What is radiation?

Radiation therapy consists of a high energy x-ray beam powerful enough to kill cancer cells that is directed at the tumor and surrounding tissues. It is usually limited to the area of the tumor and sometimes the surrounding lymph nodes. Like chemotherapy, radiation damages rapidly dividing cells. It kills cells primarily by damaging the DNA and also by producing oxidative particles that damage the nearby cells. Unlike chemotherapy, which goes throughout the body, radiation only impacts the tissues at which it is aimed.

Radiation can be given before or after surgery. In breast cancer the reason to give radiation before surgery is to make the tumor smaller and easier to resect. It is given after surgery to kill any microscopic cells that might have been left behind.

Radiation can be delivered externally or internally. Radiation is delivered externally by a linear accelerator which generates high energy x-rays and electrons targeted at the cancer and is called external beam radiation therapy. Radiation is delivered internally by placing the radiation inside the body directly against or inside the cancer which is called brachytherapy.

Though you may be the least familiar with radiation as far as cancer treatments go, about half of all cancer patients get radiation at some point. The radiation used in cancer treatment is of much higher energy than that used in chest x-rays or CT scans. This underscores the need to direct it precisely at the target tissues. Patient positioning and immobilization as part of the planning process are therefore critical to successful radiation treatment.

External Beam Radiation

The most common way to deliver radiation is with external beam therapy. This means that a beam of x-rays is generated by the linear accelerator and aimed precisely at the treatment area in accordance with extensive planning described below. A portion of the machine called the gantry will rotate around the table on which you are lying to deliver the radiation from multiple angles.

Standard external beam radiation involves aiming the radiation from two to four directions. When CT treatment planning is utilized, often more beams are used. There are several terms used to describe three dimensional treatment including 3D conformal radiation therapy, intensity modulated radiation therapy (IMRT), and volumetric modulated arc therapy (VMAT).

These three types of treatment as listed represent increasing levels of complexity and precision. While not all tumors require the precision of VMAT or can even be treated that way, your radiation oncologist should be able to explain why he or she is choosing one treatment planning method over another.

Brachytherapy

Brachytherapy is a term derived from the Greek word brachy and means short distance. In radiation therapy this means placing a radioactive source directly next to or inside of a tumor.

This has long been a mainstay of treatment in gynecologic tumors and head and neck cancers, but more recently, brachytherapy is also being used in the treatment of breast and prostate cancer.

For breast cancer, brachytherapy is called accelerated partial breast irradiation (APBI). While most women who have small breast cancers are candidates for standard external beam radiation therapy after a lumpectomy, some women may qualify for brachytherapy as an alternative treatment option. Standard external beam treatment for breast cancer is about a six week course of treatment. Most breast brachytherapy is done over the course of a week with two treatments a day.

At the time of surgery or shortly thereafter either a balloon or expandable struts are placed inside the breast where the tumor was. This space is referred to as the tumor bed. The twice a day radiation treatments consist of inserting a powerful radioactive seed into one or more catheters (hollow plastic tubes) that run through the balloon or along the struts.

The seed is moved to various positions over the course of several minutes to deliver radiation to the tumor bed and a small margin of normal tissue beyond the bed. One of the benefits to this treatment in addition to the shorter overall treatment duration is that the radiation is limited to the tumor bed and just beyond. The rest of the breast, skin, lungs, and heart get almost no radiation.

How to prepare for your first visit

Your first visit will likely consist of a consultation with the radiation oncologist. If at all possible, you should have someone with you who can take notes about the discussion. The radiation oncologist will gather all of the information about your breast cancer and the treatment you have had to date. From this information he or she will determine if you need radiation. Keep in mind that there are several treatment options for early stage breast cancer and radiation may not be needed for some patients.

If you do need radiation, the radiation oncologist will explain how long treatment will take and the potential side effects of treatment. Usually the radiation oncologist will meet with you once a week during treatment to assess your progress. This will also give you an opportunity to ask questions that you might not have been able to ask on the first visit. Generally, it takes some time for all the facts to sink in, and you may come up with questions as the treatment progresses.

The Planning Process

The first step in the treatment planning is to do the simulation. In this step, you will be asked to lie on a treatment table and a radiation therapist will place your body in a position that will be best for your radiation treatment. You may even have a special mold made for your body to reliably reproduce this position and prevent unintended movement on your part. The correct positioning is important to give access to the area that needs to be treated and to protect normal tissues.

During the simulation process you will likely get some markings and tiny tattoos. These are used to set you up in exactly the same position every day.

Today most radiation oncology centers have the ability to do a treatment planning CT. This allows your team to see your body in three dimensions and deliver the radiation from multiple angles. The radiation oncologist, radiation physicist, and dosimetrist are all involved in planning the delivery of the radiation so that the target tissues receive a full dose and the dose to normal tissues is minimized.

The Treatment Process

Once the treatment planning has been completed, you will be scheduled for your regular treatment. The treatments usually take 10 to 15 minutes and are given Monday through Friday. The therapist or nurse will likely show you the changing area and instruct you to change into a gown before each treatment.

For your first treatment and at various points during your treatment, your positioning will be checked with imaging to make sure the radiation is being aimed exactly where it is supposed to be. The radiation therapists will position you on the treatment table and make minor adjustments every day before your treatment. They will ask you to lie very still. It is important that you tell them if you are uncomfortable since any movement during treatment will compromise the precise delivery of your radiation dose. If you are cold, ask for a warm blanket. If you are in pain, let them know so that they can adjust your positioning. If you would like some music, just ask.

Once you are in the correct position, the radiation therapists will walk out of the room. They deliver the treatment from a station just outside of the room. You are still being watched on camera and they can hear you. They can speak to you over an intercom.

Some patients get anxious about being left in the room alone, but rest assured, you are being closely monitored the entire time. If you have problems with anxiety or claustrophobia, do not hesitate to discuss this with the therapists or the radiation oncologist.

Treatments usually consist or two or more fields so the therapists will likely re-enter the room and move the gantry to treat the next field. The gantry is the part of the machine that hangs over the table and moves around you. For some types of radiation delivery, the gantry moves during the treatment. Don’t be alarmed and just try to remain still.

Preparing for Brachytherapy

The planning process for brachytherapy will involve a CT simulation. During the planning process, the radiation physicist determines the amount of time the radiation pellet will remain in each position in the catheter to deliver the prescribed dose. You may have a CT each day before treatment.

The therapist will connect the catheter to the radiation delivery machine, and then you will be left alone in the room just as with external beam radiation. You are being closely monitored, and the therapists can see and hear you at all times. Be sure to let your therapists know if you need a blanket or music to make you more comfortable.