X-Rays Made Easy

What is It?

    External radiation (also known as external beam radiation or external radiotherapy) uses high energy rays from the outside of the body to destroy a tumor within the body. The most common types of external radiotherapy use high energy X-ray beams, such as photon beams. Other types of radiation used include particle beams, such as protons or electrons. Radiation at low doses is used to take pictures inside your body as an x-ray. Higher doses of radiation are used to destroy cancer cells during cancer treatment. External radiation therapy is different from internal radiation therapy because external radiation therapy is usually given with a radiation machine called a linear accelerator to the outside of the body while internal radiation therapy is given through an injection or placing the radioactive material directly into the body.

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How Does It Work?

    Radiotherapy treatment helps to eliminate tumors by damaging the DNA within the cancer cells. The behavior of the cells is controlled by the DNA. The radiotherapy damages the DNA directly or it creates charged particles called free radicals to damage the DNA. This causes the cancer cells to stop growing or to die. The body breaks down the dead cells and gets rid of the waste. Radiotherapy may damage normal cells in the radiotherapy area but normal cells can usually repair themselves. To prevent most normal cells from being damaged, the radiation therapist may place shields against your body in order to block the radiation.

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Typical Treatment Sessions

    In most cases, the total dose of radiation and the number of treatments is based on the size and location of your cancer, the type of cancer, the reason for the treatment, your general health, and any other treatments you are getting. Most treatments take two to ten weeks and the treatment is usually given once a day for five days in a row, lasting about thirty minutes per session. The reason why most radiation therapy can’t be done all at once is because healthy cells need time to recover in between sessions. External radiation therapy is painless. However, buzzing and clicking sounds can be heard because the linear accelerator is changing positions and a strange scent that is caused by the ozone produced by the linear accelerator. Patients may also see colored lights that are used to aim the radiation.

    The radiation treatment itself only takes about five minutes, but aiming the radiation and preparing for the procedure causes the session to be extended to about thirty minutes. The people who may be involved include a radiation oncologist, radiation physicist, dosimetrist and radiation therapist. The session usually starts with you putting on a gown and lying down on a treatment table. The radiation therapist will be in the next room to control the machine, but they will be able to see, hear, and talk with you through a speaker at all times. After completing their treatment, patients will undergo evaluations, such as imaging exams and blood tests, to determine if their cancer has been eliminated or if additional treatment is required. Even if the cancer has been cured, patients continue to have periodic visits to follow up with their doctor.