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Week 1 :Concepts of Radiologic Science
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  1. Week 1 :Concepts of Radiologic Science RTEC 111

  2. Welcome to the field of medical imaging • Objectives: • Matter, energy, the electromagnetic spectrum – ionizing radiation • Relative intensity of ionizing radiation • Discovery of x-radiation • Basic concepts of radiation protection

  3. Matter and Energy • Matter = anything that has mass and occupies space. • Energy = the ability to do work

  4. Matter • A primary characteristic of matter is “mass”. • Mass = the quantity of matter contained in any physical object.

  5. Mass vs Weight • For our purposes mass and weight can be considered the same. • In the strictest sense they are not the same. • Mass = energy equivalence • Weight = the force exerted on a body under the influence of gravity

  6. Mass • Mass is measured in kilograms (kg). • How many grams are in a kilogram? • Kilogram is the scientific unit of mass and is unrelated to gravitational effects.

  7. kilo • Kilo stands for 1000 • Kilogram = 1000 grams

  8. Atom Molecules Elements Compounds Building blocks of matter

  9. Energy • Define Energy? • Energy can exist in several forms • Energy can be measured in varied units of measurement. The International System (SI) = joules (J). In Radiology = electron volt (eV) (ex: e- energy vs. kVp)

  10. Several forms of Energy

  11. Potential energy • Ability to do work by virtue of position. • Ex: roller coaster or stretch spring.

  12. Kinetic energy • Energy of Motion • Work because of motion • Ex: moving car, moving river

  13. Chemical energy • Energy released by chemical reaction • Ex: energy from the food we eat.

  14. Electrical energy • Electrons moving through an electrical potential difference • Ex: household electricity – 110 volts

  15. Thermal energy (heat) • Energy of motion at the atomic and molecular level. The kinetic energy of molecules vibrating • Ex: Heat from an X-ray tube

  16. Nuclear energy • Energy contained in the nucleus of an atom • Ex: nuclear electric power plants

  17. Electromagnetic energy • Not as familiar to us as other forms of energy … but very important to radiographers • Results from electric and magnetic disturbances in space • This energy is produced by the acceleration of a charge

  18. Radio waves, microwaves, ultraviolet, infrared, visible light… what else?

  19. Electromagnetic energy • Is often referred to Electromagnetic radiation when it is traveling through space. • Radiation is the transfer of energy (usually through space) • When a guitar string vibrates it is said to radiate sound.

  20. Exposed or Irradiated • Matter that intercepts radiation and absorbs part or all of it is exposed or irradiated

  21. Is all radiation harmful?

  22. X-rays • You will learn to expose or irradiate patients for medical treatments or diagnosis

  23. X-Rays are Ionizing radiation X-rays are a special type of radiation. X-rays are capable of removing an orbital electron from the atom with which it interacts.

  24. Ionization • Ionization occurs when an x-ray passes close to an orbital electron of an atom and transfers sufficient energy to the electron to remove it from the atom.

  25. Ion pair • The orbital electron and the atom from which it was separated are called an ion pair. • The electron is a negative ion and the atom is a positive ion.

  26. What is Ionization?

  27. Examples of Ionizing Radiation • X-rays, gamma rays, and ultraviolet light

  28. Ionization • Some particles with high kinetic energy can cause ionization • Ex: Alpha & Beta particles

  29. Sources of Ionizing Radiation • Natural Environmental Radiation • Man – made Radiation

  30. Natural radiation • Natural radiation accounts for approximately 300 millirem (mrem) • 3 sources of environmental radiation: cosmic rays, terrestrial radiation and internally deposited radionuclides. The largest source of natural radiation is radon.

  31. MEDICAL IMAGING • Diagnostic Imaging • Medical xrays • Dental xrays • GREATEST SOURCE OF MAN-MADE RADIATION

  32. Diagnostic x-rays • 1990 the National Council on Radiation Protection and Measurements (NCRP) • 39 mrem/yr OR 0.39 mSv/yr • More recent NCRP estimates indicate nearly 320 mrem/yr OR 3.2 mSv/yr. Due to increasing use of multslice spiral CT and high-level fluoroscopy

  33. What does this information mean?How does this affect us?

  34. Is this a safe profession ? • Natural radiation = 300 mrem/yr • Average medical exposure = 50 mrem/yr 39 – 320 mrem/yr • Technologists?

  35. How Medical X-Ray Began

  36. Crookes Tubes • Were the beginning of the modern fluorescent lamps and x-ray tubes.

  37. Historical Perspectives

  38. Collaborative Events

  39. First Radiograph

  40. “Willie Rontgen” • Honored in 1901 with the first Nobel prize in physics for his efforts.

  41. X-Ray Properties: Roentgen’s discovery • Are highly penetrating, invisible rays which are a form of electromagnetic radiation. • Are electrically neutral and therefore not affected by either electric or magnetic fields

  42. X-Ray Properties • Can be produced over a wide variety of energies and wavelengths (polyenergetic & heterogeneous). • Release very small amounts of heat upon passing through matter.

  43. X-Ray Properties • Travel in straight lines. • Travel at the speed of light, 3 X 108 meters per second in a vacuum or 299,792,458 m/s. or 29,979,245,800 cm/s • Can ionize matter.

  44. X-Ray Properties • Cause fluorescence of certain crystals. • Cannot be focused by a lens. • Affects photographic film.