Intensity Modulated Radiation Therapy (IMRT) at Emory University

Intensity Modulated Radiation Therapy (IMRT) has been in research and clinical use at Emory Radiation Oncology since August 1998.  As of 2007, we have delivered more than 36,000 IMRT treatments to cancer patients.

Intensity Modulated Radiation Therapy (IMRT) uses computer-generated images to plan and then deliver even more tightly focused radiation beams to cancerous tumors than is possible with conventional therapy.  IMRT helps radiation oncologists achieve increased precision through a combination of computerized machines that produce and deliver the radiation (called medical linear accelerators), advanced planning and control software, and specialized mechanical devices used to shape the radiation beams.  This improved precision often allows the radiation oncologists to increase the radiation dose delivered to the tumor.  IMRT differs from conventional three-dimensional radiation therapy in two important respects:  inverse planning and intensity modulation.  "Inverse planning" refers to the practice of specifying intended radiation doses for the tumor and surrounding normal tissues; the treatment planning software then calculates the optimal radiation beam arrangement to satisfy these dose requirements.  In conventional treatment planning, the radiation beams are set manually, then dose distributions are calculated and reviewed to see if they are satisfactory.  "Intensity modulation" refers to the ability of IMRT to vary the strength of the radiation at different locations within the beam.  This is accomplished by dividing each beam into many small "beamlets" that essentially deliver radiation independently. 

IMRT's benefits to patients include reduced side effects and complications of radiation therapy, and in some cases greater probability of cure due to increased radiation dose to the tumor. IMRT may even permit radiation therapy to be given for some cancers that would not otherwise have been treated, giving those patients new hope of being cured.

IMRT represents one of the first uses of computer systems to optimize the radiation delivery technique. The IMRT planning system evaluates millions of possible beam arrangements and yields an optimized treatment plan. This plan maximizes the radiation dose delivered to the tumor while minimizing the radiation dose delivered to the surrounding normal tissues.  Emory's Department of Radiation Oncology has an industry partnership with Varian Medical Systems to help develop, test, and implement the latest technology solutions for IMRT. At Emory University we have recruited world-class faculty, developed collaborative research programs, and created partnerships with leading radiation therapy technology vendors to develop and implement IMRT at our institution. 

IMRT delivers less dose to normal tissue