1. Chapter1 & 9 History of Radiology and X-ray Tube

2. Timeline of Radiology
1895- Roentgen’s discoveries X-ray or Roentgen rays Thomas Edison developed the first fluoroscope first reported case of biological damage 1921 Potter-Bucky grid was introduced

3. Timeline 1942 first AEC was demonstrated
1942 first automatic processor developed
calcium tungstate screen cassettes
1970 Intensifying screens
1979 First digital

4. Timeline
1982 PACS Picture Archiving & Communications Systems ( storage & access of digital images)
1982 Teleradiolgy
1980s CR Computed Radiography (cassette converting images to electronic signal and stored in a computer (filmless)

5. Timeline
1996 DR direct digital image is directly captured by electronic elements with no intermediate step ( cassettesless)

6. Important facts Natural Radiation
¾ of all radiation we receive comes from nature rather than technology
Minerals in ground ( Terrestrial)
Cosmic
Internal
Radon

7. Manmade Radiation/Other
Medical x-rays
Nuclear medicine
Consumer products
Fallout
Occupational

8. ALARA As Low As Reasonably Achievable
X-ray profession is a safe profession

9. Background of Radiology
Discovery of x-ray- November 8, 1895 by Wilhelm Conrad Roentgen in Germany

10. First x-ray
Roentgen’s wife's hand

11. X-ray Tubes
Crooke’s Tube
Jackson Focus Tube
Coolidge Hot Cathode

12. Modern x-ray tube

13. Modern x-ray tube Cathode- negative electrode, source of electrons
Consists of the following:
Highly evacuated glass tube
Two sealed electrodes, Cathode and Anode
Cathode- negative electrode, source of electrons
Anode - positive electrode, source of radiation (x-rays)

14. Cathode negatively charged
Contains a spiral, incandescent filament of tungsten wire
Filament is heated by an electrical current of low amperage from a transformer
Temperature of the filament, controlled by the amount of current passing through it, controls the number of electrons emitted

15. Cathode Filament Source of electrons Coiled tungsten wire Focusing cup
Filament current
Thermionic emission
Coiled tungsten wire
Large and small
Focusing cup
Space charge effect

16. Thermionic Electron Emission
Another reason for the high melting point of tungsten is that the filament gets so hot it actually glows. This glowing is called incandescence. And the process is known as thermionic emission.
When the filaments gets that hot it the electrons are “boiled off” or freed from the atoms.

17. Current
Higher the temperature of the filament, the more electrons emitted
Direct relationship
Stream of electrons from cathode to anode is known as the tube current
Current is measured in milliamperes (mA)
Stream of electrons are taken from cathode to anode by a transformer (kVp)
The speed with which the electrons cross the gap between the cathode and the anode.

18. Anode
Two types
Stationary- could be melted from the intense bombardment of electrons.
Rotating- composed of metal with a good heat conducting characteristics (molybdenum)
Disc shaped anode is coated with an alloy made of tungsten and rhenium

19. Anode Rotating anode Target Requires a stator and rotor to rotate
Tungsten metal
High melting point
Efficient x-ray production
Target
Decelerates and stops electrons
Energy converted to heat and x-rays
Bremsstrahlung and characteristic interactions

20. Producing X-rays Voltage kicks in, takes electrons across the tube
Thermionic Emission is a boiling off effect, electrons move by heat raising the temperature and the electrons boil off the filament
Voltage is then responsible for taking the electrons across the tube to the anode (kVp)

21. Producing X-rays
Anode is made of tungsten and rhenium because they have high melting points
Anode needs to slow down or stop the electrons
Once electrons reach the anode they become photons
Each photon accounts for one x-ray

22. Review Who invented x-rays? What year were x-rays invented?
What was the name of the first tube used when x-rays were invented?
What was the problem with the first x-ray tube?
What was the problem with the second x-ray tube?

23. What are x-rays?
X-ray production is the striking of matter by high speed electrons.
X-rays are generated in x-ray tube
form of electromagnetic radiation
Form of invisible radiant energy
Have short wavelengths; gives x-rays ability to penetrate materials that would normally reflect or absorb light

24. Behaviors of x-rays Two behaviors: Waves and Particles
Have shorter wavelengths than regular light
Consist of small bundles of energy called photons
Wavelength vs. kVp
as kVp is increased, the wavelength of x-rays decreases; indirect relationship

25. X-rays as Energy A form of electromagnetic radiation
Behave both like waves and like particles
Move in waves that have wavelength and frequency
Wavelength and frequency are inversely related
X-rays also behave like particles and move as photons

26. Properties of x-rays
Can penetrate materials that normally absorb or reflect light due to short wavelengths
Cause certain objects to fluoresce- ability to emit natural light.
Ability to penetrate solid and opaque materials to produce an image
X-rays are invisible

27. Properties of x-rays
Can produce biological changes that can stimulate or retard growth
X-rays travel in straight lines
Travel at the speed of light ( 186,000 miles per second)
Ionize gases by removing electrons from atoms to form ions ( negatively charged atoms)

28. Features of X-ray Tube
All x-ray tubes are a vacuums, free of air, air impedes the flow of electrons
X-rays are produced when energy is changed from one ion to another
Cathode is negatively charged source of electrons
Anode positively charged source of electrons

29. Features of X-ray Tube
Anode spins & 10,000 revolutions per minute
Spinning the anode, prevents the same spot on the anode from being hit by the stream of electrons
Exposure switch- two functions: rotor and exposure
Rotor- activates the anode to begin spinning

30. Features of X-ray Tube
Rotor also activates the electrons on the cathode to begin to group and form on the tungsten filament
Exposure switch- releases the electrons to be propelled from the cathode to the target of the anode and x-rays are produced

31. mAs and kVp
mAs (milliampere quantity) controls the amount of radiation that will be produced.
mAs supplies the current to the cathode
kVp (kilovoltage peak)(quality) is the voltage, penetrating ability, power, strength of the electrons traveling across the cathode to the anode.

32. X-ray Production
The production of x-rays requires a rapidly moving stream of electrons that are suddenly decelerated or stopped.
The negative electrode (cathode) is heated, and electrons are emitted (thermionic emission).
The electrons are attracted to the anode, move rapidly towards the positive electrode, and are stopped or decelerated.