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External Beam Radiation

External beam radiation delivers a beam of high-energy x-rays to a patient’s tumor site, in order to destroy the cancer cells. External beam radiation gets its name from the fact that the beams come from an external source (a machine called a linear accelerator) and are aimed at the site of the tumor. 

An experienced radiation oncology team at Johns Hopkins specializes in external beam radiation. As part of a larger multi-disciplinary oncology team that consultatively diagnoses and treats cancer, our team of radiation oncology specialists, including physicians, medical physicists, dosimetrists, nurses, and therapists, creates an individualized radiation therapy plan developed for a patient’s specific needs.

The safety and well being of our patients and their families are always the primary concern of every member of the radiation oncology team. We have developed a comprehensive safety program that is unique to Johns Hopkins. As an international leader in radiation safety, our standards for safety serve as an example for other academic and community-based radiation practices. Our safety program not only complies with state and national protocols, it goes well beyond those protocols by integrating innovative safety techniques developed by experts on our staff.

Through our clinical research, we offer our patients the most effective and safest therapies available, in addition to clinical trials that patients can choose to participate in.

These types of external beam radiation are used at Johns Hopkins:

To find out more about external beam radiation at Johns Hopkins, call 410-502-8000 or e-mail

Active breathing control device

The active breathing control device is not a therapy, but it is an innovative tool that is used in external beam radiation therapy for several types of cancer. Because inhaling and exhaling can move organs as we breathe, it is sometimes difficult to aim radiation at a tumor site without also involving nearby organs, particularly in the abdomen and chest areas. An active breathing control device spares nearby organs unnecessary radiation and provides clinicians with an accurate method for delivering radiation.

Image-guided radiation therapy (IGRT)

Image-guided radiation therapy (IGRT) uses frequent imaging to provide images of the cancer site. Being able to see the site provides highly precise and accurate delivery of the radiation. The radiation oncologist can create and view images of the tumor site before and during the time the radiation is delivered.

IGRT is especially useful for cancer sites in parts of the body that move (such as the lungs) or for sites near major organs and tissues that should not receive radiation (like the heart or kidneys).

Radiation oncologists at Johns Hopkins use IGRT to treat:

Intensity-modulated radiation therapy (IMRT)

Intensity-modulated radiation therapy (IMRT) is a type of external beam radiation that uses computer-controlled radiation beams in conjunction with three-dimensional computed tomography images of the tumor site and surrounding area.

IMRT delivers targeted radiation doses to the tumor site, patterned to match the shape of the tumor through modulating the intensity of the radiation beams. This technology not only means that the tumor site receives the high doses needed to destroy cancer cells, it also spares surrounding organs and tissue.

Experience with the technology as well as with the types of cancer treated through intensity-modulated radiation therapy are critical in order for the radiation oncologist and other members of the radiation oncology team to provide the most beneficial and safest radiation therapy. At Johns Hopkins, radiation oncologists, therapists, and others specialize in the use of IMRT and have treated large numbers of patients. This expertise and experience works into each treatment plan they create and the therapy sessions.

Patients who are candidates for IMRT will benefit from higher more effective radiation doses. It may require longer treatment times than external beam radiation.

Radiation oncologists at Johns Hopkins use IMRT to treat:

3D conformal radiation therapy

Technology has provided for major advances in radiation therapy at Johns Hopkins and three-dimensional (3D) conformal radiation therapy is a good example. With this therapy, digital diagnostic imaging, powerful computers, and specialized software are used to conform radiation beams to the shape of the tumor.

Before treatment begins, CT or MRI images are taken to show the anatomy of the tumor and surrounding tissues and organs. A 3D model is created and used to aim multiple radiation beams at the tumor, missing surrounding healthy areas.

Using these advanced technologies requires a great deal of experience and expertise. At Johns Hopkins, our radiation teams, including the radiation oncologists and therapists, specialize in certain types of cancers and the radiation therapies used to treat them. This specialization provides experience and expertise that is hard to find elsewhere.

Radiation oncologists at Johns Hopkins use 3D conformal radiation therapy to treat:


TomoTherapy delivers small beamlets of radiation from every point on a spiral, providing for exceptional accuracy. That accuracy is important because it ensures that radiation hits the tumor, while having less effect on surrounding organs and tissue.

Equally important is the fact that TomoTherapy also allows the radiologist to create a CT scan just prior to radiation treatment, so that the radiation treatment team can see a full three-dimensional image of a patient’s anatomy. The size, shape, and intensity of the radiation beam can be pinpointed to the exact location of the tumor.

Advanced technologies require an equally advanced radiation team. At Johns Hopkins, our radiation teams, including the radiation oncologists and therapists, specialize in certain types of cancers and the radiation therapies used to treat them. This specialization provides experience and expertise that is hard to find elsewhere.

TomoTherapy at Johns Hopkins is used to treat prostate cancer.

Volumetric modulated arc therapy (VMAT)

With volumetric modulated arc therapy (VMAT), single or multiple radiation beams sweep around the patient, greatly reducing treatment time compared to conventional radiation treatment. This new technology also offers the radiation oncologist more control and flexibility to deliver a carefully targeted dose so that only the tumor receives a high dose of radiation. Three-dimensional imaging technology aids in the precision of the radiation, giving the doctor the ability to see the tumor at the time of treatment.

If you are a candidate for VMAT radiation therapy, it’s important to keep in mind that this type of advanced technology requires experience and expertise. At Johns Hopkins, every person on the team specializes in both the cancers they treat and the technologies they use, including VMAT.

Volumetric modulated arc therapy at Johns Hopkins is used to treat liver cancer, pancreatic cancer, and prostate cancer.

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