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Mohan and Oelfke Receive SINF Awards

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The German Cancer Research Center (DKFZ) and MD Anderson’s Global Academic Programs’ Named Sister Institution Network Fund (SINF) Awardees

Radhe Mohan and Uwe Oelfke: Intensity Modulated Particle Therapy

The common DKFZ link for both MD Anderson and Radhe Mohan, Ph.D. is Wolfgang Schlegel, Ph.D., the head of The Department of Medical Physics in Radiation Oncology at DKFZ. In the early 90’s one of Schlegel’s students, Thomas Bortfeld, Ph.D., spent a year working with Arthur Boyer, Ph.D. at MD Anderson, followed by time at Memorial Sloan-Kettering Cancer Center in New York City, where he worked with Mohan. Bortfeld is now the Director of the Physics Division at Massachusetts General Hospital in Boston, MA. Mohan says the Intensity Modulated Radiation Therapy (IMRT) work in which he and Bortfeld engaged revolutionized the field of radiation therapy. IMRT provides high dose radiation conforming to the shape of the tumor target while protecting surrounding tissues.

The research laid the groundwork for Mohan’s continued work with Bortfeld as well as his current collaboration with DKFZ, a SINF awarded project with DKFZ collaborator Uwe Oelfke, Ph.D., focused on multiple aspects of Intensity Modulated Particle Therapy (IMPT).

IMPT, put simply, is the ability to adjust multiple beams of streaming particles and focus them on the location where the radiation is to be delivered. In the United States, however, we tend to think the P in IMPT is for proton. As research in places like Germany and Japan have demonstrated, however, carbon ions also show promise in treating cancer with focused particle beams.  While Mohan has been engaged in research using The MD Anderson Proton Therapy Center, and protons, Oelfke has similarly been investigating carbon ions for use in radiotherapy. Particle therapy has the potential to assist countless patients, and although the technology has been honed over the last 20 years for cancer treatment, many of the underlying complexities remain unresolved.

Energy absorbers are used reduce the spot size of the scanning beam of protons and carbon ions to improve the quality and conformality of IMPT.  These data (pictured above) illustrate the limitations of the current methods of computing radiation dose distributions in the presence of energy absorbers.  The proposed research will study the behavior of particles in the presence of energy absorbers and is expected to lead to methods that can accurately account for energy absorbers.

Whether proton or carbon, IMPT is planned based on the location to receive radiation. However, that location can change both during treatment, from breathing, for instance, and from day to day, such as through changes in stomach content. Known as intra- and inter-fraction changes, this means what was planned may change not only from one treatment to the next, but during a treatment session as well, thereby limiting the accuracy of the treatment plan. Mohan and Oelfke plan to work on how to minimize these inaccuracies by taking intra- and inter-fractional uncertainties into account during planning and gain a better understanding of how the particle beams interact with beam-line components and the patient’s anatomy. Both researchers believe bridging these gaps in understanding will lead to more widespread use of IMPT and ultimately provide improved outcomes for patients.

Although Mohan and Oelfke have known of each other for nearly a decade, and have bounced ideas off each other for close to five years, they had previously been unable to find a mechanism to foster their collaborative tendencies. When asked if the SINF enabled their collaboration, Mohan’s answer is unequivocal, “Absolutely. IMPT is a big area of study…the proposed research within the framework of SINF is just a small piece, but it is seed money,” explained Mohan. “We hope this will provide the foundation to apply for other grants through CPRIT and NCI and grow the research.”

© 2015 The University of Texas MD Anderson Cancer Center