Radiation therapy is the use of high-energy x-rays to destroy cancer cells and shrink tumors. Cancer cells reproduce faster than normal cells in the body. Radiation therapy targets these rapidly dividing cells. The radiation reacts with water in the cells, and this reaction damages the DNA or genetic material in the cell that controls cell growth. Most normal cells can recover from the effects of radiation and function properly. Cancer cells can’t repair themselves easily and they are destroyed. The goal of radiation therapy is to damage as many cancer cells as possible, while limiting harm to nearby healthy tissue.
There are different types of radiation and different ways to deliver the radiation. For example, certain types of radiation can penetrate more deeply into the body than can others. IN addition, some types of radiation can be very finely controlled to treat only a small area (an inch of tissue, for example) without damaging nearby tissues and organs. Other types of radiation are better for treating larger areas.
In some cases, the goal of radiation treatment is the complete destruction of an entire tumor. In other cases, the aim is to shrink a tumor and relieve symptoms. In either case, doctors plan treatment to spare as much healthy tissue as possible.
About half of all cancer patients receive some type of radiation therapy. Radiation therapy may be used along or in combination with other cancer treatments, such as chemotherapy or surgery. In some cases, a patient may receive more than one type of radiation therapy.
Radiation therapy may be used to treat almost every type of solid tumor, including cancers of the brain, breast, cervix, larynx, lung, pancreas, prostate, skin, spine, stomach, uterus, or soft tissue sarcomas. Radiation can also be used to treat leukemia and lymphoma (cancers of the blood-forming cells and lymphatic system, respectively). The radiation dose to each site depends on a number of factors, including the type of cancer and whether there are tissues and organs nearby that may be damaged by radiation.
For some types of cancer, radiation may be given to areas that do not have evidence of cancer. This is done to prevent cancer cells from growing in the area and receiving the radiation. This technique is called prophylactic radiation therapy.
Radiation therapy also can be given to help reduce symptoms such as pain from cancer that has spread to the bones or other parts of the body. This is called palliative radiation therapy.
There are two main types of radiation therapy. Patients may receive one or the other, or a combination of the two. The Radiation Oncologist will discuss the options beforehand and make recommendations based on each individual’s specific condition.
The most common is external beam radiation, which is when a machine outside your body aims radiation at cancer cells. For patients, the treatment process is as painless as having an X-ray taken.
Internal radiation therapy, on the other hand, is when radiation is put inside your body, in or near the cancer cells. It may be left in place for a few hours, many hours, or even days. In some cases you may swallow the radioactive material, or it may be injected into your body. As time goes by, almost all the radiation will go away, even though the implant stays in your body.
The type of radiation to be given depends on the type of cancer, its location, how far into the body the radiation will need to go, the patient’s general health and medical history, whether the patient will have other types of cancer treatment, and other factors.
Most people who receive radiation therapy for cancer have external radiation, but some patients will receive both external and internal radiation therapy. External radiation therapy usually is given on an outpatient basis and is used to treat most types of cancer, including cancer of the bladder, brain, breast, cervix, larynx, lung, prostate, and vagina. IN addition, external radiation may be used to relieve pain or ease other problems when cancer spreads to other parts of the body from the primary site.
The energy (source of radiation) used in external radiation therapy is generated by a machine called a linear accelerator. Depending on the amount of energy the x-rays have, they can be used to destroy cancer cells on the surface of the body (lower energy) or deeper into tissues and organs (higher energy). The machine is normally the size of a small room measuring 10 feet high and 15 feet long. Treatment begins by having the patient lie down on a movable treatment table while the linear accelerator delivers beams of radiation to the tumor from multiple directions or angles. Lasers are used to make sure the patient is in the proper position. The intensity of each beam’s radiation dose can be varied according to the patient’s treatment plan.
To ensure patient safety at the June E. Nylen Cancer Center, several safety systems are built into the linear accelerator so that it will deliver the prescribed dose intended by the Radiation Oncologist. During treatment, the radiation therapist continuously monitors the patient both visually and audibly.
The amount of radiation absorbed by the tissues is called the radiation dose. Difference tissues can tolerate various amounts of radiation. For example, the liver can receive a much higher dose than the kidneys. The total dose of radiation is usually divided into smaller doses that are given daily over a specific time period. This maximizes the destruction of cancer cells while minimizing the damage to healthy tissue.
Cancer patients receiving radiation therapy are often concerned that the treatment will make them radioactive. The answer to this question depends on the type of radiation therapy being given.
External radiation therapy will not make the patient radioactive. Patients do not need to avoid being around other people because of the treatment.
Internal radiation therapy that involves sealed implants emits radioactivity, so a stay in the hospital may be needed. Certain precautions are taken to protect hospital staff and visitors. The sealed sources deliver most of their radiation mainly around the area of the implant, so while the area around the implant is radioactive, the patient’s whole body is not radioactive.
Many health care providers help to plan and deliver radiation treatment to the patient. The radiation therapy team includes the radiation oncologist, a doctor who specializes in using radiation to treat cancer; the dosimetrist, who determines the proper radiation dose; the radiation physicist, who makes sure that the machine delivers the right amount of radiation to the correct site in the body; and the radiation therapist, who gives the radiation treatment.
The radiation oncologist also works with the medical or pediatric oncologist, surgeon, radiologist (a doctor who specializes in creating and interpreting pictures of areas inside the body), pathologist (a doctor who identifies diseases by studying cells and tissues under a microscope), and others to plan the patient’s total course of therapy. A close working relationship between the radiation oncologist, medical or pediatric oncologist, surgeon, radiologist, and pathologist is important to planning total therapy.
Because there are so many types of radiation and many ways to deliver it, treatment planning is a very important first step for every patient who will have radiation therapy. Before radiation therapy is given, the patient’s radiation therapy team determines the amount and type of radiation the patient will receive.
If the patient will have external radiation, the radiation oncologist uses a process called simulation to define where to aim the radiation. During simulation, the patient lies very still on an examining table while the radiation therapist uses a special X-ray machine to define the treatment port or field — the exact place on the body where the radiation will be aimed. Most patients have more than one treatment port. Simulation may also involve CT scans or other imaging studies to help the radiation therapist plan how to direct the radiation. The simulation may result in some changes to the treatment plan so that the greatest possible amount of healthy tissue can be spared from receiving radiation. The simulation visit is a key part of treatment; the visit may take several hours, but treatment is not given that day.
The areas to receive radiation are marked with either a temporary or permanent marker, tiny dots or a “tattoo” showing where the radiation should be aimed. These marks are also used to determine the exact site of the initial treatments if the patient should need radiation treatment later.
Depending on the type of radiation treatment, the radiation therapist may make body molds or other devices that keep the patient from moving during treatment. These are usually made from foam, plastic, or plaster. IN some cases, the therapist will also make shields that cannot be penetrated by radiation to protect organs and tissues near the treatment field.
When the simulation is complete, the radiation therapy team meets to decide how much radiation is needed (the dose of radiation), how it should be delivered and how many treatments the patient should have.
Trilogy is a state-of-the-art machine that has the ability to perform highly complex Intensity Modulated Radiation Therapy and Image Guided Radiation Therapy treatments. The machine works with computer technology to assist in targeted and advanced forms of radiation therapy.
Image Guided Radiation Therapy (IGRT)
IGRT is the use of treatment room imaging modalities (i.e. X-ray, ultrasound, and CT scans) to precisely target a tumor for daily radiation treatment. Using image guidance for tumors affected by organ motion and day-to-day set up changes can lead to increased tumor response and/or decreased side effects from treatment. Utilizing the new CT on rails system, physicians are able to accurately target the treatment area by combining radiation machine and images of the patient anatomy taken by a CT scanner.
Intensity Modulated Radiation Therapy (IMRT)
IMRT is another treatment technique used to deliver highly accurate doses of radiation to irregularly shaped tumors with fewer adverse side effects. Pencil-thin beams of varied intensity conforms the radiation to the share of the tumor, allowing physicians to attach the cancer with the higher doses of radiation while minimizing damage to nearby healthy tissue and organs. Because IMRT equipment is highly specialized, not every cancer treatment center offers IMRT. June C. Nylen Cancer Center has a strong and ongoing commitment to bringing our patients the best and most current therapies.
Stereotactic Radiosurgery (SRS)
Stereotactic Radiosurgery (SRS) allows tumors to be destroyed with surgery — “Surgery without a Scalpel.”
Radio surgery is a radiation delivery procedure that precisely delivers large radiation doses to tumors and other relevant anatomical targets in a single session or in a series of sessions (typically up to five). The goal of this non-invasive procedure is to destroy, or render inactive, the target anatomy without harming healthy tissue and without involving traditional surgery, and avoiding anesthesia.
Stereotactic Body RadioSurgery (SBRT)
Stereotactic Body Radiotherapy, or SBRT, a type of external radiation therapy, is available at the Nylen Cancer Center. Ive the past, the fear of exposure to radiation and the high cost of a CT scan meant many patients went unscreened until the disease was advanced and had caused other illness, such as pneumonia.
With the SBRT capabilities, the low dosage of radiation given off during a CT is similar to the dose received during a mammogram.
Internal Radiation Therapy – Brachytherapy
Brachytherapy is a form of radiation that involved the placement of radioactive sources into a tumor or in an area where a tumor was removed. This technique allows for the delivery of high doses of radiation therapy while simultaneously sparing normal tissue.
The word “brachytherapy” means “short therapy,” appropriately implying that the radiation is limited to short distances. This results in decreased toxicity to normal tissues and also allows a higher radiation dose to the tumor.
Internal radiation therapy (or brachytherapy) uses radiation that is placed very close to or inside the tumor.
The radiation source is usually sealed in a small holder called an implant. Implants may be in the form of thin wires, plastic tubes called catheters, ribbons, capsules, or seeds.
The implant is put directly into the body. Internal radiation therapy may require a brief hospital stay. The radiation is emitted outward, unlike external beam radiotherapy, where radiation travels through normal tissue in order to reach the tumor.
Brachytherapy is often used to treat prostate, gynecologic, and breast malignancies. The radiation oncologist travels to the Siouxland Urology office to perform this procedure for prostate cancer patients, increasing patient convenience.
3-D Radiation Therapy
June E. Nylen Cancer Center offers the innovation of 3-Dimensional Conformal Radiation Therapy. Traditionally, the planning of radiation treatments has been done in two dimensions (width and height). Three-dimensional conformal radiation therapy (3-D Therapy) uses computer technology to allow doctors to more precisely target a tumor with radiation beams by using width, height, and depth.
A 3-D image of a tumor is obtained using a CT scan, MRI, or PET scan. Using information from the image, special computer programs design radiation beams that “conform” to the shape of the tumor.
Because the healthy tissue surrounding the tumor is largely spared by this technique, higher doses of radiation can be used to treat the cancer without increased side effects. Improved outcomes with 3-D therapy have been reported for nasopharyngeal, prostate, lung, liver, and brain cancers.