Ions have charge– Cations +– Anions -

Isotopes vary in mass– Neutrons– Radioisotopes

Unstable nuclei Emit energy -radiation Medical uses as tracers and treating disease

Ions and IsotopesIons and Isotopes

Alpha Particles: 2 neutrons and 2 protonsThey travel short distances, have large massOnly a hazard when inhaled

Four Primary Types of Four Primary Types of Ionizing Radiation:Ionizing Radiation:

Alpha ParticlesAlpha Particles

Four Primary Types of Four Primary Types of Ionizing Radiation:Ionizing Radiation:

Beta ParticlesBeta ParticlesBeta Particles: Electrons or positrons having small mass and variable energy. Electrons form when a neutron transforms into a proton and an electron or when a proton transforms into a positron and a neutron:

Four Primary Types of Four Primary Types of Ionizing Radiation:Ionizing Radiation:

Gamma RaysGamma Rays

Gamma Rays (or photons): Result when the nucleus releases

Energy, usually after an alpha, beta or positron transition

Four Primary Types of Four Primary Types of Ionizing Radiation:Ionizing Radiation:

X-RaysX-Rays

X-Rays: Occur whenever an inner shell orbital electron is removed

and rearrangement of the atomic electrons results with the release of

the elements characteristic X-Ray energy

Four Primary Types of Four Primary Types of Ionizing Radiation:Ionizing Radiation:

NeutronsNeutrons

Neutrons: Have the same mass as protons but are uncharged

They behave like bowling balls

Four Primary Types of Four Primary Types of Ionizing RadiationIonizing Radiation

Alpha particlesBeta particlesGamma rays (or photons)X-Rays (or photons)Neutrons

Ionization Ionization Ionization Ionization

Ionizing radiation is produced by unstable atoms. Unstable atoms differ from stable atoms because they have an excess of energy or mass or both.

Unstable atoms are said to be radioactive. In order to reach stability, these atoms give off, or emit, the excess energy or mass. These emissions are called radiation.

Ionizing radiation is produced by unstable atoms. Unstable atoms differ from stable atoms because they have an excess of energy or mass or both.

Unstable atoms are said to be radioactive. In order to reach stability, these atoms give off, or emit, the excess energy or mass. These emissions are called radiation.

Types or Products of Ionizing Types or Products of Ionizing RadiationRadiation

Types or Products of Ionizing Types or Products of Ionizing RadiationRadiation

or X-

rayneutron

DNA and RadiationDNA and Radiation

Ionizing Radiation at the Ionizing Radiation at the Cellular LevelCellular Level

Causes breaks in one or both DNA strands or;

Causes Free Radical formation

Commonly Transported Commonly Transported RadioisotopesRadioisotopes

Americium-241= Diagnose thyroid disorders, smoke detectors.

Cesium-137= Cancer treatment.Iodine-125,131= Diagnosis & treatment

liver, kidney,heart, lung and brain.Technetium-99m=Bone and brain imaging;

thyroid and liver studies; localization of brain tumors.

Americium-241= Diagnose thyroid disorders, smoke detectors.

Cesium-137= Cancer treatment.Iodine-125,131= Diagnosis & treatment

liver, kidney,heart, lung and brain.Technetium-99m=Bone and brain imaging;

thyroid and liver studies; localization of brain tumors.

radrad

1 rad = 1 Roentgen

remrem

The unit of dose equivalent for any type of ionizing radiation absorbed by body tissue in terms of estimated biological effect - Unit of dose equivalent

Dose in health record is in units of rem1 rem = 1 Roentgen1 Sievert (Sv) = 100 REM1 mSv = 100 mREM

Roentgen Equivalent Man

Quality Factor (Q)Quality Factor (Q)

The specific value that accounts for the ability of different types of ionizing radiation to cause varying degrees of biological damage– X-rays, gamma rays, & beta particles 1– Neutrons & High energy protons 10– Alpha Particles 20

Units of RadioactivityUnits of Radioactivity

Curie (Ci) = 2.22 E12 dpm or 3.7E10 dpsBecquerel (Bq) = 1 dpsMaximum Dose/year = 5 REM or 50 mSvMaximum Dose/year for Declared Pregnant

Woman & Minors= 0.5 REM or 5 mSv

          

Half Life CalculationHalf Life Calculation

Annual Dose LimitsAnnual Dose LimitsExternal/Internal Exposure Limits for Occupationally Exposed Individuals

  Adult ($18 yrs) Minor (< 18 yrs)

Whole body* 5000 mrem/yr 500 mrem/yr

Lens of eye 15000 mrem/yr 1500 mrem/yr

Extremities 50000 mrem/yr 5000 mrem/yr

Skin 50000 mrem/yr 5000 mrem/yr

Organ 50000 mrem/yr 5000 mrem/yr

*Effective dose equivalent

Dose Response RelationshipsDose Response Relationships

0-150 rem—No or minimal symptoms150-400 rem—Moderate to severe illness400-800 rem—Severe illness deaths start

above 500 remAbove 800 rem—Fatal

***Acute whole body doses

Your Annual ExposureYour Annual ExposureActivity Typical Dose

Smoking 280 millirem/year

Radioactive materials use  in a UM lab

<10 millirem/year

Dental x-ray 10 millirem per x-ray

Chest x-ray  8 millirem per x-ray

Drinking water  5 millirem/year

Cross country round trip by air  5 millirem per trip 

Coal Burning power plant 0.165 millirem/year 

Subjects Total subjects (n)

Subjects undergoing more than 1 procedure (%)

Mean annual effective dose from procedures (mSv)

All subjects 952 420 68.8 2.4

•Males 453 078 57.9 2.3

•Females 499 342 78.7 2.6

•18–34 y 233 586 49.5 1.0

•35–39 y 118 365 65.7 1.6

•40–44 y 144 728 72.1 2.0

•45–49 y 146 703 74.9 2.6

•50–54 y 131 209 78.2 3.3

•55–59 y 115 520 79.5 4.1

•60–64 y 62 309 85.9 5.2

Effective doses of ionizing radiation from medical Effective doses of ionizing radiation from medical proceduresprocedures

Fazel R et al. N Engl J Med 2009; 361: 849-57.

Procedure Average effective dose (mSv)

Proportion of the total effective dose from all study procedures (%)

Myocardial perfusion imaging 15.6 22.1CT of abdomen 8 18.3CT of pelvis 6 12.2CT of chest 7 7.5Diagnostic cardiac catheterization 7 4.6Radiography of the lumbar spine 1.5 3.3Mammography 0.4 3.1CT angiography of the chest (noncoronary)

15 3.1

Upper gastrointestinal series 6 2.4CT of head or brain 2 2.0PCI 15 1.8

Medical imaging procedures with largest Medical imaging procedures with largest contribution to cumulative effective dosecontribution to cumulative effective dose

Fazel R et al. N Engl J Med 2009; 361: 849-57.

Estimated Exposure To The Estimated Exposure To The National PopulationNational Population

Between 320 – 360 mr/yrBetween 320 – 360 mr/yr