The Status and Future of Medical and Industrial Accelerator Technologies

Medical and industrial accelerators have changed dramatically over the last decade in order to face the challenges of worldwide growth in cancer incidence and increased security risks. In the late 1990s, researchers working on medical accelerators for cancer care developed technology to "paint" dose in smaller and smaller beamlet sizes in order to spare normal tissues while placing higher doses into the tumor. In this decade, the addition of imaging equipment is allowing clinicians to better see what they are targeting just before they deliver a treatment. This same imaging technology-on-board radiographic, fluoroscopic and cone-beam CT imaging-is also being applied in industrial applications to better protect us from weapons of mass destruction by screening cargo and other materials moving across borders. Today, even newer tools are addressing the added challenge of tracking moving targets, whether they are tumors moving periodically as a result of respiration or cargo containers that must be scanned quickly and efficiently to avoid slowing the pace of commerce. New imaging and accelerator technologies are being developed in order to be able to act, in real time, on the basis of continually-changing information. There are many types of cancer that can now be successfully controlled with radiation therapy; however, there are others that continue to be challenging to treat. Lung cancer, for example, which kills more people worldwide than any other form of cancer, requires the delivery of high doses with great precision, in order to avoid acute and chronic side effects. Lung cancer treatment is complicated by the fact that these tumors often move during respiration, and they are surrounded by tissues that are extremely radiosensitive. Evidence is growing that lung cancer can be successfully treated with radiation; however, this will require further development of technologies that can adapt treatment to changes occurring within a physiological timeframe.