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  • Damage from radiation is determined by the radiation type, quantity, and duration, and the patient’s bodily location, underlying condition, and accumulated exposures.

  • Radiation exposure from medical diagnostic imaging has dramatically risen over the past few decades.

  • Clinicians and patients must be educated regarding the risks of medical diagnostic radiation weighed against the benefits of the medical imaging needed.

  • It is recommended that all patients keep records of their medical imaging radiation exposures, and copies of the medical images and interpretations.


Radiation exposure may occur from environmental, occupational, medical care, accidental, or intentional (terrorism) causes. With advancements in nuclear technology in the fields of medicine, energy, and industry, there is a growing risk of radiation exposure to patients, occupational workers, and the public. The extent of damage from radiation exposure depends on the type, quantity, and duration of radiation exposure; the organs exposed; the degree of disruption to DNA; metabolic and cellular function; and the patient’s age, comorbidities, and accumulated radiation exposures.

Professionals who work with radiation must have a basic understanding of radiation physics to identify risk, manage exposure, and minimize preventable spread of exposure. Radiation is energy waves or particles that travel through space. These energetic waves or particles radiate (move outward in all directions) from the source. Radiation occurs from both nonionizing and ionizing radiation sources. Nonionizing radiation is low energy, resulting in injuries related to local thermal damage (eg, microwave, UV, visible light, and radiowave). Ionizing radiation is high energy, causing bodily damage in several ways (eg, cellular disruption, DNA damage, and mutations). Ionizing radiation is either electromagnetic (x-rays and gamma rays) or particulate (alpha or beta particles, neutrons, and protons). Exposure may be external, internal, or both. Radiation exposure triggers multiple metabolic changes on the molecular and cellular levels resulting in tissue-specific damage.

The International Commission on Radiological Protection (ICRP) website provides the most up-to-date recommendations for protection against ionizing radiation ( ICRP uses the term “tissue reaction” to describe the biologic effects of radiation exposure. In radiation terminology, a rad is the unit of absorbed dose and a rem is the unit of any radiation dose to body tissue in terms of its estimated biologic effect. Roentgen® refers to the amount of radiation dose delivered to the body. For x-ray or gamma ray radiation, rems, rads, and roentgens are virtually the same. For particulate radiation from radioactive materials, these terms may differ greatly (ie, for neutrons, 1 rad equals 10 rems). In the Système International (SI) nomenclature, the rad has been replaced by the gray (Gy), and 1 rad equals 0.01 Gy = 1 cGy. The SI replacement for the rem is the Sievert (Sv), and 1 rem equals 0.01 Sv. The World Health Organization (WHO) publishes guidelines on radiation emergencies ( These guidelines include recommended interventions during the early, ...

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