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Medical & Health Physics Research - Areas of Research Concentration
Medical Physics Research
Intensity-modulated Radiotherapy: 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). This
research is being done by Dr. Hogstrom as part of a research agreement
with TomoTherapy, Inc. 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. This research is
being done by Dr. Hogstrom as part of a research agreement with Varian
Medical Systems, Inc.
Image-guided Radiotherapy: Drs.
Hogstrom, Gibbons, and Parker 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 megavoltge 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, Sajo, and Varnes, 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. (www.mxisystems.com).
Prostate Brachytherapy
Dosimetry: Faculty members have recently received
a US Patent on a proposed new method for the direct dosimetry of permanent
interstitial prostate implants (seeds). Traditional prostate dosimetry
entails the tedious and error-prone task of identifying and locating
the implanted radioactive seeds on anatomical images following treatment.
The new method allows direct determination of the dose distribution
without the intermediate step of explicitly finding the seeds. Thus,
both the accuracy and required time in mapping the dose should be improved.
Dr. Sajo and Dr. Matthews are presently researching this proposed method.
Radioisotope Imaging Systems: Dr.
Matthews is pursuing research in radioisotope imaging. Radioisotope imaging
uses radioactive materials injected into a patient or subject to evaluate
physiological function. Positron emission tomography (PET) and single-photon
imaging are common methods for radioisotope imaging. Current projects include:
- development of hand-held CZT detector systems for intraoperative imaging;
- development and performance characterization of a compact CZT-based
gamma camera;
- development of a modified gamma camera design to facilitate coincidence
imaging of PET radiotracers;
- observer performance study to evaluate acquisition protocols for commercial
clinical PET/CT systems;
- methods for performance assessment and quality assurance of PET/CT
imaging systems.
Intravascular Radioisotope Imaging: Drs.
Shikhaliev and Matthews are developing methods for intravascular imaging
of radiopharmaceuticals (e.g., 18F-fluorodeoxyglucose). This approach
utilizes storage phosphor detectors mounted on the end of a catheter
to detect radiotracer uptake in vulnerable plaques in coronary arteries.
[Phys. Med. Biol. 51: 963-979 (2006)].
X-ray Imaging Detectors: A
current project is the development of photon counting detectors for x-ray
imaging and computed tomography (CT). The use of CZT detectors, tilted
relative to the x-ray beam, facilitates both photon counting and energy
weighting. Energy weighting allows a reduction of scattered radiation
and good dose efficiency for imaging. [Phys. Med. Biol. 51:
4267-4287 (2006)].
Health Physics Research
Radiation Damage in DNA: Dr.
Sajo conducts fundamental research in radiation biology in cooperation
with faculty members in the Department of Physics and Astronomy and the
Department of Biological Sciences to quantify genetic effects of high versus
low linear energy transfer (LET) radiation by examining interaction physics
at the DNA molecular level. This work may help researchers to understand
more clearly the damage mechanism of radiative energy deposition in human
tissue, and thus the relationship between radiation exposure and disease
formation. A major grant proposal has been submitted to NASA to investigate
the mutation spectrum caused by galactic radiation of extremely high energy
and high mass particles. This research will facilitate the assessment of
the risks of prolonged manned missions in outer space.
Aerosol Transport: The
US Department of Energy (DOE) is funding an experimental and numerical
modeling study aimed at understanding how aerosolized particles disperse
in enclosed environments. This work, directed by Dr. Sajo, may be used
to predict the behavior of radioactive or other hazardous materials in
indoor environments following accidental releases, and can also be applied
to analyzing terrorism threats from bacterial and germ warfare agents.
In addition, the work provides a better understanding of how aerosols travel
in human airways. A major application of this research would be improving
ways to deliver aerosol medications.
Radiation Detectors for Medical
Physics, Health Physics and Security Applications: Faculty
and graduate students are developing novel instruments and methods
for radiation detection applications in radiation protection, dosimetry,
and nuclear security.
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