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Frequently Asked Questions

Find answers below to the questions we hear most often, such as what radiation therapy involves and what ASTRO does. For more information, visit RT Answers for brochures, videos and other patient-friendly information, or contact ASTRO's media relations team.


What is ASTRO?

The American Society for Radiation Oncology (ASTRO) is the largest radiation oncology society in the world, with 10,000 members who specialize in treating patients with radiation therapies. As the leading organization in radiation oncology, biology and physics, ASTRO is dedicated to improving patient care through education, clinical practice, advancement of science and advocacy. Read more about ASTRO's history.

Who are ASTRO’s members?

ASTRO’s members are physicians, nurses, biologists, physicists, radiation therapists, dosimetrists and other health providers and scientists who specialize in treating patients with radiation therapies. ASTRO’s membership consists of health care professionals from community medical centers as well as academic research facilities. Read more about ASTRO member demographics.

How does ASTRO promote radiation oncology?

Within the field of radiation oncology, ASTRO promotes scientific and technological advancements by sponsoring meetings for oncologists and other health care providers, publishing three peer-reviewed research journals, and providing educational and professional development opportunities for its members.

Within the medical community, ASTRO fosters cooperative efforts between radiation oncologists, medical oncologists, surgeons and other physicians to provide effective treatment through a team approach.

ASTRO also publishes educational materials to keep patients and the general public informed about radiation therapy as a treatment option. ASTRO also works with the media to promote accurate articles on scientific breakthroughs involving radiation therapies and is a major contributor in the development of legislation and regulations affecting patient care.

About Radiation Therapy

What is radiation therapy?

Radiation therapy, also called radiotherapy or irradiation, is the careful, therapeutic use of high-energy waves or streams of particles called radiation. At low doses, physicians and radiologists use radiation for diagnostic purposes to take internal pictures (X-rays) of the body. Radiation oncologists, highly trained cancer treatment specialists, use higher doses of radiation to treat cancer and other diseases. Patients benefit from this type of treatment because the high-energy waves used in radiation therapy are able to kill fast-growing cancer cells while minimizing damage to healthy tissue.

Who administers radiation therapy?

A specially trained physician, called a radiation oncologist, is responsible for prescribing a patient’s radiation therapy treatment. The radiation oncologist works with a specially trained team of health care professionals, including radiation oncology nurses, medical physicists, dosimetrists and radiation therapists. This team works under the direction of the radiation oncologists to ensure high quality care for patients. Radiation oncologists are different from radiologists, who use radiation to diagnose disease and detect other health problems.

How do patients receive radiation therapy?

Depending on the location of the cancer, patients can receive radiation therapy either externally or internally. External radiation is created and delivered by special machines, typically linear accelerators. With external radiation, a machine directs the high-energy waves at the cancer and a small amount of the healthy tissue surrounding it. When internal radiation is used, the radiation source is placed inside the body. The radiation source can be delivered by an intravenous injection or by temporarily or permanently inserting radioactive pellets or wires directly into the tumor. The insertion of a radioactive substance into a tumor is called brachytherapy.

How long does radiation therapy take?

With external radiation, the total dose of radiation needed to kill the cancer cells is more than most patients can handle at one time so the dose is typically spread out over a series of daily outpatient treatments. Each treatment is brief and the radiation therapy machine will turn on and off throughout the treatment. The actual treatment is painless, but there can be side effects depending on what part of the body is being treated. The total number of treatments varies with the type of cancer and the extent of disease and can range from one to forty treatments. With internal radiation, some brachytherapy treatments are given more than once depending on the type and the extent of the patient’s cancer. Some types of brachytherapy are given on an outpatient basis while others require admission to a hospital for one or more days.

About the Radiation Oncology Team

Who are the members of the radiation oncology team?

The radiation oncology team is made up of radiation oncologists, radiation oncology nurses, medical physicists, dosimetrists, radiation therapists and social workers. All states require continuing medical education for these professionals, and many states have programs to regularly inspect the radiation therapy equipment.

What does each team member do?

  • A radiation oncologist is the physician responsible for the radiation therapy given to a patient. Patients are typically referred to a radiation oncologist by another cancer physician or by a primary care doctor. After evaluating the patient, reviewing tests and talking with the patient’s other cancer physicians, the radiation oncologist prescribes a treatment plan for the patient. Throughout the treatment, the radiation oncologist monitors the patient’s condition to maintain high-quality care. The radiation oncologist also works to identify and treat any side effects from the treatments.Radiation oncologists are different from radiologists, who use radiation to diagnose disease and detect other health problems.
  • The specially trained radiation oncology nurse helps educate patients about the side effects of radiation therapy and monitors their progress throughout treatment. The nurse often acts as a liaison between the radiation oncologist and the patient to increase the overall efficacy of the treatments and ensure good communication between all team members.
  • The medical physicist is a highly trained physicist who works with the radiation oncologist to help plan the treatments. The medical physicist also maintains the radiation therapy equipment to ensure that the correct dose of radiation is delivered each time. They are often involved in the quality control process and monitor the accuracy of the treatments.
  • The medical dosimetrist is a specially educated radiation worker who works with the radiation oncologist and medical physicist to create the treatment plan. The dosimetrist typically electronically calculates the precise amount of radiation to be delivered to the patient.
  • The radiation therapist is a special radiation worker who operates the external radiation therapy equipment and assists the radiation oncologist with the handling of the internal radiation therapy equipment. They are often involved in the quality control process and work with the other team members to monitor the patient’s condition.

How do you become a radiation oncologist?

To become a radiation oncologist, you must complete four years of college, four years of medical school, one year of general medical training and four years of residency or specialty training in radiation oncology. In order to become board-certified in radiation oncology, you must pass a series of exams administered by the American Board of Radiology.

About the ASTRO Annual Meeting

What is ASTRO's Annual Meeting?

ASTRO’s Annual Meeting is the nation’s leading scientific meeting about advances in radiation oncology.

These meetings highlight the best and most up-to-date research in radiation oncology. Meetings also provide ASTRO members and other attendees with education and professional development opportunities, including continuing medical education (CME) credits for physicians, continuing education units for nurses and medical dosimetrists, and CAMPEP credits for physicists.

The Annual Meeting is held concurrently with annual gatherings of the American Society of Radiologic Technologists (ASTR) and the Society of Radiation Oncology Administrators (SROA).

When and where is the next ASTRO Annual Meeting, and who attends the meeting?

ASTRO’s 66th Annual Meeting will be held  September 29-October 2, 2024 at the Walter E. Washington Convention Center in Washington, DC. The theme of the meeting is “Targeting Provider Wellness for Exceptional Patient Care.” Learn more about the upcoming Annual Meeting.

The ASTRO Annual Meeting attracts thousands of attendees including oncologists from all disciplines, medical physicists, dosimetrists, residents, radiation therapists, radiation oncology nurses and nurse practitioners, biologists, physician assistants, practice administrators, industry representatives and other health care professionals from around the world.

ASTRO Annual Meetings also include a press program, with news briefings that highlight a select group of top-rated studies from the meeting. View a recap of the most recent press program, including recordings and photos from the news briefings.

About Cancer

More than 2 million new cancer cases will be diagnosed in 2024, according to the American Cancer Society. Over the course of a lifetime, approximately 42 out of 100 men and 40 out of 100 women will develop cancer. About 88% of all cancers are diagnosed in patients age 50 or older.

Cancer is the second leading cause of death among all Americans, exceeded only by heart disease. Approximately 611,720 Americans are expected to die of cancer in 2024 - roughly 1,680 people per day.

The death rate from cancer, however, dropped 33% from its peak in 1991, due mainly to reductions in smoking and advances in treatment and detection. An estimated 18+ million living adults and children in the U.S. have a history of invasive cancer.

Skin cancer is the most commonly diagnosed cancer in the United States. The next most common cancer for women is breast cancer, followed by lung cancer and colorectal cancer. The next most common cancer for men is prostate cancer, followed by lung cancer and colorectal cancer. Among children age 14 and younger, the most common cancers are leukemias.

Nearly $209 billion was spent on cancer-related health care in the U.S. in 2020, the most current data available. This total includes costs paid by employers, insurance companies, public programs like Medicare and Medicaid, patients with cancer and their caregivers — including more than $16 billion spent by patients out-of-pocket for cancer treatment.

Content last updated 2/13/2024.

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