How is em radiation used to treat cancer

More than half of people with cancer receive some type of radiation therapy. For some cancers, radiation therapy alone is an effective treatment. Other types of cancer respond best to combination treatments, which is using more than 1 treatment for a patient's treatment plan.

For instance, this may include radiation therapy plus surgery, chemotherapy, or immunotherapy. External-beam radiation therapy is the most common type of radiation therapy. It delivers radiation from a machine outside the body. It can treat large areas of the body, if needed. A machine called a linear accelerator, or linac, creates the radiation beam for x-ray or photon radiation therapy. This helps target the tumor while avoiding healthy tissue near the cancer cells.

Most treatments are given every weekday for several weeks. Form-fitting supports or plastic mesh masks are used for radiation therapy to the head, neck, or brain to help people stay still during treatment.

Three-dimensional conformal radiation therapy 3D-CRT. Detailed 3-dimensional pictures of the cancer are created, typically from computed tomography CT or magnetic resonance imaging MRI scans. This allows the treatment team to aim the radiation therapy more precisely. It often means that they can safely use higher doses of radiation therapy while reducing damage to healthy tissue. This lowers the risk of side effects. For instance, dry mouth is common after radiation therapy for head and neck cancer.

But 3D-CRT can limit the damage to the salivary glands that causes dry mouth. Intensity modulated radiation therapy IMRT. This is a more complex form of radiation. Proton beam therapy. This treatment uses protons rather than x-rays. A proton is a positively charged particle.

At high energy, protons can destroy cancer cells. The protons go to the targeted tumor and deposit the specific dose of radiation therapy. Unlike with x-ray beams, there is very little radiation dose beyond the tumor. This limits damage to nearby healthy tissue. Currently, doctors use proton therapy to treat certain types of cancer. This therapy is relatively new and requires special equipment. Therefore, it is not available at every medical center. Learn more about proton therapy.

Image-guided radiation therapy IGRT. This refers to the practice of using daily images of each treatment field to confirm patient positioning and make sure the target is in the field.

But cancer cells grow and divide faster than most normal cells. Radiation works by making small breaks in the DNA inside cells. These breaks keep cancer cells from growing and dividing and cause them to die. Nearby normal cells can also be affected by radiation, but most recover and go back to working the way they should. While chemotherapy and other treatments that are taken by mouth or injection usually expose the whole body to cancer-fighting drugs, radiation therapy is usually a local treatment.

Radiation treatments are planned so that they damage cancer cells with as little harm as possible to nearby healthy cells. Some radiation treatments systemic radiation therapy use radioactive substances that are given in a vein or by mouth. More than half of people with cancer get radiation therapy. Sometimes, radiation therapy is the only cancer treatment needed and sometimes it's used with other types of treatment.

The decision to use radiation therapy depends on the type and stage of cancer, and other health problems a patient might have.

Still, radiation therapy can be used to treat many types of cancer either alone or in combination with other treatments. While it's important to remember each cancer and each person is different, radiation is often the treatment of choice for the following purposes. Some cancers are very sensitive to radiation. Radiation may be used by itself in these cases to make the cancer shrink or completely go away. In some cases, chemotherapy or other anti-cancer drugs may be given first.

In such cases, radiation therapy may be used alone or in combination with surgery, chemotherapy, or both. Radiation therapy may also be given with palliative intent.

Palliative treatments are not intended to cure. Instead, they relieve symptoms and reduce the suffering caused by cancer. These scans are usually computed tomography CT scans, but they can also include magnetic resonance imaging MRI , positron emission tomography PET , and ultrasound scans.

Computed Tomography Scanner. CT scans are often used in treatment planning for radiation therapy. During CT scanning, pictures of the inside of the body are created by a computer linked to an x-ray machine. During simulation and daily treatments, it is necessary to ensure that the patient will be in exactly the same position every day relative to the machine delivering the treatment or doing the imaging. Body molds, head masks, or other devices may be constructed for an individual patient to make it easier for a patient to stay still.

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