Radiation Therapy

Radiation therapy is one of the most common treatments for cancer; nearly two-thirds of people with cancer will receive radiation therapy at some point during their care. The AIS Cancer Center provides life-saving radiation treatments for cancers of the breast, lung and other organs.

Our team: Experts in radiation therapy

The radiation experts and equipment at The AIS Cancer Center are among the best in the nation. Your radiation therapy is planned and supervised by a board-certified radiation oncology team, and every treatment is performed by certified radiation therapists. We’ve earned accreditation by the American College of Radiology in recognition of the expertise our radiology team delivers to patients every day.

What is radiation therapy?

Radiation therapy uses high-energy radiation to shrink tumors and kill cancer cells. Photons (X-rays or gamma rays), neutrons, and charged particles (electrons, protons, and carbon ion) are types of radiation used for cancer treatment.

  • External-beam radiation therapy: radiation is delivered from outside the body by a machine called a linear accelerator (LINAC)
  • Internal radiation therapy/brachytherapy: radioactive material is placed in the body near cancer cells

Occasionally, systemic radiation is given by pill or IV to deliver radioactive substances (iodine, strontium, samarium, and radium) to a gland (thyroid) or bone.

Why has radiation therapy been prescribed for me?

Your doctor has prescribed radiation therapy with either curative or palliative intent. Curative intent is the hope that the treatment will cure your cancer, either by eliminating a tumor, preventing cancer recurrence, or both. You may receive radiation therapy alone or in combination with surgery, in combination with chemotherapy, or in combination with both surgery and chemotherapy.

When radiation therapy is given with palliative intent, it is not intended to cure your cancer. Instead, the goal is to relieve your symptoms and reduce the suffering caused by your cancer.

How does radiation therapy kill cancer cells?

Radiation therapy damages cancer cells’ DNA, either directly or by creating free radicals that damage DNA from within the cells. When the DNA of a cancer cell is damaged beyond repair, the cell stops dividing and/or dies. Once the cancer cells die, they are broken down and eliminated by the body.

What radiation techniques are commonly used?

3-dimensional conformal radiation therapy (3D-CRT): 3D-CRT uses very sophisticated computer software and advanced treatment machines to deliver radiation to very precisely shaped target areas.

Intensity-modulated radiation therapy (IMRT): IMRT uses hundreds of tiny radiation beam-shaping devices, called collimators, to deliver a single dose of radiation. The collimators can be stationary or can move during treatment, allowing the intensity of the radiation beams to change during treatment sessions. This kind of dose modulation allows different areas of a tumor or nearby tissues to receive different doses of radiation.

Image-guided radiation therapy (IGRT): IGRT uses daily imaging scans to identify changes in a tumor’s size and location and allow your position or the planned radiation dose to be adjusted as needed. Repeated imaging can increase the accuracy of your radiation treatments and may allow less tissue to be treated than originally planned, decreasing the total radiation dose to normal tissue.

Stereotactic radiosurgery (SRS): SRS can deliver one or more high doses of radiation to a small tumor or tumors in the brain or spinal cord. SRS requires the use of a head frame, mask or other devices to immobilize the patient during treatment to ensure that the high dose of radiation is delivered accurately.

Stereotactic body radiation therapy (SBRT): SBRT is often used to treat small tumors in the lungs or other organs (liver, adrenal glands and spine). It delivers two or more high doses of radiation to these small tumors.

Particle beams: Electron beams are negatively charged particles used to irradiate superficial tumors, such as skin cancer or tumors near the surface of the body. Proton beams and carbon ion beams are positively charged particles that can be used for external beam radiation therapy.

How will my radiation therapy be planned?

A radiation oncologist develops a unique treatment plan for you, beginning with simulation. During simulation, you are given imaging scans to reveal the exact location of your tumor and the normal tissue around it. Computed tomography scans (CT) are often used for this. During a CT scan, a computer linked to an X-ray machine creates detailed pictures of the inside of your body. These CT scans may then be combined with previously performed diagnostic imaging (MRI, PET/CT) to help your doctor develop your treatment plan.

During simulation, and later during treatment, you must be in exactly the same position every time for the machine doing your imaging or delivering treatment. Your treatment team may use body molds, head masks, special positioning boards, or other devices to make sure you’re positioned accurately. You may be given temporary skin marks and small ink tattoos to help with this precise positioning.

After simulation, your radiation oncologist determines:

• The exact area that will be treated

• The total radiation dose that will be delivered to the tumor/target

• How much radiation dose will be allowed for the normal tissues around the tumor

• The optimal beam angles or delivery technique for the delivery of the radiation dose

How is the radiation dose measured?

Radiation doses for cancer treatment are measured in a unit called a gray (Gy), which is a measure of the amount of radiation energy (1 joule) absorbed by 1 kilogram of human tissue. Different doses of radiation are needed to kill different types of cancer cells.

What factors are considered in designing my radiation treatment?

Radiation can damage some types of normal tissue more easily than others. For example, the reproductive organs (testicles and ovaries) are more sensitive to radiation than bones. Your radiation oncologist takes all of this information into account during your treatment planning. The area selected for treatment usually includes the whole tumor plus a small amount of normal tissue surrounding the tumor. The normal tissue is treated for two main reasons:

• To take into account body movement from breathing and normal movement of the organs within the body, which can change the location of a tumor between treatments

• To reduce the likelihood of tumor recurrence from cancer cells that have spread to the normal tissue next to the tumor (called microscopic local spread)

Why is radiation therapy given in several small doses?

When you receive most types of external-beam radiation therapy, you usually have to travel to the hospital or outpatient facility for up to five days a week for several weeks. You’re given one dose (a single fraction), or occasionally two doses, of the total planned dose of radiation each day. There are two main reasons for this:

• To minimize the damage to normal tissue

• To increase the likelihood that cancer cells are exposed to radiation at the points in the cell cycle when they are most vulnerable to DNA damage

Can I have radiation therapy more than once?

If an area of your body has previously been treated with radiation therapy, you may not be able to have radiation therapy to that area a second time. This depends on how much radiation was given during the initial treatment. If one area of your body has already received the maximum safe lifetime dose of radiation, another area might still be treated with radiation therapy if the distance between the two areas is large enough.

A referral is necessary for radiation treatment. For more information, call us at (661) 323-4673 or complete our appointment request form.


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