Fermilab operates the most powerful particle accelerator in the world. It was built for high-energy physics research. The cancer treatment at Fermilab is possible because Fermilab's Linear Accelerator (Linac), provides beam for both high energy physics research and neutron radiation therapy. Under computer control the Linac beam is automatically switched to the treatment room as needed for patient treatment.
Under computer control the Linac beam is automatically switched to the treatment room as needed for patient treatment.
To create the neutron beam, the space between two of the radiofrequency accelerating tanks in the linear accelerator was increased to allow room for a bending magnet. This magnet deflects protons from the Linac into the clinical beam line where they strike a beryllium target. Interactions between protons and beryllium atoms produce neutrons. An absorbing wall with an
appropriately tapered hole is located between the neutron source and the patient. The opening size is adjustable, and beam-shaping devices are used to assure that radiation is delivered only to the part of the body that the physician wants to treat. NIUINT at Fermilab has the highest-energy clinical fast neutron beam in the United States. This beam has the best tissue-penetrating ability and, therefore, the best capability for treating deep-seated, large tumors.
The treatment room is an elevator having two levels. The upper level contains x-ray equipment and low-power lasers used to position the patient for treatment. The neutron beam is located at the lower level, where the actual treatment occurs. After treatment the patient is raised to the upper level where he or she is accompanied to the waiting room.
An isocentric system is used to adjust the patient position between exposures. Each exposure to the beam lasts from one to three minutes. Treatment times are shorter than at any other fast neutron treatment center because the Fermilab beam has higher intensity, and therefore, a higher dose rate than any other facility in the world. Total treatment time, including set-up and irradiation, is 20-30 minutes depending on the complexity of the setup. There is no pain involved in the treatment process. During treatment the patient is observed by a closed circuit television, and communication is maintained by an intercom system. Generally, treatment is given three times a week for four weeks.