News Release

SCIENCE HIGHLIGHTS of the 50th AAPM Meeting in Houston, July 27 to July 31

5. NEW RADIATION THERAPY METHOD OFFERS SHORTER TREATMENT TIME

Intensity modulated radiation therapy (IMRT) is a method of depositing radiation with varying intensities to different parts of cancerous tumors, while sparing the surrounding healthy tissue from excessive exposure. A new variant of IMRT, called volumetric modulated arc therapy (VMAT), promises further benefit to patients by offering the same treatment in half the time.

In the IMRT method, a computer-controlled linear accelerator sweeps a narrow (1-2 cm wide) slit of radiation across the tumor from five to nine angles around the patient, one angle at a time. The VMAT method, in contrast, delivers radiation in a 360-degree arc while the beam aperture shape continuously changes. A variant of the VMAT technique, proposed by Pengpeng Zhang (zhangp@mskcc.org), an assistant attending physicist at the Memorial Sloan-Kettering Cancer Center, and his colleagues Laura Happersett and Gig Mageras, breaks the arc into 360 evenly divided beams. A computer program developed by the researchers adjusts the aperture shape and radiation dose of each beam to maximize the radiation to the tumor while keeping healthy tissue exposure down at acceptable levels. Because the resulting beam apertures are much larger in VMAT than in IMRT, treatment time is substantially less and patient exposure to radiation leakage from the accelerator is reduced.

Zhang and his colleagues retrospectively evaluated the feasibility of this procedure in data from five patients treated for prostate cancer. The treatment times they calculated were reduced by up to 50 percent--from the 5 minutes typical for IMRT down to 2 ½ minutes-with a corresponding decrease in the amount of radiation leakage received by healthy tissues. Zhang hopes to extend the technique to the treatment of other cancers, including those of the head and neck, brain and pelvis.

Talk (TU-D-AUD B-2), "Volumetric Modulated Arc Therapy: Implementation and Evaluation for Prostate Cancer Cases" will be at 1:42 p.m. on Tuesday July 29, 2008 in Auditorium B. Abstract: http://www.aapm.org/meetings/amos2/pdf/35-8777-46582-702.pdf.

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HOW TO COVER THE MEETING

Reporters who would like to attend the meeting in person should fill out the press registration form on the AAPM Virtual Press Room. See: http://www.aapm.org/meetings/08AM/VirtualPressRoom/documents/pressregform.pdf.

Reporters who would like to cover the conference remotely will find releases and articles on the Virtual Press Room highlighting many of the interesting and important talks presented at the meeting. Even if you can't make it to Houston, the Virtual Press Room will make it possible to write stories about the meeting from your desk.

ABOUT AAPM

The American Association of Physicists in Medicine (AAPM) is a scientific, educational, and professional nonprofit organization whose mission is to advance the application of physics to the diagnosis and treatment of human disease. The association encourages innovative research and development, helps disseminate scientific and technical information, fosters the education and professional development of medical physicists, and promotes the highest quality medical services for patients. In 2008, AAPM will celebrate its 50th year of serving patients, physicians, and physicists. Please visit the association's Web site at http://www.aapm.org/.

ABOUT AIP

Headquartered in College Park, MD., the American Institute of Physics is a not-for-profit membership corporation chartered in New York State in 1931 for the purpose of promoting the advancement and diffusion of the knowledge of physics and its application to human welfare.

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Media contacts:

Jason Socrates Bardi, American Institute of Physics,
301-209-3091 (office) 858-775-4080 (cell)
jbardi@aip.org

Jeff Limmer, AAPM Media Relations Subcommittee Chair
jeffl@aspirus.org