External radiation is usually done during outpatient visits to a hospital or treatment center. Most people get external radiation therapy over many weeks. Usually, they visit the treatment center every weekday Monday through Friday for a certain number of weeks. But some people may need to go to the treatment center twice a day for a fewer number of weeks.
Your cancer care team will help decide how much radiation is needed to treat your cancer and how often you need to get it. Three-dimensional conformal radiation therapy 3D-CRT delivers radiation beams from different directions designed to match the shape of the tumor.
This helps to reduce radiation damage to normal tissues and better kill the cancer by focusing the radiation dose on the tumor's exact shape and size. This allows the radiation oncologist to adjust the position of the patient or re-focus the radiation as needed to be sure that the radiation beams are focused on the tumor exactly and that exposure to normal tissues is limited.
This allows stronger doses to get to certain parts of the tumor and helps lessen damage to nearby normal body tissues. Helical-tomotherapy a form of IMRT that delivers radiation in a special way. For this treatment, the radiation machine delivers many small beams of radiation at the tumor from different angles around the body. This may allow for radiation to be even more precisely focused.
Photon beam radiation therapy is another name for what is usually known as external beam radiation therapy. It uses photon beams to get to the tumor but also can damage healthy tissue around the tumor.
Photons are used in treatments that are given by a machine called a linear accelerator. The photon beams are invisible and cannot be felt when they are passing through the skin to the cancer. Proton beam radiation therapy uses proton beams instead of photons or electrons. Protons are parts of atoms that cause little damage to tissues they pass through but are very good at killing cells at the end of their path. This means that proton beam radiation may be able to deliver more radiation to the tumor while reducing side effects on normal tissues.
Protons can only be put out by a special machine called a cyclotron or synchrotron. The proton beams are invisible and cannot be felt when they are passing through the skin to the cancer. Severe side effects may warrant an altered treatment plan or additional medications to reduce side effect symptoms.
The total amount of radiation the body can receive for a treated area is highly dependent on the anatomy of the specific area receiving radiation. Different tissues and organs within our body have varying sensitivity to radiation. It is important to note that advancements in radiation technology and delivery allow care providers to administer more radiation in focused areas, depending on individual patient and tumor characteristics. As a result, although people can reach the lifetime dosage limit on one area of the body, that person may still receive radiotherapy for another tumor located elsewhere.
Again, the exact length of radiation therapy depends significantly on the characteristics of the cancer. For example, a deeper tumor may require a more-focused beam for a shorter period, but a larger, shallow tumor may be treated the same focused beam for a longer period. Moreover, the location of the tumor and its proximity to other sensitive body tissues will affect radiotherapy planning and treatment. This treatment, which was developed at the turn of the 20 th century, harnesses the power of radiation to kill cancer cells while trying to avoid harming nearby healthy tissue.
Radiation therapy has come a long way since its discovery. Recent advances have allowed doctors to develop a safer and more rapid delivery method. It also means fewer trips to the cancer center. While conventional radiation therapy delivers small amounts of radiation to a patient over nine weeks, hypofractionated radiotherapy delivers larger doses, or fractions, of radiation often in about five weeks and sometimes in just a few days.
Stereotactic body radiotherapy SBRT , a precise, high-dose form of hypofractionated radiotherapy, allows physicians to treat cancer in just one to five treatments. In part, rapid radiation treatments are effective because the advanced technology helps physicists to calculate the right dose of radiation—and to precisely position the patient to receive it, so that only tumors are targeted.
The goal is to leave as many healthy surrounding cells as possible untouched by radiation. Advances include high-tech computing software, technology that helps protect neighboring body parts from irradiation and 4D scanning for treatment planning. Yu says. At Yale Medicine, radiation oncologists prescribe hypofractionation for eligible patients being treated for certain prostate, gastrointestinal, lung and breast cancers. Mayo Clinic does not endorse companies or products.
Advertising revenue supports our not-for-profit mission. This content does not have an English version. This content does not have an Arabic version. Overview Radiation therapy Open pop-up dialog box Close. Radiation therapy External beam radiation uses high-powered beams of energy to kill cancer cells. Request an Appointment at Mayo Clinic. External beam radiation therapy Open pop-up dialog box Close. External beam radiation therapy During external beam radiation therapy, you're positioned on a table and a large machine moves around you sending beams of radiation into precise points in your body.
Share on: Facebook Twitter. Show references Radiation therapy and you: Support for people with cancer. National Cancer Institute. Accessed April 2, External beam therapy EBT. Gunderson LL, et al. Intensity-modulated and image-guided radiation therapy. In: Clinical Radiation Oncology.
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