Medical Physics Research Programs
Research Staff: Enrique Izaguirre
Brief Overview: microRT is defined as a system that is used to provide conformal irradiation for small animals for radiation effects experiments. The process includes the development of an irradiator, treatment planning system, process for the 3D imaging of the subject, and positioning verification system. more information
Research Staff: Dan Low, Wei Lu, Parag Parikh, James Hubenschmidt, Bob Drzymala
Brief Overview: The 4D CT group is actively engaged in developing 4D CT protocols that will be used to generate treatment plans for lung and upper abdominal cancers. The group studies the accuracy and precision of CT gating techniques to determine the ultimate uncertainty in the data generated for treatment planning. The information gathered studying 4DCT will be used to develop treatment plans that include ITV generation and linear accelerator gating. Investigations in 4D cone-beam CT are also underway.
Research Staff: Dan Low, Parag Parikh, and Kate Malinowski
Brief Overview: The 4D Phantom is a dynamic stage for radiological
phantoms capable of arbitrary motion and timing. It is capable of reproducing
complex translational tumor motion. The system can be used to test any part
of the radiation therapy process, from imaging to treatment. It is in the final
stages of development. more information
Modeling human breathing motion
Research Staff: Dan Low, Wei Lu, Parag Parikh
Brief Overview: Accurate 4DCT data can be used to describe internal organ motion due to breathing. A generalized mathematical description of human breathing motion has been generated that will greatly increase the utility of the 4DCT data. We are in the process of fine-tuning and validating the model. The model input parameters are obtained from high-quality 4DCT data and deformable image registration.
On-board imaging: Trilogy and Tomotherapy
Research Staff: Lakshmie Santanam, Eric Klein, Harold Li, James Hubenschmidt, James Grigsby
Brief Overview: While 3D conformal therapy and IMRT have provided unparalleled conformal therapy fields, they are typically defined using a single image dataset acquired prior to therapy. The radiation therapy treatment and ancillary therapies often change the physical shape and extent of the tumor and normal organs. The impact of this change on the conformation between the tumor, normal organs, and the dose distribution can have a profound impact on the quality of the delivered dose distribution. A new imaging capability, on-board imaging, provides computed tomography images that are obtained during the therapy session and coregistered with the delivery beam. The amount and quality of the image data, the process to make best use of the data, the sites that can best make use of this data, and methods for analyzing this data are still being developed.
Research Staff: Sasa Mutic,
Brief Overview: CT provides a highly spatially accurate image dataset of the patient’s anatomy by providing a map of the linear attenuation coefficients of the tissues within the body. The linear attenuation coefficients vary from tissue-to-tissue, including tumor tissues. However, the contrast is relatively low, especially for many tumors in the brain, abdomen and pelvis. This, along with the negligible change in linear attenuation coefficients from occult disease, means that CT has significant limitations in the determination of the extent of tumors. Tumors vary in their radiation response, and it is hypothesized that different regions of the same tumor vary in radiation response. Methods used to differentiate the tumor from normal tissues, categorize the tumor radiation sensitivity, or to categorize the tumor physiologic environment, are being developed in a wide variety of imaging modalities, including PET and MRI. We are involved in the development of these imaging modalities for radiation therapy applications, including fine-tuning of the image acquisition and analysis and use of the image information for treatment planning.
Research Staff: Murty Goddu, Sasa Mutic, James Grigsby
Brief Overview: A new technology for the optimal delivery of radiation has been developed by Tomotherapy, Inc. This technology includes radiation therapy treatment planning, 3D patient positioning verification, and radiation delivery using a technology that has the potential for providing the highest dose conformality of any commercial delivery system. Because the system is self-contained, the company has the potential for providing a closed-system process that maximizes on the use of on-board CT imaging and feeding that back to the dose distributions.
Automated IMRT QA
Research Staff: Harold Li, Dan Low
Brief Overview: One of the greatest concerns with the use of modern radiation therapy, IMRT, is the monitoring of the safe treatment. The character and delivery of dose distributions are more complex than ever before, so the need for QA has been increased, while the increased complexity has placed significant limitations on the quality of QA information. We envision a change in the way that IMRT QA is conducted, separating the QA of the linear accelerator, patient-specific treatment plan, and patient/tumor positioning on the day of treatment. This project concerns defining an automated QA process that can be conducted on a relatively frequent basis that quantitatively assesses the operation of the linear accelerator.
Advanced treatment planning applications
Research Staff: Sasa Mutic
Brief Overview: Radiation therapy treatment planning has evolved from the 2D era, through the 3D era, and is now entrenched in the IMRT era. The implementation of these eras has been preceded by a wave of research and development in process developent and QA. We are now in the era of developing 4D radiation therapy, adaptive radiation thearpy, and the implementation of biological imaging into the planning process. We have an active program to develop these areas with state-of-the art treatment planning systems.