Principles of Nuclear Cardiology Thomas H. Hauser MD, MMSc, MPH, FACC Director of Nuclear Cardiology Beth Israel Deaconess Medical Center Assistant Professor of Medicine Harvard Medical School Boston, MA A major teaching hospital of Harvard Medical School

Harvard Medical School THH 9/2008 Lecture Schedule 9/8/2008Introduction, Basic PhysicsThomas Hauser, BIDMC 9/15/2008Image ReconstructionTony Parker, BIDMC 9/22/2008Tracers and ProtocolsThomas Hauser, BIDMC 9/29/2008CAD Diagnosis and PrognosisSharmila Dorbala, BWH 10/6/2008Assessment of Myocardial ViabilityMarcelo Di Carli, BWH 10/13/2008Columbus DayNo Lecture 10/20/2008Attenuation ArtifactsThomas Hauser, BIDMC 10/27/2008Technical Aspects of Cardiac CTSuhny Abbara, MGH 11/3/2008Clinical Application of Cardiac CTThomas Hauser, BIDMC 11/10/2008AHANo Lecture 11/17/2008Evaluation of Chest Pain with Cardiac CTUdo Hoffmann, MGH 11/24/2008Coronary Artery PlaqueMel Clouse, BIDMC 12/1/2008RSNANo Lecture 12/8/2008PET/CTMarcelo Di Carli, BWH 12/15/2008"Triple Rule Out" CTVassilios Raptopoulos, BIDMC 12/22/2008Radiation Dosimetry and SafetyThomas Hauser, BIDMC

Harvard Medical School THH 9/2008 Advances in Nuclear Cardiology

Harvard Medical School THH 9/2008 Advances in Nuclear Cardiology Hachamovich et al, Circulation 2002;105:823-9

Harvard Medical School THH 9/2008 Our Goal Image the heart

Harvard Medical School THH 9/2008 Our Tools Tracers Camera

Harvard Medical School THH 9/2008 Outline Tracers - Nuclear Physics –Atomic structure –Radioactive decay –Specific radionuclides Camera - Gamma Camera –Collimators –Energy selection Radiation Safety

Harvard Medical School THH 9/2008 Outline Tracers - Nuclear Physics –Atomic structure –Radioactive decay –Specific radionuclides Camera - Gamma Camera –Collimators –Energy Selection Radiation Safety

Harvard Medical School THH 9/2008 Atom

Harvard Medical School THH 9/2008 Nucleus Proton –Charge +1 –Mass amu = 938 MeV Neutron –No charge –Mass amu = 939 MeV

Harvard Medical School THH 9/2008 E = m 0 c 2 Energy can be converted to mass and vice versa

Harvard Medical School THH 9/2008 Notation Element Symbol Atomic Weight {Atomic Number} Oxygen = 16 O = 15 O Carbon = 12 C = 13 C = 11 C

Harvard Medical School THH 9/2008 Definitions Nuclide –Specific combination of protons and neutrons ( 12 C) Radionuclide –Nuclide that undergoes radioactive decay ( 11 C) Isotopes –Nuclides that share the same number of protons Same element (identical chemical properties) but different mass

Harvard Medical School THH 9/2008 Stable Nuclei

Harvard Medical School THH 9/2008 Radioactive Decay Radioactive decay is the process by which unstable nuclei move towards the line of stability by emitting particles and/or photons and releasing nuclear energy

Harvard Medical School THH 9/2008 Radioactive Decay Mother nucleus Daughter nucleus Emission Mother Daughter A M  B D + Emission

Harvard Medical School THH 9/2008 Modes of Decay α: Emission of a helium nucleus β-: Emission of an electron β+: Emission of a positron γ: Emission of a photon –Isomeric transition –Competes with internal conversion Electron Capture: Absorption of an electron with emission of photons Fission –Formation of two daughter nuclei

Harvard Medical School THH 9/2008 What is the difference between a γ-ray and an x-ray? There all just photons!

Harvard Medical School THH 9/2008 α Decay

Harvard Medical School THH 9/2008 β- Decay

Harvard Medical School THH 9/2008 β+ Decay

Harvard Medical School THH 9/2008 β+ Annihilation

Harvard Medical School THH 9/2008 β+ Annihilation

Harvard Medical School THH 9/2008 Electron Capture Releases characteristic x-rays Competes with β+ decay

Harvard Medical School THH 9/2008 γ Decay Can occur in conjunction with all other modes of decay Isomeric transition Competes with internal conversion Emission of a conversion electron

Harvard Medical School THH 9/2008 What is the emission that we care about as Nuclear Cardiologists? Photons!

Harvard Medical School THH 9/2008 Radioactive Decay α β- β + EC

Harvard Medical School THH 9/2008 Decay: Half Life

Harvard Medical School THH 9/2008 Transient Equilibrium

Harvard Medical School THH 9/2008 Technetium Generator

Harvard Medical School THH 9/2008 Outline Tracers - Nuclear Physics –Atomic structure –Radioactive decay –Specific radionuclides Camera - Gamma Camera –Collimators –Energy Selection Radiation Safety

Harvard Medical School THH 9/2008 Photons Interact with Matter No interaction Photoelectric absorption Compton scattering {Pair production} {Coherent scattering}

Harvard Medical School THH 9/2008 Photoelectric Absorption

Harvard Medical School THH 9/2008 Compton Scattering

Harvard Medical School THH 9/2008 Attenuation

Harvard Medical School THH 9/2008 Energy Spectrum 137 Cs

Harvard Medical School THH 9/2008 Gamma Camera

Harvard Medical School THH 9/2008 Gamma Camera Goals Absorb photons Coming from directly in front of the camera But not the scattered photons

Harvard Medical School THH 9/2008 Gamma Camera

Harvard Medical School THH 9/2008 Collimator

Harvard Medical School THH 9/2008 Why Use a Collimator

Harvard Medical School THH 9/2008 NaI(Tl) Crystal

Harvard Medical School THH 9/2008 NaI(Tl) Crystal

Harvard Medical School THH 9/2008 The Back End Determines position of absorbed photon Accepts only those photons that were not scattered toward the camera

Harvard Medical School THH 9/2008 Energy Window: Tc-99m 141keV

Harvard Medical School THH 9/2008

Harvard Medical School THH 9/2008 Patient Positioning

Harvard Medical School THH 9/2008 Raw Data

Harvard Medical School THH 9/2008 Outline Tracers - Nuclear Physics –Atomic structure –Radioactive decay –Specific radionuclides Camera - Gamma Camera –Collimators –Energy Selection Radiation Safety

Harvard Medical School THH 9/2008 Radiation Safety Time Distance Shielding

Harvard Medical School THH 9/2008 Radiation Safety Activity: Becquerel (= 2.7* Curie) Absorbed dose: Gray (= 100 rad) Biologically effective dose: Sievert (= 100 rem) Absorbed dose is a function of activity and time Biologically effective dose is the absorbed dose multiplied by a quality factor (for photons, =1)

Harvard Medical School THH 9/2008 Example Radiation Exposures

Harvard Medical School THH 9/2008 You Exposure Increases by 1 mREM from… Three days of living in Atlanta Two days of living in Denver About seven hours in some spots in the Espirito Santo State of Brazil. An average year of TV watching A year of wearing a luminous dial watch A coast-to-coast airline flight

Harvard Medical School THH 9/2008 Time Spend as little time as possible near radiation –Delivered dose is a function of time

Harvard Medical School THH 9/2008 Distance The dose of radiation decreases as the square of the distance between you and the source –Increases as the square of the distance as you get closer

Harvard Medical School THH 9/2008 Shielding If you must spend a significant amount of time near a radiation source, use as much shielding as possible –Lead –Plastic

Harvard Medical School THH 9/2008 Lead Shielding

Harvard Medical School THH 9/2008 Plastic Shielding Best for β emitters –Prevents bremsstrahlung

Harvard Medical School THH 9/2008 Summary Tracers - Nuclear Physics –Atomic structure –Radioactive decay –Specific radionuclides Camera - Gamma Camera –Collimators –Energy Selection Radiation Safety