Litzenberg |
Matuszak |
McShan |
Moran |
Narayana |
Prisciandaro |
Ritter |
Roberson |
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Physics Division Personnel(click to enlarge) |
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Roberts |
Ten Haken |
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Major Programs |
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Research Interests
Larry Antonuk, PhD: Professor and principle investigator of the Flat Panel Imager Group
James Balter, PhD: Professor and my research focuses on the interface of imaging sciences and advanced therapeutics.
Yue Cao, PhD: Professor and head of Functional Imaging Group.
Benedick Fraass, PhD: Director Emeritus.
Scott Hadley, PhD: Assistant Professor of Radiation Oncology
Marc Kessler, PhD: Allen S Lichter, MD Professor of Radiation Oncology
Kwok Lam, PhD: Clinical Associate Professor
Choonik Lee, PhD: Clinical Instructor and Associate Director of Medical Physics Residency Program
Dale Litzenberg, PhD: Clinical Assistant Professor
Martha Matuszak, PhD: Clinical Instructor
Daniel McShan, PhD: Professor and Associate Director of Division of Radiation Physics
Vrinda Narayana, PhD: Associate Professor and Chief Physicist, Providence and Assarian Cancer Centers
Joann Prisciandaro, PhD: Assistant Professor and Director of the Medical Physics Residency Program.
Timothy Ritter, PhD: Assistant Professor
Peter Roberson, PhD: Professor and Associate Director for Off Campus Program
Donald Roberts, PhD: Assistant Professor
Randall Ten Haken, PhD: Professor and Director of Physics Division
- Intensity modulated radiation therapy (IMRT) is now not only routinely performed, but, thanks to continuing developments within our in-house optimization system, also integrated into clinical research trials that seek to maximize the clinical gain in treatments of tumors located in the breast, prostate, head/neck, brain, liver, lung, pancreas, and other locations. Novel optimization techniques which make possible more intuitive plan optimization (lexicographic ordering) and smoother more robust IMRT plans (adaptive diffusion smoothing) have been developed and implemented for research and clinical use.
- New treatment planning techniques have been developed (through use of the new optimization tools) that systematically take advantage of heterogeneous target volume irradiation to improve the overall clinical effect (benefit/risk therapeutic ratio). Older, more standard techniques which sought to homogeneously treat target volumes were often limited in overall effective dose to the tumor by the maximum dose tolerated by nearby normal tissues
- We have also integrated the use of biological/mathematical models within the treatment planning optimization process, thus allowing full accounting of the anticipated effects of target and normal tissue irradiation throughout volumes of interest. Most standard optimization systems use single point dose constraints, which can mask the overall anticipated clinical impact of the dose distributions.
- We have begun to develop and build a fundamentally new bio-informatics approach to total patient treatment (including factors beyond the technical details of radiation delivery alone) within what we describe as a knowledge guided radiation therapy (KGRT) framework.
Multimodality and Functional Imaging
- We have developed magnetic resonance imaging (MRI) analysis tools to assess the responses of brain, head & neck, and liver tumors and surrounding normal tissues to radiation treatments. Examples include hepatic perfusion imaging as a potential early indicator of normal liver toxicity to treatment, and MRI studies of radiation damage to neuronal tissue and also the influence of radiation on chemotherapeutic access to intracranial targets.
- We have also developed image registration and analysis techniques to use Nuclear Imaging studies (positron emission tomography (PET) and single photon emission computed tomography (SPECT)) for the assessment of tumor and normal tissue responses to radiation treatments of the lung, breast, brain, and head & neck. Examples include better targeting through PET imaging of tumors and earlier indications of potential damage to normal lung and heart.
- The ability to coordinate the imaging studies (which can often demonstrate early signs of tissue response) with the dose distribution (which can be adjusted during the treatment process) will help enable truly individualized patient treatments. These projects exist through strong collaborations with colleagues in Radiology, Medical Oncology, and Surgery
Patient Setup and Organ Motion
- Research continues on minimizing effects of tumor and normal tissue motion due to patient breathing and setup uncertainty on single and multi-fraction radiation treatments. We use rapid anatomic imaging to improve our knowledge of breathing motion and other patient geometry changes over a course of treatment. We have on-going research evaluations of uses for “smart” electromagnetic localization and position monitoring systems, particularly for prostate treatments.
- We have demonstrated the relative importance of patient organ motion and shape changes due to breathing with respect to the delivered dose distribution. Traditional radiation plans based solely on a single (static) planning study do not take patient related changes in dose at the actual treatment into account. Integration of these effects, together with understanding of their relative importance, and advanced statistical analyses of anticipated improvements associated with image guided radiation therapy (IGRT) treatments allows the optimization of anticipated delivered dose
- Through collaborations with Electrical Engineering and Computer Science, we have developed an algorithm that uses prior patient models and sparse sampling to generate high temporal resolution models of patient breathing from relatively slow volumetric imaging systems such as cone beam computed tomography. Part of this has been the development of advanced signal analysis methods to facilitate tumor tracking studies. To assess the accuracy of this type of imaging, as well as to study deformable image registration in general, we have developed deformable phantoms capable of simulating breathing motion and presenting complex challenges to imaging and alignment techniques.
- A major milestone in the development of flat-panel imagers for monitoring radiotherapy was reported in the March 2007 issue of the journal Medical Physics. There, imaging performance approximately 20 times higher than that provided by current radiotherapy imagers was reported from an experimental prototype developed by our flat-panel imaging group in collaboration with industrial sponsors. This remarkable increase is expected to lead to improved image quality, at lower patient dose, thereby assisting the treatment verification process. It is also expected to eventually lead to the development of techniques to produce high contrast tomographic images using the treatment beam that could have a profoundly positive influence on the patient imaging process.
- We have completed an agreement to license application specific integrated circuits developed for flat-panel array research. Packaged versions of the circuits to be made available to our group will serve to significantly enhance our research capabilities.
- The on-going Program Project Grant led by Dr. Fraass has been refunded by the NIH for its third five year period of funding. This collaboration includes 39 faculty from our department as well as other departments in the Medical and Engineering Schools. This long-running grant is one of the largest physics-led Radiation Oncology grants in the country, and was refunded during a period of particularly difficult competition for limited NIH funding dollars.
- Following the receipt of an almost-perfect score from an NIH study section, a grant application for the renewal of the flat panel imaging group’s MASDA-R project was funded in July of 2006 (PI Larry Antonuk). This award marks the fourth round of NIH funding for this program of research and extends the research through years 11 to 14.
- We continue to collaborate with the Ultrafast Laser Optics Laboratory within the College of Engineering to investigate laser-acceleration of protons for therapy with a new NIH grant (PI: Dale Litzenberg). Laser acceleration of protons has the potential to provide a source of protons for therapy which is many times less expensive than current cyclotrons or synchrocyclotrons.
- Patient safety and effective treatment with the most modern technology remain as major priorities within the Physics Division, including the installation and quality assurance (QA) of treatment, imaging and dose computing equipment. We are now running five treatment machines, most with onboard imaging (OBI) equipment for patient setup verification. This important advancement allows the potential for Image Guided Radiation Therapy (IGRT) at each patient treatment.
- We have significantly streamlined our IMRT QA program through use of automated analysis software and associated process changes to enhance our ability to assure the safest possible patient treatments with this highly technical treatment delivery strategy in an efficient manner.
- We have installed a new multislice wide bore CT scanner for use in planning patient treatments. It will allow routine use of new imaging techniques including “4DCT” (which images volumetric (3D) position of tumors and organs throughout the breathing cycle (4D)). This also enables respiratory-gated and sorted images, multiple state studies, and fast patient acquisitions.
- We have implemented a massively parallel Linux computer cluster for sophisticated treatment planning research and clinical use, including treatment planning for IMRT and the use of Monte Carlo dose calculation algorithms for improved dose calculation accuracy.
New Clinical Programs
- A new High Dose Rate (HDR) brachytherapy program has been clinically commissioned, and is treating an increasing number of patients each week. The program will be able to treat even more patients once the dedicated HDR Suite is completed and put into clinical use.
- A stereotactic body radiotherapy (SBRT) program was initiated in late 2005. This program now routinely treats small targets in the lungs and liver, as well as paraspinal lesions presenting with too much risk to be treated conventionally. These treatments take advantage of modern technologies, including diagnostic radiography and cone beam computed tomography for localization, dynamic patient modeling at simulation, customized immobilization, and in-house researched breathing immobilization using active breathing control.
Teaching, Training and Service
- We expanded our Medical Physics Residency Training Program from 2 to 5 residents, including our first Israeli Medical Physics Resident.
- During 2006-7, we graduated 2 physics residents (UM Radiation Oncology) and 7 Ph.D. students (3 in Nuclear Engineering and Radiological Sciences, 2 in Electrical Engineering and Computer Sciences, and 1 each in BioEngineering and Industrial and Operations Engineering).
- Many of our physics division faculty participate as leaders and instructors at national and international meetings and workshops; four of us serve on the Board of Directors of national organizations (American Society for Therapeutic Radiology and Oncology (ASTRO), the American Association of Physicists in Medicine (AAPM) and the American College of Medical Physics (ACMP); five of us serve on national grant application peer review committees (“study sections”); and all of us routinely review papers for peer-reviewed scientific journals.
