New Advances in Radiation Therapy
At the University of Chicago Hospitals, radiation oncologists apply state-of-the-art techniques to treat cancer with radiation therapy. Using the most advanced equipment available, these physicians are able to deliver radiation treatments accurately, effectively, and with the least amount of unwanted side effects. Our department has pioneered the use of these innovative treatments. We are also part of the cancer program ranked best in the state and among the nation's top 10, according to U.S. News & World Report. This rare combination of expertise and technology does make a difference in treating cancer.
Cancer patients usually need more than one form of cancer therapy to best treat the disease. For this reason, our radiation oncologists work closely with medical and surgical oncologists to create the most effective treatment plan to suit each patient's needs. In addition to advanced radiation therapy, the University of Chicago Hospitals offers trials of new cancer medications and the latest surgical techniques to fight cancer.
Radiation therapy is an effective treatment for many types of cancers. The most common form of radiation therapy uses multiple beams of high energy X-rays focused on the tumor from several directions. A medical linear accelerator, shown here, is used to generate the X-ray beams.
The effectiveness of radiation therapy usually can be improved by raising the amount of radiation delivered to the tumor. However, the radiation dose that can be delivered often is limited by the radiation tolerance of nearby healthy tissues.
3D Conformal Radiation Therapy: A Tailor-Made Cancer Treatment
3D conformal radiation therapy is a relatively new treatment technique developed to improve the precision with which radiation is delivered to tumors, thus minimizing radiation dose to healthy tissues. Conformal treatments are designed so that the region of high-dose irradiation conforms, as closely as possible, to the three-dimensional shape of the tumor. This conformation is achieved by applying multiple conformal-shaped beams, focused on the tumor from several different directions.
To minimize damage to healthy tissues, a high level of geometrical accuracy must be achieved throughout the treatment planning and delivery process. At the University of Chicago, medical physicists create a sophisticated three-dimensional model of the patient's internal anatomy, and use it to design a patient-specific conformal beam arrangement. During treatment, the geometric accuracy is verified using X-ray images of the patient, actually made with the conformal therapy beams. The result is high-precision radiotherapy.
A detailed model of each patient's anatomy is constructed from a CT scan. This example shows a tumor in red along with normal anatomy, such as the brain, spinal cord, and eyes, to be avoided during treatment.
Intensity-Modulated Radiation Therapy: A Stronger, More Effective Treatment With Fewer Side Effects
Intensity-modulated radiation therapy (IMRT) is the newest form of 3D conformal radiation therapy. Already, it is being hailed as the most important technical advance in radiation oncology in the past 40 years. The University of Chicago Hospitals is one of a select group of centers nationwide to offer this remarkable technology. IMRT's unique approach is to use real-time computer control of the linear accelerator, not only to shape beams, but also to vary the intensity of radiation within each beam. Nationwide clinical trials indicate that the IMRT approach allows more precise and effective radiation doses to be delivered to tumors with no increase in the dose to normal organs and tissues. In addition to these benefits, IMRT sessions often can be performed in less time than standard radiation treatments.
The new technology that makes IMRT possible is the dynamic multi-leaf collimator. A multi-leaf collimator consists of narrow metal leaves that are under computer control. In dynamic mode, the leaves move while the radiation beam is on and are used to three-dimensionally sculpt the treated region to the shape of a tumor.
Schematically drawn on these CT slices are the contours of a patient's prostate, bladder and rectum. Using standard radiation therapy techniques (left), the full tumor dose extends well beyond the target, irradiating significant portions of bladder and rectum. Using IMRT (right), the high dose region can conform more closely the target, avoiding the bladder and rectum.
Standard technique. The blue outline represents the treated region. Note that the dose far extends the target, outlined in red.
New IMRT technique. The treated region, shown in blue, is sculpted to the shape of the target, thus sparing healthy tissue from damage.
Our deparment is exploring the use of IMRT for all types of cancers, including those of the head and neck, pancreas, prostate, female pelvis, breast and lung. We also have developed new patient positioning technologies for ensuring that the patient and the radiation beams are aligned with the required precision so that the daily treatments that comprise a typical course of radiation therapy can be repeated with the utmost accuracy.