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Radiation Safety
Chad Davis, MD; Colin J. McCarthy, MB, BCh, BAO, MRCSI, FFR (RCSI); 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), 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            • Radiation-absorbed dose (rad); outdated unit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), SI unit
            • 1 Sv = 1 joule/kg
            • Sv and Gy are not interchangeable
            • 1 Sv = 100 roentgen equivalent man (rem), 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
                • 5,000 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)
              • Generally, direct result of cell killing
            • Stochastic
              • Probabilistic; nondeterministic health effects
              • Probability of event increases linearly with increasing dose without threshold, but severity of effect is constant (e.g., cancer)
                • Radiation dose only affects probability of stochastic effect occurring
              • Recent research has sought to examine potential role for head and neck cancers in physicians using radiation to perform procedures
              • Due to typical room setup, brain is relatively unprotected, and left side of head is known to be more exposed to radiation than right
              • Disproportionate reports of left-sided brain tumors suggest possibility of causal relation to occupational radiation exposure
            • 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
          • Principles of justification, optimization, and limitation
            • Justification: Proposed radiation exposure should do more good than harm; that is, it should yield individual or societal benefit that is > detriment it causes
            • Optimization: Keeping radiation exposure ALARA, taking into account economic and societal factors
            • Limitation: Total dose to any individual from all regulated sources should not exceed appropriate regulatory limits
          • Cataracts
            • Prior to 2011, threshold for radiation-induced cataract was taken to be 2 Gy (acute) or 5 Gy (chronic)
            • Since 2011, ICRP considers 0.5 Gy to be threshold (acute and chronic) (ICRP Publication 118)

        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. Elsholtz FHJ et al: Radiation exposure of radiologists during different types of CT-guided interventions: an evaluation using dosimeters placed above and under lead protection. Acta Radiol. 284185119852734, 2019
                        2. Mayr NP et al: Assessing the level of radiation experienced by anesthesiologists during transfemoral transcatheter aortic valve implantation and protection by a lead cap. PLoS One. 14(1):e0210872, 2019
                        3. Braun E et al: Reducing Radiation exposure in lumbar transforaminal epidural steroid injections with pulsed fluoroscopy: a randomized, double-blind, controlled clinical trial. Pain Physician. 21(1):53-60, 2018
                        4. Cheon BK et al: Radiation safety: a focus on lead aprons and thyroid shields in interventional pain management. Korean J Pain. 31(4):244-52, 2018
                        5. Kelly R et al: Ionizing radiation dose exposure to the ocular region of pain physicians during C-arm guided pain interventions. Pain Physician. 21(5):E523-32, 2018
                        6. United States Nuclear Regulatory Commission: NRC regulations (10 CFR) part 20: standards for protection against radiation. http://www.nrc.gov/reading-rm/doc-collections/cfr/part020. Published June 31, 2015. Reviewed July 29, 2019. Accessed July 29, 2019
                        7. Roguin A et al: Brain and neck tumors among physicians performing interventional procedures. Am J Cardiol. 111(9):1368-72, 2013
                        8. 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
                        9. Bushberg JT: The Essential Physics of Medical Imaging. Philadelphia: Lippincott Williams & Wilkins, 2012
                        10. Smith JC et al: Ultra-low-dose protocol for CT-guided lung biopsies. J Vasc Interv Radiol. 22(4):431-6, 2011
                        11. Stecker MS et al: Guidelines for patient radiation dose management. J Vasc Interv Radiol. 20(7 Suppl):S263-73, 2009
                        Related Anatomy
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                        Related Differential Diagnoses
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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), 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), SI unit
                                  • 1 Sv = 1 joule/kg
                                  • Sv and Gy are not interchangeable
                                  • 1 Sv = 100 roentgen equivalent man (rem), 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
                                      • 5,000 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)
                                    • Generally, direct result of cell killing
                                  • Stochastic
                                    • Probabilistic; nondeterministic health effects
                                    • Probability of event increases linearly with increasing dose without threshold, but severity of effect is constant (e.g., cancer)
                                      • Radiation dose only affects probability of stochastic effect occurring
                                    • Recent research has sought to examine potential role for head and neck cancers in physicians using radiation to perform procedures
                                    • Due to typical room setup, brain is relatively unprotected, and left side of head is known to be more exposed to radiation than right
                                    • Disproportionate reports of left-sided brain tumors suggest possibility of causal relation to occupational radiation exposure
                                  • 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
                                • Principles of justification, optimization, and limitation
                                  • Justification: Proposed radiation exposure should do more good than harm; that is, it should yield individual or societal benefit that is > detriment it causes
                                  • Optimization: Keeping radiation exposure ALARA, taking into account economic and societal factors
                                  • Limitation: Total dose to any individual from all regulated sources should not exceed appropriate regulatory limits
                                • Cataracts
                                  • Prior to 2011, threshold for radiation-induced cataract was taken to be 2 Gy (acute) or 5 Gy (chronic)
                                  • Since 2011, ICRP considers 0.5 Gy to be threshold (acute and chronic) (ICRP Publication 118)

                              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. Elsholtz FHJ et al: Radiation exposure of radiologists during different types of CT-guided interventions: an evaluation using dosimeters placed above and under lead protection. Acta Radiol. 284185119852734, 2019
                                              2. Mayr NP et al: Assessing the level of radiation experienced by anesthesiologists during transfemoral transcatheter aortic valve implantation and protection by a lead cap. PLoS One. 14(1):e0210872, 2019
                                              3. Braun E et al: Reducing Radiation exposure in lumbar transforaminal epidural steroid injections with pulsed fluoroscopy: a randomized, double-blind, controlled clinical trial. Pain Physician. 21(1):53-60, 2018
                                              4. Cheon BK et al: Radiation safety: a focus on lead aprons and thyroid shields in interventional pain management. Korean J Pain. 31(4):244-52, 2018
                                              5. Kelly R et al: Ionizing radiation dose exposure to the ocular region of pain physicians during C-arm guided pain interventions. Pain Physician. 21(5):E523-32, 2018
                                              6. United States Nuclear Regulatory Commission: NRC regulations (10 CFR) part 20: standards for protection against radiation. http://www.nrc.gov/reading-rm/doc-collections/cfr/part020. Published June 31, 2015. Reviewed July 29, 2019. Accessed July 29, 2019
                                              7. Roguin A et al: Brain and neck tumors among physicians performing interventional procedures. Am J Cardiol. 111(9):1368-72, 2013
                                              8. 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
                                              9. Bushberg JT: The Essential Physics of Medical Imaging. Philadelphia: Lippincott Williams & Wilkins, 2012
                                              10. Smith JC et al: Ultra-low-dose protocol for CT-guided lung biopsies. J Vasc Interv Radiol. 22(4):431-6, 2011
                                              11. Stecker MS et al: Guidelines for patient radiation dose management. J Vasc Interv Radiol. 20(7 Suppl):S263-73, 2009