Week 1 :Concepts of Radiologic Science RTEC 111 1

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 2

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

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

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 5

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. 6

kilo  Kilo stands for 1000  Kilogram = 1000 grams 7

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Building blocks of matter  Atom  Molecules  Elements  Compounds 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

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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. 21

Exposed or Irradiated  Matter that intercepts radiation and absorbs part or all of it is exposed or irradiated 22

Is all radiation harmful? 23

X-rays  You will learn to expose or irradiate patients for medical treatments or diagnosis 24

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. 25

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. 26

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. 27

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What is Ionization? 29

Examples of Ionizing Radiation  X-rays, gamma rays, and ultraviolet light 30

Ionization  Some particles with high kinetic energy can cause ionization  Ex: Alpha & Beta particles 31

Sources of Ionizing Radiation Natural Environmental Radiation Man – made Radiation 32

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. 33

MEDICAL IMAGING Diagnostic Imaging –Medical xrays –Dental xrays GREATEST SOURCE OF MAN- MADE RADIATION 34

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 35

What does this information mean? How does this affect us? 36

Is this a safe profession ? Natural radiation = 300 mrem/yr Average medical exposure = 50 mrem/yr 39 – 320 mrem/yr Technologists? 37

How Medical X-Ray Began 38

Crookes Tubes  Were the beginning of the modern fluorescent lamps and x-ray tubes. 39

Historical Perspectives 40

Collaborative Events 41

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First Radiograph 45

“Willie Rontgen”  Honored in 1901 with the first Nobel prize in physics for his efforts. 46

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 47

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. 48

X-Ray Properties  Travel in straight lines.  Travel at the speed of light, 3 X 10 8 meters per second in a vacuum or 299,792,458 m/s. or 29,979,245,800 cm/s  Can ionize matter. 49

X-Ray Properties  Cause fluorescence of certain crystals.  Cannot be focused by a lens.  Affects photographic film. 50

X-Ray Properties  Produce chemical and biological changes in matter through ionization and excitation.  Produce secondary and scatter radiation. 51

Later years Radiologist experienced much higher rates of blood disorders than in others Began the study of RADIATION PROTECTION 52

Where is the RADIATION PROTECTION? 53

Early years in Radiologic Technology Nurses or nurses aides taught how to “take an x-ray” NO special education Only “ON THE JOB” training Experience the best teacher The first Technologist is credited to be EDWARD C. JERMAN. 54

In 30 years Developed from a technical trade to one of a professionalism Once thought that anyone could be trained to quickly = “push the buttons’ To now where it is considered a profession that requires analytical thinking and problem solving 55

Questions ? 56