Introduction:

Intensity modulated radiation therapy (IMRT) is a dramatically improved method of planning and delivering therapeutic radiation treatments. It has allowed radiation oncologists to apply their treatments more effectively and safely. IMRT represents a significant leap in technology that can benefit cancer patients receiving radiation by reducing side effects and potentially improving cure rates.

What is IMRT?

With conventional radiation therapy (RT) both cancerous and normal tissues receive similar radiation exposure. With IMRT, the radiation is delivered so that selected cancerous tissues receive the desired full dose while adjacent normal tissue can be significantly spared.

Advanced software, dramatically more powerful computers and technological advances in the linear accelerators (treatment machines) were necessary in the development of IMRT. Multileaf collimators moving through the radiation beam during the actual treatment allow the radiation intensity to be altered in the treated field. Using multiple treatment fields delivered from different angles and computer-aided optimization, the necessary radiation is precisely delivered to often irregularly shaped tumor volumes.

Does it work?

The ability of radiation therapy to cure a cancer is often directly related to the amount of radiation that can safely be delivered. Some cancers require a higher dose than others. Until now, the more sensitive, surrounding normal tissues limited what could be given. The technique of IMRT, however, can sculpt the radiation distribution around the tumor and significantly spare adjacent normal tissue and keep them well within tolerable limits.

This ability has allowed the safe escalation of radiation dose to tumors. In several disease sites tumor control rates have improved. The dose used for prostate cancer is now over 20% higher, which has resulted in improved tumor control rates. The power of IMRT to confine the therapy to just the prostate and minimize rectal and bladder exposure has also reduced side effects.

Similar benefits are realized in head and neck, breast, rectal and gynecologic cancers making radiation therapy more effective and tolerable. Research continues in other disease sites to expand the use of this new technology.

In cases of recurrent cancer, IMRT can be used to successfully retreat patients. Again, the ability to spare nearby tissue from unnecessary exposure allows the potential for additional treatment.

Carolina Regional Cancer Center

Carolina Regional Cancer Center (CRCC) has been performing IMRT since mid-2002. Both of CRCC’s Varian linear accelerators are IMRT capable. Since the initiation of the program, over 1000 patients have been treated with this technique. CRCC will stay current as this field advances. Our goal, as always, is to provide the most modern and effective treatment for our patients.