Reducing Radiation in Interventional Imaging

By the end of this course you will be able to: Identify different types of ionizing radiation Review basic radiation safety principles Explain short-term effects of radiation Explain long-term effects of radiation Describe features available to reduce dose to patient and operator (CARE) Combined Applications to Reduce Exposure Embolizations PT(C)A Stent Placements Ablations: EP or Liver PTC TIPS Thrombolysis ERCP TAVI VSD Occlusion   Radiation: Transfer energy in space and medium X-ray Production: Collision of electrons- with nucleus+ Atom: Electron, Proton, & Neutron Nucleus = Proton (+) & Neutron Orbit/Shell = Electron (-) Bremsstrahlung Characteristic Factor Patient Staff kVP Increased Dose   mA Increased Dose Increased Dose Time Increased Dose Increased Dose Filter Decreased Dose   Collimation Decreased Dose Decreased Dose SID Increased Dose Increased Dose FOV Increased Dose Increased Dose C-arm Angle Increased Dose Increased Dose Patient Size Increased Dose Increased Dose Quantity SI unit and symbol Non-SI unit Conversion factor Radioactivity becquerel, Bq curie, Ci 1 Ci = 3.7 x 1010 Bq = 37 Gigabecquerels (GBq) 1 Bq = 27 picocurie (pCi) Radiation Absorbed dose gray, Gy rad 1 rad = 0.01 Gy "Dose" (Equivalent dose) sievert, Sv rem 1 rem = 0.01 Sv 1 rem = 10 mSv Procedure *Approximate effective dose Comparable to natural background radiation for **Additional lifetime risk of fatal cancer from examination ABDOMINAL REGION: Computed Tomography (CT) - Abdomen and Pelvis 15 msV 5 years Low Computed Tomography (CT) - Abdomen and Pelvis, repeated with and without contrast material 30 mSv 10 years Moderate Computed Tomography (CT) - Colonography 10 mSv 3 years Low Radiography (X-ray) - Lower GI Tract 8 mSv 3 years Low Radiography (X-ray) - Upper GI Tract 6 mSv 2 years Low BONE: Radiography (X-ray) - Spine 1.5 mSv 6 months Very Low Radiography (X-ray) - Extremity 0.001 mSv 3 hours Negligible CENTRAL NERVOUS SYSTEM: Computed Tomography (CT) - Head 2 mSv 8 months Very Low Computed Tomography (CT) - Head, repeated with and without contrast material 5 mSv 16 months Low Computed Tomography (CT) - Spine 6 mSv 2 years Low CHEST: Computed Tomography (CT) - Chest 7 mSv 2 years Low Computed Tomography (CT) - Chest Low Dose 1.5 mSv 6 months Very Low Radiography (X-ray) - Chest 0.1 mSv 10 days Minimal HEART: Coronoary Computed Tomography Angiography (CTA) 16 mSv 5 years Low Cardiac CT for Calcium Scoring 3 mSv 1 year Low BONE DENSITOMETRY: Bone Densitometry (DEXA) 0.001 mSv 3 hours Negligible MAMMOGRAPHY: Mammography 0.4 mSv 7 weeks Very Low **LEGEND Risk Level Approximate additional risk of fatal cancer for an adult from examination Negligible less than 1 in 1,000,000 Minimal 1 in 1,000,000 to 1 in 100,000 Very Low 1 in 100,000 to 1 in 10,000 Low 1 in 10,000 to 1 in 1,000 Moderate 1 in 1,000 to 1 in 500 Note: These risk levels represent very small additions to the 1 in 5 chance we all have of dying from cancer *The effective doses are typical values for an average-sized adult.  The actual dose can vary substantially, depending on a person's size as well as on differences in imaging practices   Radiation may pass through the cell without causing any damage Radiation may damage the cell but it is able to repair itself and function normally Radiation may damage the cell so it not only fails to repair itself, but reproduces in the damaged form: Biological Response The radiation causes so much cellular damage, the cell dies Two groups: genetic and carciongenic effects As dose increases, probability for cancer or genetic mutation increases No threshold dose for adverse effects Dose threshold exists for induced damage As dose increases, severity of damage increases May result from high dose to part or entire body Balter S et. al., Radiology 2010; 254:326-341 Measurement chamber integrated into the collimator housing DAP and skin dose displayed During fluoro: skin dose During fluoro pause: accumulated skin dose Effective skin dose control Three thresholds defined When a threshold is exceeded A skin dose indicator on the live display flashes A warning popup is displayed on the ECC Archive dose information in DICOM format Number of exposures, total fluoro time, dose area product Enhanced in-house dose reporting to prepare for future legal requirements You should now be able to: Identify different types of ionizing radiation Review basic radiation safety principles Explain short-term effects of radiation Explain long-term effects of radiation Describe features available to reduce dose to patient and operator (CARE)