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RAD 315 RADIATION BIOLOGY AND PROTECTION

RAD 315 RADIATION BIOLOGY AND PROTECTION. INTRODUCTION. Radiation Protection. The promotion of practices that limit exposure to ionizing radiation to a minimum. Applies radiation physics and radiation biology in a clinical setting. Goal of Radiation Protection.

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RAD 315 RADIATION BIOLOGY AND PROTECTION

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  1. RAD 315 RADIATION BIOLOGY AND PROTECTION INTRODUCTION

  2. Radiation Protection • The promotion of practices that limit exposure to ionizing radiation to a minimum. • Applies radiation physics and radiation biology in a clinical setting

  3. Goal of Radiation Protection • Maximize the benefit of an examination or procedure while minimizing the risk to the patient. • ALARA- “as low as reasonably achievable” • It is assumed that radiation causes harm and any exposure should be kept to a minimum.

  4. Radiation Biology • Branch of science that looks at the effects of ionizing radiation on living matter. • Most effects are on cellular level

  5. Radiation Units

  6. Radiation Units • To express radiation units there are two types of measurement • Traditional- typically used in the United States • SI- Systeme International- universally used around the world

  7. EXPOSURE IN AIR • SI Unit- coulombs per kilogram (C/kg) • Traditional- Roentgen (R) • Measures the ionization of air produced by x-radiation and gamma radiation below 3 million electron volts (3 MeV)

  8. Coulombs / kg • SI expression of exposure in air • The coulomb is the SI unit of electric charge and represents a given number of electrons. • The kilogram measures the quantity of air • Hence the amount of electric charge in a quantity of air.

  9. Roentgen • Named after Wilhelm Conrad Roentgen (discovered x-rays) • Measure of the amount of ionization produced by x-radiation or gamma radiation in air.

  10. ABSORBED DOSE • SI Unit- Gray (Gy) • Traditional- rad (radiation absorbed dose)

  11. Gray and rad 1 rad= 1cGy =1/100 Gray = 0.01 Gy • Rad- an energy transfer of 100 ergs (energy unit) per gram of absorbing material • Patient dose is usually expressed Gray.

  12. Occupational Exposure • SI Unit- Sievert • Traditional- rem (radiation equivalent man) Units of biological effect

  13. Rems and Sieverts • Rems – the quantity of ionizing radiation that has the same biologic effect of 1 rad of x-ray. • 1 rad= 1 rem • 1 Sievert = 100 rem

  14. RADIOACTIVITY • SI Unit- Becquerel- Bq • Traditional- Curie- Ci • Measures the rate of radioactive decay of a material.

  15. Curies & Becquerels • Curie- 3.7x1010 disinergrations per second of any radioactive substances. • Becquerels- one decay per second of any radioactive substance • The curie is a larger unit that the becquerel.

  16. Half Life • The time it takes a radioactive material to decay 50% of its original activity is known as the HALF LIFE. • Ex: If you had 100 atoms of radioactive material and it takes 3 hours for 50 of them to decay. What is the half life of this material?

  17. CONVERSIONS • 1 Gy=_______mrads • 1 Gy= 100 rad= 100,000 mrads • 100 rem= 1 Sievert

  18. Think About It! • The prescription says that the patient is to receive 1.8 Gy of radiation. How many cGy of radiation will the patient receive? • Which is a larger? • Becquerel or curie? • 10,000 mrems or 1 Sievert • 1 Gray or 1000 rads

  19. THE END Any Questions?

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