Radiation is used as a treatment for many types of cancers and is delivered in various ways, depending upon the disease, its location, and its stage. Many specialists are involved in the delivery of radiation treatments: radiation oncologists, dosimetrists, medical physicists, and therapists. Below are some of the radiation therapies offered at UW Medical Center's Cancer Center and the Seattle Cancer Care Alliance.
Conformal Radiation Therapy is a high-precision method of delivering fractionated radiotherapy for tumors located in the sinuses, base of the skull, juxtaspinal cord region, and the prostate. It is a way of bringing in radiation beams from multiple directions to all parts of irregularly shaped tumors. Its utility requires a three-dimensional treatment planning computer, a variable multileaf collimator, and a means of obtaining accurate beam images. This technique increases tumor control and decreases complications. Treatment is given under the direction of board-certified radiation oncologists and medical physicists.
Coronary Arterty Brachytherapy - After coronary angioplasty procedures, stents (tiny hollow meshed or coiled pieces of metal) are implanted inside the lining of the vessel. The stent provides a mechanical scaffolding which maintains the opening created by the angioplasty. However, during the process of re-openeing, the section of the artery just treated becomes damaged. The vessel lining reacts to the trauma of the angioplasty procedure by forming scar-like lesions, which eventually can re-stenose (re-clog) the artery. In the past, a high percentage, approximately 20 percent, of patients given stents have re-stenosed.
The fact that cells are killed by exposure to radiation is how radiation therapy works in killing cancer. The same mechanism is responsible for stopping excess growth of vessel lining cells at the site of re-blockage. First, the vessel is re-opened, which is followed by irradiating the segment of the vessel just opened. A portable machine that contains small radioactive sources is used to deliver the radiation to the vessel lining. The machine inserts the sources into the vessel at the exact location of the blockage and a radiation dose prescribed by the Radiation Oncologist is delivered. The dose that is delivered is calculated based on the diameter of the artery and the strength of the radiation source. After being irradiated the cells lining the vessel can no longer proliferate and cause re-stenosis.
CT Simulation
Conventional simulation uses fluoroscopy and X-ray films to mark the patient for radiation treatment. CT scans (computerized tomography) provide a 3-D visualization of the patient's anatomy and target area, which used to occur in two separate patient appointments. At times, due to scheduling conflicts, these appointments were often on different days. CT Simulation combines two different procedures and technologies into a single procedure resulting in increased patient comfort and convenience.
Because these two procedures are now combined into one procedure, treatment start days have improved by more than seven days. CT Simulation is simple to use, yet complex in terms of producing precise data for accurate localization of a tumor. This new software enables the technologist to combine the information from other imaging studies, such as a magnetic imaging study (MRI, which shows soft tissue information). A CT study defines bony anatomy. The combination of these two studies provides a complete picture of the patient's normal anatomy and target area.
Fast Neutron Radiotherapy is a different type of radiation than conventional radiation, with different radiobiological properties. Compared to conventional radiation, neutrons deposit 20 to 100 times more energy, inflicting more damage to cancer cells, damage that is less readily repaired.
Intensity Modulated Radiotherapy (IMRT) is a new technique designed to deliver as much radiation as possible to the tumor volume while sparing nearby normal tissues as much as possible. The same type of radiation (high energy X-rays) is used as in traditional forms of radiation therapy, but the difference is in how the radiation beams are shaped and modulated in intensity.
This advance in radiation therapy has been made possible by advances in computer algorithms and computer speed and by new technology incorporated into the linear accelerators that produce the X-rays. The University of Washington has had an active research program for a number of years in developing and improving the algorithms, in testing the new technologies, and in verifying the safety and accuracy of the beam delivery.
There is no simple answer to the question, "Is IMRT the best treatment for my cancer?" The answer depends to some extent on simple geometry, such as the distance between the tumor and nearby sensitve organs and on the shape of the tumor. It also depends on the type and stage of the tumor. In many cases, 3-D conformal radiation therapy (3D CRT) can be used as effectively as IMRT. Basic physics research and clinical trials are on-going at UWMC and at many other centers throughout the world in an effort to determine the most appropriate uses for IMRT.
What is clear is that the capability to plan and deliver IMRT gives your physician one more means by which to provide the best treatment possible for your particular cancer.
Interoperative Radiotherapy is a method of delivering radiation during surgery by directly exposing cancers to electron beam radiation with normal structures being removed from the treatment field. It is used to treat gynecologic cancers, colorectal tumors, biliary tract tumors, retroperitoneal tumors, and certain recurrent head and neck tumors. This treatment is coordinated by board-certified radiation oncologists and surgeons, with consultation from other medical specialties as needed.
Interstitial Brachytherapy refers to surgically implanting radioactive seeds or isotopes into the tumor. The isotopes may be placed permanently for low-activity sources, or for a specified period of time for high-activity sources permitting a higher dose of radiation to the tumor relative to the dose received by normal tissue. This is used to treat cancers of the brain, head and neck, breasts, uterus, cervix, prostate, and certain soft tissue sarcomas
Interstitial Breast Brachytherapy is a new treatment option for early-stage breast cancer given after breast-conserving surgery now offered at the UW Medical Center Cancer Center.
Current standard treatment for early-stage breast cancer includes adjuvant external-beam radiotherapy to the whole breast, delivered five days a week over a period of approximately six weeks. The goal is to decrease local tumor recurrence after lumpectomy.
Interstitial brachytherapy involves the temporary placement of plastic catheters directly into the tumor bed following lumpectomy. These catheters are “afterloaded” with a radioactive source to deliver a highly localized dose of radiation to the tumor bed twice a day for four or five days. The dose of radiation is biologically equivalent to the dose delivered by conventional external beam treatment.
Interstitial brachytherapy has a long history of use in many cancer sites and has been used for several years as a “boost” treatment in conjunction with external beam adjuvant breast radiotherapy. Several studies using interstitial brachytherapy for partial breast irradiation as sole radiation treatment, have been completed. Data from a total of several hundred women demonstrate local recurrence rates at three to four years ranging from two to four percent, very comparable to what is seen with external beam therapy.
The primary advantages of brachytherapy treatment over external beam treatment include very localized treatment volume with maximal sparing of surrounding normal tissues (lung, heart) from unnecessary radiation exposure, as well as a shorter treatment course (one week vs. six-plus weeks). These characteristics make this treatment especially ideal for breast cancer patients who might have prior exposure to radiation treatment (e.g. for Hodgkins lymphoma), for working women, or for women who live at some distance from a radiotherapy center.
Not all patients are good candidates for this therapy. Our radiation oncologist will make that determination.
Breast Brachytherapy Patient Information
Organ Preservation Therapy refers to the use of radiation with or without chemotherapy to treat tumors and avoid radical surgery. It preserves organ appearance and function and is used to treat breast cancer, laryngeal cancer, rectal cancer, anal cancer, esophageal cancer, and certain other malignancies. It is delivered under the care of board-certified radiation oncologists, oncologic surgeons, and medical oncologists.
Pediatric Radiation Oncology is provided at UWMC in collaboration with Children's Hospital & Regional Medical Center. Ionizing radiation for pediatric malignancies involves board-certified radiation oncologists with special training in the treatment of pediatric malignancies. Appropriate use of anesthesia to immobilize very young children is used following consultation with anesthesiology service. Approximately 95 percent of all children with cancer in Washington, Wyoming, Alaska, Montana, and Idaho are treated here.
Prostate Cancer Radiation is a preferred method of treatment, and a number of radiation options are available. Treatment may involve the implantation of radioactive pellets into the prostate, a procedure referred to as "prostate brachytherapy." Or, treatment may be delivered using a series of outpatient X-ray treatments. This latter approach focuses multiple radiation beams on the prostate, contouring the dose to the tumor and avoiding adjacent normal tissues and organs. This type of treatment is also referred to as "conformal radiation therapy" or "IMRT." There are clinical situations when it may be desirable to use a combination of external beam radiation as well as a prostate seed implant for specific patients. Additionally, there are times when it is advantageous to combine hormonal treatment with radiation.
Stereotactic Radiosurgery is a high precision method of delivering focused beams of radiation using a modified linear accelerator. The precision of treatment delivery is approximately 0.2 mm. A team of board-certified neurosurgeons, radiation oncologists, and medical physicists, with consultation from specialists in head and neck surgery, medical oncology, diagnostic radiology, and pathology work together to provide this treatment. This is used for cancer in the brain when surgery is inappropriate. This technique is useful for tumors adjacent to the spinal cord and other critical areas and complements the stereotactic radiosurgery for brain tumors provided with Harborview's Gamma Knife.