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HOUSTON MEETING HIGHLIGHTS: Physics and the Future of Medicine
American Association of Physicists in Medicine Meeting, July 27 to July 31

6. PHYSICISTS PROVIDE "GUIDING HANDS" FOR PROTON THERAPY

Proton therapy offers great benefits as a treatment modality in radiation oncology for a variety of hard to treat tumors. While physicians manage the treatment of people, behind the scenes, proton physicists play a crucial role, providing support and guidelines for treatment planning for calculation of dose distributions, measurements of radiation delivery, measurements of proton beam data, quality assurance of all measuring equipment and of the proton accelerator, and calibration of proton beams, all essential to successful treatment outcomes.

Making the most of the characteristics of proton beams is the role of a team at M.D. Anderson Cancer Center using a proton machine for treatment of cancerous tumors. Proton therapy is a preferred method of treatment where limited radiation dose to critical organs is crucial, an option that may not be feasible to achieve in some instances when people are treated with high energy photon radiation. This is especially valuable in cases such as craniospinal irradiation for pediatric Central Nervous System tumors or in the treatment of people with lung cancer where dose can be restricted to the tumor without affecting nearby tissue and organs.

Currently two techniques are used for delivering proton beams. Passively scattered proton beams deliver uniform dose to the tumor and a small region of adjacent tissue and are shaped laterally by apertures and distally by compensators to reduce the dose to healthy tissue. M.D. Anderson Cancer Center has pioneered a second technique in North America that uses a pencil beam to focus the dose. The pencil beam delivers dose to the tumor at many different spots and multiple layers within the tumor, dramatically reducing the dose to healthy tissue as compared to passively scattered proton beams. The technique does not use apertures and compensators but instead restricts the dose by selecting the spots confined within the tumor. The dose calculation and the accuracy of delivery of these pencil beams is a complex process, but offers great advantages for sparing healthy tissue.

While proton therapy is improving both treatment and quality of life for people with tumors, there is still a great deal to be learned in order to maximize the benefits of this treatment modality. Dose delivery in an inhomogeneous media such as the human body needs to be further understood and investigated in order to assure more accurate dose calculation for optimal dose delivery to the tumor while sparing surrounding tissue, a major advantage offered by proton therapy. The M.D. Anderson team is hoping that their work will benefit others in the field. Dr. Bijan Arjomandy (barjomandy@mdanderson.org), a physicist at the M.D. Anderson Proton Therapy Center in Houston explains, "We hope that by sharing our experiences in developing such a QA program, we will provide an insight for new proton therapy facilities just establishing their programs," he says.

Talk (TH-D-352-6), "An Overview of Comprehensive Proton Machine Quality Assurance at the University of Texas M.D. Anderson Cancer Center" is at 1:30 p.m. on Thursday July 31, 2008 in Room 352. Abstract: http://www.aapm.org/meetings/amos2/pdf/35-8323-48323-548.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