What is radiation therapy?
Radiation therapy is a form of cancer treatment that uses radiation (strong beams of energy) to kill cancer cells or keep them from growing and dividing. Radiation therapy may be used in conjunction with surgery or chemotherapy to treat cancer.
Doctors who specialize in radiation therapy — who are called radiation oncologists— determine the optimum doses for specific types of cancer that maximize effectiveness and minimize any harm to healthy tissues. The radiation oncologist knows what type of therapy is best suited for you and your specific type of cancer.
What are the types of radiation therapy?
External radiation therapy
External beam radiation therapy (EBRT) is the most common form of radiation therapy. Beams of high-energy radiation are directed at the tumor. The position of the machine can be changed to aim the beams at different angles.
External radiation therapy is usually given five days a week for one to eight weeks, depending on the cancer. On occasion, a single treatment may be recommended. The daily treatment usually takes only a few minutes.
Types of external radiotherapy include:
- 3D conformal radiation therapy: Computed tomography (CT) scans and special computer software help create a three-dimensional computer model of the area to be treated. Treatments are more precisely targeted to the tumor, sparing surrounding normal tissue.
- Intensity-modulated radiation therapy (IMRT)/volumetric modulated arc therapy (VMAT): Intensity modulated radiotherapy provides even more precise radiation therapy. This multi-beam system varies dose intensity and narrows in on diseased cells. VMAT does this over an arc, which tends to be faster.
- Image guided radiotherapy (IGRT): Sometimes three dimensional imaging done before treatment can help ensure the best alignment to the target. This is usually done by getting a CT scan prior to each treatment. Other imaging options include X-rays, ultrasound, systems that track internal seeds and cameras that track a surface as it moves.
- Stereotactic radiosurgery/Gamma Knife radiosurgery: The Gamma Knife is considered the "gold standard" for radiation treatment for brain tumors or lesions. The Gamma Knife provides results comparable to or better than conventional surgery in many cases, without the need for a surgical incision or long recovery in the hospital. Radiosurgery is usually a single treatment, although in some cases you may have treatment broken up into a few treatments over separate days.
- Stereotactic body radiation therapy (SBRT): This type of treatment focuses high doses of intense radiation to targets outside the head. This type of treatment is usually given in one to five treatments. Sometimes special systems that control or track your breathing are necessary to further minimize radiation to the healthy parts of your body.
- Intraoperative radiation: Intraoperative radiation therapy (IORT) allows for radiation to be delivered at the time of surgery, which may help avoid the need for external radiation later. The radiation is better focused to areas that have some tumor left behind.
Internal radiation therapy
Brachytherapy and radiopharmaceuticals
In some cases internal radiation therapy is as effective in treating cancer as external. Brachytherapy involves implanting a radioactive source, or "seed," in or around a tumor. The source emits a high dose of radiation to a small area to kill cancer cells. Implants can be temporary or permanent.
- Examples of temporary brachytherapy implants include gynecologic, esophageal, orbital (eye) and coronary artery implants.
- An example of permanent brachytherapy implant is a low-dose rate prostate seed implant.
Radiopharmaceuticals are another way of delivering radiotherapy, in the form of a radioisotope bound to a carrier. Examples of radio pharmaceuticals include TheraSphere™, used to treat certain liver tumors, and Zevalin®, used to treat certain lymphomas.
What happens before radiation therapy?
Before actual radiation therapy begins your treatment has to be planned by your radiation oncologist. This step is called simulation.
It is important that you are positioned in exactly the same way each time to ensure that the correct amount of radiation is delivered to the precise area. Simulation is the treatment-planning step that customizes each person’s treatment.
The simulation procedure is performed in a room with a CT scanner. Sometimes a magnetic resonance image (MRI) is also done in the treatment position to help your doctor with planning.
Here’s what you can expect during your stimulation:
- You’re positioned in a way that can be reproduced exactly. The therapists uses molds, masks or devices to make sure your alignment is correct and to help you lie still. Harmless laser light beams also help position you accurately.
- Your skin is usually marked to help reposition you for daily treatment. These marks are usually tiny dots, each the size of a freckle.
- A contrast medium, taken by mouth or given through a vein, is sometimes needed to help improve the contrast of a scan.
- For some people, advanced cardiac breath-hold devices, such as the active breathing coordinator (ABC), may be used during a CT simulation and at treatment. These devices allow your doctor to better protect your heart from radiation during treatment. Your team will tell you how these devices work.
- The motion of your breathing with a special 4-dimensional CT scan may be done if your doctor feels that this would be best for your radiotherapy plan.
Your team will discuss with you this or any other necessary procedures at the time of simulation.
A CT scan is then performed of the area that needs treatment. Your radiation oncologist will use this CT scan to develop the best radiotherapy plan for each individual patient.
What happens during radiation therapy?
After your arrival at your therapy session you may be asked to change into a hospital gown. Then you’ll be escorted to the treatment area. Family and friends remain in the waiting area until you’re finished with your treatment.
The radiation therapists take an X-ray (called a port film) on your first day of treatment. Port films are usually taken each week to verify that you’re being positioned accurately during each treatment. (Port films don't show your progress, but are important in providing precise treatment.)
CT scans of a person in the treatment position may be taken throughout the procedure as well. This CT scanner is built into the treatment machine so this allows for 3-dimensional alignment (also known as image-guided radiotherapy).
Finally, in some situations an ultrasound may be used instead of X-ray or CT scan.
- Once the radiation therapists are certain you are positioned correctly, they start the radiation treatment. While they are not in the treatment room with you, video cameras and an intercom allow two-way communication between you and your therapists at all times.
- The radiation is "on" for only a brief time ̶ usually only one or two minutes for each position of the machine. Sometimes radiotherapy is delivered as the machine rotates over you in a continuous arc. During your radiotherapy you will need to lie as still as possible, breathe normally and relax.
- Your therapist will be in and out of the room to reposition the machine and change your position as needed. The treatment machine will not touch you and you’ll feel nothing during treatment. Total treatment time can vary from a few to several minutes.
- Once your radiation treatment is complete, your therapist will help you off the table and escort you back to the changing area or waiting room, and you can be on your way to your normal daily activities.
Risks / Benefits
How will radiation therapy affect my bladder function?
- Pain or a burning sensation when you are urinating.
- The need to urinate frequently (often in small amounts).
- Pressure or a sense of urgency to go to the bathroom, although you may have very little urine to pass.
The symptoms above may occur during the second or third week of radiation therapy. The symptoms are common and temporary, and they will gradually go away within two to four weeks of completing treatment. Occasionally, blood or mucus may appear in the urine.
How will radiation therapy affect my bowel function and bowel movements?
The lining of the bowel is very sensitive to radiation and may become inflamed, or swollen (a condition called enteritis) during treatments. Radiation may also cause an inflammation of the stomach (called gastritis) or an inflammation of both the stomach and the bowel (called gastroenteritis). Your treatments may cause you to have:
- Abdominal bloating or cramps
- Thin or loose stools
- Watery diarrhea
- Sense of urgency to have a bowel movement
The symptoms above may occur during the second or third week of radiation therapy. Occasionally, blood or mucus may appear in the stool.
How does radiation therapy cause esophagitis and mucositis?
The lining of your esophagus (food pipe) is sensitive to radiation and may become inflamed and sore during treatments (a condition called esophagitis). You may feel a burning sensation in your throat or chest, or you may feel as if you have a "lump" in your throat. You may also feel pain when you swallow.
The lining of your mouth, throat, and gums is called the oral mucosa. This lining is also sensitive to radiation, and may also become inflamed or sore during treatments (a condition called mucositis). You may have a dry mouth with thick, sticky saliva. You also may have mouth sores or discomfort when chewing or swallowing. Some patients receiving radiation treatments to the mouth may be referred to a dentist, and most patients will also be referred to a registered dietitian.
The symptoms of esophagitis and mucositis may occur during the second or third week of radiation therapy, and gradually increase during treatment. The symptoms are common and temporary - they will start going away within two or three weeks after the treatment is complete.
How will radiation therapy affect my hair?
Hair follicles are very sensitive to radiation, and your treatments may cause you to lose your hair. Most patients will notice hair loss within the treatment area about three weeks after the start of radiation.
You may want to have your hair cut short before starting radiation therapy. If you decide to wear a wig, you should shop before you have hair loss in order to match color and style.
Hair loss may be temporary or permanent, depending on the amount of radiation received and other treatments you may be having, such as chemotherapy. If your hair loss is temporary, it will probably regrow about three to six months after your treatment is complete. You may notice that the regrowth of hair is thinner or a different texture.
If you have a big beard, it is advisable to have it shaved or trimmed to allow better set-up for radiation under the mask. Ask your healthcare provider if you have any questions about this.
How will radiation therapy affect my scalp?
Your scalp (the skin over your head) is sensitive to radiation, especially after hair loss. Your skin may become pink, tender or inflamed -- much like a sunburn. After two or three weeks of treatment, your scalp may become dry and itchy. Notify your healthcare provider and he or she will give you cream to use as directed. Do not use home remedies, as they may interfere with treatment.
A dry, irritated scalp is a temporary condition and will begin to improve about two weeks after the treatment is complete. If necessary, medication can be prescribed to relieve discomfort and itching. To minimize scalp reaction throughout your treatment, follow these suggestions:
- Avoid frequent shampooing. Use a mild shampoo (such as baby shampoo) without any perfumes.
- Wash your scalp with warm water only. Avoid rubbing and DO NOT SCRATCH. Pat dry with a soft towel.
- Avoid combing or brushing your hair too much.
- Avoid using hair spray, oils or creams.
- Avoid using heat sources (including hair dryers, rollers or curling irons).
- Do not perm or color your hair until about four weeks after your treatment is complete.
- Protect your head from the sun, cold and wind by wearing a head covering (such as a cap, turban, scarf or hat made of cotton or a cotton blend).
How will radiation therapy affect my appetite?
Radiation therapy may cause you to lose your appetite. However, it is important to continue following good nutrition practices even if you don't feel like eating. Eating balanced, nutritious meals gives you the energy you need and the fuel for your body to recover from treatment and fight infection. As your radiation continues, you will likely need a softer diet and more high-calorie liquid supplements.