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Radiation Safety
Chad Davis, MD; Brandt C. Wible, MD
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KEY FACTS

  • Terminology

    • Preprocedure

      • Post Procedure

        TERMINOLOGY

        • Definitions

          • As low as reasonably achievable (ALARA): Effort to maintain exposures to radiation as far below dose limits as is practical
        • Radiation Basics

          • Absorbed dose: Amount of energy absorbed by matter
            • Measured in gray (Gy), a Standard International (SI) unit
            • 1 Gy = 1 joule/kg
            • Radiation-absorbed dose (rad); outdated unit
              • 0.01 Gy = 1 rad
          • Equivalent dose: Radiation dose weighting based on harmful biologic effect of dose
            • Measured in sieverts (Sv), an SI unit
            • 1 Sv = 1 joule/kg
            • Sv and Gy are not interchangeable
            • 1 Sv = 100 roentgen equivalent man (rem), a non-SI unit
              • 1 rem increases chance of cancer by 0.055% over lifetime
              • Millirem (mrem): Often used to describe medical device dosage
                • Denote stochastic biologic effects of ionizing radiation
                • 5000 mrem = maximum allowed effective dose to physician body/year
                • 300 mrem = typical natural background radiation/year
          • Effective dose: Equivalent dose accounting for tissue/organ sensitivity and specific damage from radiation
            • Measured in Sv (SI) or rem (non-SI)
          • Effects of ionizing radiation
            • Deterministic
              • Effects exhibit threshold; below threshold, effect is not observed
              • Severity of effect increases with increasing dose above threshold (e.g., radiation-induced hair loss, skin injury, cataracts, sterility)
            • Stochastic
              • Probabilistic; nondeterministic health effects
              • Probability of event increases linearly with increasing dose without threshold, but severity of effect is constant (e.g., cancer)
            • Biologic effect of radiation doses
              • 10 Sv: High probability of death within days/weeks
              • 1 Sv: 5.5% ↑ probability of cancer during lifetime
              • 100 millisieverts (mSv): 0.5% probability of cancer during lifetime
              • Radiation risk is inversely related to patient age
              • Sequela of radiation exposure is often delayed, frequently weeks to months after exposure

        PREPROCEDURE

        • Preprocedure Imaging

          • Getting Started

            PROCEDURE

            • Ways to Reduce Patient Dose in Fluoroscopy

              • Ways to Reduce Operator Dose in Fluoroscopy

                • Ways to Reduce Patient Dose in CT

                  • Pregnant Patient Guidelines

                    POST PROCEDURE

                    • Expected Outcome

                      • Things To Do

                        Selected References

                        1. United States Nuclear Regulatory Commission. NRC Regulations (10 CFR). Part 20: Standards for protection against radiation. Published June 31, 2015
                        2. Authors on behalf of ICRP et al: ICRP publication 118: ICRP statement on tissue reactions and early and late effects of radiation in normal tissues and organs--threshold doses for tissue reactions in a radiation protection context. Ann ICRP. 41(1-2):1-322, 2012
                        3. Bushberg JT: The Essential Physics of Medical Imaging. Philadelphia: Lippincott Williams & Wilkins, 2012
                        4. Smith JC et al: Ultra-low-dose protocol for CT-guided lung biopsies. J Vasc Interv Radiol. 22(4):431-6, 2011
                        5. Stecker MS et al: Guidelines for patient radiation dose management. J Vasc Interv Radiol. 20(7 Suppl):S263-73, 2009
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                        References
                        Tables

                        Tables

                        KEY FACTS

                        • Terminology

                          • Preprocedure

                            • Post Procedure

                              TERMINOLOGY

                              • Definitions

                                • As low as reasonably achievable (ALARA): Effort to maintain exposures to radiation as far below dose limits as is practical
                              • Radiation Basics

                                • Absorbed dose: Amount of energy absorbed by matter
                                  • Measured in gray (Gy), a Standard International (SI) unit
                                  • 1 Gy = 1 joule/kg
                                  • Radiation-absorbed dose (rad); outdated unit
                                    • 0.01 Gy = 1 rad
                                • Equivalent dose: Radiation dose weighting based on harmful biologic effect of dose
                                  • Measured in sieverts (Sv), an SI unit
                                  • 1 Sv = 1 joule/kg
                                  • Sv and Gy are not interchangeable
                                  • 1 Sv = 100 roentgen equivalent man (rem), a non-SI unit
                                    • 1 rem increases chance of cancer by 0.055% over lifetime
                                    • Millirem (mrem): Often used to describe medical device dosage
                                      • Denote stochastic biologic effects of ionizing radiation
                                      • 5000 mrem = maximum allowed effective dose to physician body/year
                                      • 300 mrem = typical natural background radiation/year
                                • Effective dose: Equivalent dose accounting for tissue/organ sensitivity and specific damage from radiation
                                  • Measured in Sv (SI) or rem (non-SI)
                                • Effects of ionizing radiation
                                  • Deterministic
                                    • Effects exhibit threshold; below threshold, effect is not observed
                                    • Severity of effect increases with increasing dose above threshold (e.g., radiation-induced hair loss, skin injury, cataracts, sterility)
                                  • Stochastic
                                    • Probabilistic; nondeterministic health effects
                                    • Probability of event increases linearly with increasing dose without threshold, but severity of effect is constant (e.g., cancer)
                                  • Biologic effect of radiation doses
                                    • 10 Sv: High probability of death within days/weeks
                                    • 1 Sv: 5.5% ↑ probability of cancer during lifetime
                                    • 100 millisieverts (mSv): 0.5% probability of cancer during lifetime
                                    • Radiation risk is inversely related to patient age
                                    • Sequela of radiation exposure is often delayed, frequently weeks to months after exposure

                              PREPROCEDURE

                              • Preprocedure Imaging

                                • Getting Started

                                  PROCEDURE

                                  • Ways to Reduce Patient Dose in Fluoroscopy

                                    • Ways to Reduce Operator Dose in Fluoroscopy

                                      • Ways to Reduce Patient Dose in CT

                                        • Pregnant Patient Guidelines

                                          POST PROCEDURE

                                          • Expected Outcome

                                            • Things To Do

                                              Selected References

                                              1. United States Nuclear Regulatory Commission. NRC Regulations (10 CFR). Part 20: Standards for protection against radiation. Published June 31, 2015
                                              2. Authors on behalf of ICRP et al: ICRP publication 118: ICRP statement on tissue reactions and early and late effects of radiation in normal tissues and organs--threshold doses for tissue reactions in a radiation protection context. Ann ICRP. 41(1-2):1-322, 2012
                                              3. Bushberg JT: The Essential Physics of Medical Imaging. Philadelphia: Lippincott Williams & Wilkins, 2012
                                              4. Smith JC et al: Ultra-low-dose protocol for CT-guided lung biopsies. J Vasc Interv Radiol. 22(4):431-6, 2011
                                              5. Stecker MS et al: Guidelines for patient radiation dose management. J Vasc Interv Radiol. 20(7 Suppl):S263-73, 2009