An Introduction to Radiation Therapy
What is radiation therapy?
Radiation is a special kind of energy carried by waves or a stream of particles. It can come from radioactive substances and special machines. There are many different levels of radiation energy. We have all been exposed to some low levels of radiation energy, such as radiation from the sun or radiation used to make a chest x-ray or mammogram. When radiation energy is used at high levels, it can treat cancer and other illnesses. The use of high-energy rays or particles to treat a disease is called radiation therapy.
Cancer is a tumor, or an overgrowth of abnormal cells. These cells grow by multiplying or dividing to rapidly make new tumor cells. The ability to multiply without limits, grow quickly, and grow into surrounding normal tissues makes cancer cells different from normal cells. There are many different types of cancer. Each type of cancer is unique in how it grows and how it responds to treatment. One way to stop the cancer from growing is to interfere with the cancer cell’s ability to multiply. Radiation, used at high doses, causes changes in the cancer cell that stop the cell’s ability to multiply and eventually kills the cancer cell.
Radiation therapy is one of four approaches to the treatment of cancer. The other three are surgery, chemotherapy, and biological therapy. Since each type of cancer is unique, research has helped physicians determine which treatment or combination of treatments is appropriate for each type of cancer. Radiation therapy may be used alone or in combination with surgery, chemotherapy, and/or biological therapy. Radiation therapy may be used in an attempt to cure the cancer or to treat unpleasant symptoms the cancer is causing such as pain or bleeding. The most common types of cancer that radiation therapy is used for are brain tumors, head and neck cancers, lung cancer, breast cancer, prostate cancer, skin cancer, rectal cancer, cervix and uterine cancers, lymphoma, and sarcoma.
How is radiation therapy given?
Radiation therapy for the treatment of cancer may be given in two different ways. External beam irradiation is the most common method. The radiation is delivered to a specific area of the body using a large machine similar to an x-ray machine. The treatment is given each day, Monday through Friday, for 1 to 8 weeks depending on the type of cancer and the reason for the treatment. The treatment may be given once a day, twice a day, or as many as three times a day for certain cancers.
The other method of delivering radiation treatment is called brachytherapy. In this method, a source of radiation in the shape of needles or seeds is implanted in the body. This treatment is often given before or after external beam irradiation as a way of increasing the radiation dose to only the tumor. Brachytherapy is often used in cervix, uterine, and prostate cancers, some head and neck cancers, and sarcomas. The implants are placed in the body while the patient is anesthetized in the operating room. Some of the implants stay in place permanently, whereas others are removed after 2 or 3 days.
Who gives the radiation therapy?
At the University of Florida a team approach to treating patients has been developed. The team consists of a radiation oncologist, physicist, dosimetrist, radiation therapists, and a nurse. The radiation oncologist is a physician who has completed a residency in radiation oncology. The radiation oncologist is responsible for determining the role of radiation therapy in a patient’s care, planning the treatment, and evaluating the patient for the response to the treatment. The physicist and dosimetrist help the radiation oncologist with the treatment plan. They are responsible for designing the immobilization devices, generating the computer plan, calculating the dose of radiation, and conducting weekly checks to make sure the treatment is being given accurately. The radiation therapists are responsible for the simulation procedure and the daily treatments. Each day they assist the patient into the treatment position, assure that the radiation field is accurate, and deliver the treatment. They work closely with the radiation oncologist to identify any shifts or changes in the field before the daily treatment.
The nurses are responsible for coordinating all of the patient’s care both during and after treatment. They assist the radiation oncologist with making appointments, evaluating symptoms related to the treatment, and making referrals for social services and nutritional evaluations as needed. In addition, they are available to provide patient and family education about the treatment, side effects, medications, and long-term planning. Additional support staff are the social worker, dietician, secretaries, clerical staff, data manager, and research staff. Since our department is part of the University of Florida College of Medicine, a resident (a physician obtaining advanced training in radiation oncology) also participates in the patient’s care.
What are the steps of treatment?
Consultation. The first step is a visit to the radiation oncologist. During this visit, the radiation oncologist reviews all of the patient’s records, pathology reports, and x-ray films and performs a physical examination. At the conclusion of the exam, he or she discusses the recommendations for radiation treatment with the patient and family. Several appointments are made for the patient so that a plan for the radiation treatment can be developed. These appointments include one or two planning sessions called simulations and a date to start treatment.
Simulation. The second step is an appointment for simulation. During this appointment, the patient is placed in a position on a flat x-ray table that gives the best access to the area that needs to be treated. This is called the treatment position. To make sure that the radiation treats the same precise place in the body each treatment day, an immobilization device such as a mold or mask may be designed to help the patient lie in the same position every day. For example, a mask may be required for treatment of the head and neck region. A mold may be used to treat an area of the leg or arm. Immobilization devices are not a necessity for all patients.
While the patient lies in the treatment position, x-rays or a CT scan is performed of the area to treated. The radiation oncologist uses these x-rays to design the exact size and area that the radiation is to treat.
It may be necessary in some cases to use contrast material. For example, if a patient’s pelvis is to be treated, contrast material is inserted into the rectum and bladder so that these organs are visible on the x-ray film. In other cases, small pieces of wire are placed on the skin to enable the radiation oncologist to see certain landmarks that would not otherwise show up on the x-rays. Once all the x-rays are obtained, any contrast material and/or the pieces of wire placed on the skin are removed.
Several small marks are left on the skin to help identify the area to be treated. These marks are used to confirm the treatment plan during the next visit and on each treatment day.
Treatment planning. The next step involves only the radiation oncologist, physics staff, and dosimetrists. The radiation oncologist, using the x-rays obtained during the simulation, designs the treatment field. The physics staff designs special shielding blocks or plans to shape the radiation beam to the treatment field and help shield the normal tissue from the radiation beam. In addition, special computer plans are developed by the dosimetrist that help the radiation oncologist develop a plan of treatment to give the best radiation dose distribution to the treatment field selected.
Depending on the treatment plan, some patients return for a second simulation appointment. During this appointment the shielding blocks are placed in the head of the machine, and an x-ray is taken. The radiation oncologist compares this x-ray with the simulation film (or planning films) to assure accuracy. During this visit, additional lines are drawn on the skin to outline the exact treatment field. These lines are used by the radiation therapists to assure accuracy each day of treatment and are to remain on the skin throughout the course of treatment.
Start of treatment. Treatment can now start. The radiation therapists are responsible for positioning the patient and delivering the radiation dose. On the first day of treatment, the patient is placed in the treatment position. The therapist uses several techniques to accurately reproduce the treatment. These include laser lights, field lights, and SSD measurements. The laser lights are used to make sure the patient is level and straight on the table. The field light corresponds to the skin marks, and the SSD is the number that represents the distance from the source of radiation to the skin. Once everything is in place, the therapists leave the room. No one is allowed to stay in the room with the patient during the actual irradiation. The patient is observed on TV monitors outside the room and also can speak to the therapists if necessary. The treatment itself is very short. The patient is usually in the room less than 30 minutes a day, and most of this time is spent getting the treatment fields accurately positioned.
Several x-ray films are taken on the first day of treatment and weekly thereafter or if changes of the treatment field are necessary. These films are not used to determine if the cancer has decreased in size, but rather are compared with the initial planning films to make sure that the fields have not shifted. On approval of the treatment x-rays, and with the patient’s permission, permanent small tattoos (approximately the size of a pinhead) are placed on the skin in 5 or 6 places to mark the corners and center of the treatment field. These tattoos are necessary for two reasons: (1) if the skin markings come off during the course of treatment, the field can be reproduced by locating the tattoos; and (2) if in the future further treatments are required, the previous fields can be located and overtreatment can be avoided.
Radiation treatments do not hurt, but do require cooperation of the patient in remaining completely still. When a child is the patient, safety straps must be used. They are not tight; they are just a preventive measure. Parents must remain outside the room but can talk to the child on the intercom. We recommend that the child bring a favorite tape to listen to while undergoing treatment.
What happens on a typical treatment day?
Each day, the patient checks in with the receptionist at the scheduled appointment time for treatment. A radiation therapist escorts the patient into the treatment room. Clothes that cover the treatment fields are removed. The patient is positioned on the treatment table in the treatment position. Sheets and blankets are available to provide privacy and comfort. The shielding block for the first treatment field is placed in the machine. The therapists confirm the position, touch up the lines that outline the field, and then leave the room. The machines are turned on for the appropriate treatment dose and time.
Once the treatment is completed, the therapists position the machine for the next treatment field, and the process is repeated until all fields have been treated. After all fields are treated and treatment is complete for the day, the patient may dress and go home.
Once a week, the radiation oncologist meets with the patient to determine how well the patient is reacting to the treatment and to provide answers to questions from the patient or family. However, if the patient develops a new problem during the week, the radiation oncologist, nurse, or another designated person is available to care for the patient.
What are the side effects of radiation therapy?
The side effects of radiation therapy depend on the area of the body that is exposed to the radiation as well as the dose given. There are two side effects that are common among most patients: fatigue and skin irritation. The fatigue usually begins after several weeks of treatment and may not resolve for 2 to 3 months after treatment.
Skin irritation occurs on the area of the body being treated, whether the radiation is given superficially or deeply into the body, and depends on the dose of radiation given. The skin becomes red, dry, and itchy. Occasionally the skin becomes blistered. The radiation oncologist provides the patient with instructions for cleaning the skin and treating the skin irritation when this occurs.
A number of other side effects are possible and depend on where the radiation is given. Hair loss may occur in the field of radiation. If radiation is not being given to the head, however, hair loss from the scalp does not occur. If the treatment is to the mouth, throat, or neck, side effects may include a sore mouth, dry mouth, and difficulty swallowing. Treatment to the lung may cause irritation of the lung and esophagus, causing coughing and increased sputum production as well as some difficulty swallowing. Treatment to the abdomen may cause nausea, vomiting, and diarrhea. Treatment to the pelvis may cause nausea, vomiting, and diarrhea as well as rectal, bladder, and vaginal irritation.
Most of the side effects caused by radiation therapy resolve within 4 to 6 weeks of completing treatment. Long-term effects of treatment may include some permanent changes in the color and elasticity of the skin in the treatment field. Other changes depend on the site of treatment and the dose. These effects are discussed by the radiation oncologist before the start of any treatment.
Responsibilities of the patient and family
To avoid delays in treatment and potential problems, the patient and family also have several responsibilities. The first is to provide the radiation oncologist with an accurate and detailed medical history, medication list, and allergy list. If the patient has received any treatments for cancer in the past, including radiation, chemotherapy, surgery, or biological therapy, it is important to provide the radiation oncologist with the name, address, and phone number of the appropriate physician(s). Delays in obtaining outside records can delay the start of treatment.
The second responsibility is a commitment to the treatment plan. This includes arriving on time for appointments, not removing the marks on the skin, and reporting side effects or other problems that the patient may experience. The earlier that a new problem is identified, the sooner it can be managed and, we hope, solved. This includes problems with insurance, housing, transportation, or employment in addition to physical side effects related to the treatment. It is also important to try to follow recommendations for taking medications and nutritional supplements. Following these recommendations can help avoid a break in the treatment course, which can have a negative impact on the desired outcome.