An early x-ray by Wilhem Rontgen An early x-ray by Wilhem Rontgen Wikipedia. “ X-Ray.” Wikipedia, pgs 1-17. Retrieved from: https://en.wikipedia.org/wiki/X-ray

W W F Wavelength x Frequency = Speed of light W W F Wavelength x Frequency = Speed of light Engineering World Health (2015), Great X-Ray Presentation. Retrieved from library.ewh.org

Electromagnetic Spectrum NASA (2007). Electromagnetic Spectrum [image]. Retrieved from https://commons.wikimedia.org/wiki/File:EM_Spectrum_Properties_edit.svg

Shorter wavelength, higher energy Higher frequency, higher energy ENERGY Ability to penetrate Shorter wavelength, higher energy Higher frequency, higher energy

X-ray Characteristics X-ray Characteristics Travel in straight line Cannot be focused to a point Differentially absorbed Cause fluorescence Harmful to living tissue

X-ray Characteristics X-ray Characteristics High energy waves No mass No charge (neutral) Travel at speed of light Invisible

X-ray Machine Tubehead Support arms Control panel

Strengthening Specialised Clinical Services in the Pacific. User Care of Medical Equipment: A first line maintenance guide for end users. (2015).

X-ray Tube Daniel W. Rickey, Typical Rotating anode X-ray Tube [photograph]. Retrieved from https://en.wikipedia.org/wiki/X-ray_tube#/media/File:Rotating_anode_x-ray_tube_(labeled).jpg

X-ray Tube A- Anode C- Cathode T- Anode Target W- X Ray Window X-ray Tube A- Anode C- Cathode T- Anode Target W- X Ray Window ChumpusRex (2006). Simplified schematic of a x-ray tube in housing [image]. Retrieved from https://commons.wikimedia.org/wiki/File:Xraytubeinhousing_commons.png

Thermionic Emission Release of electrons from hot filament when current flows after depressing exposure switch Deglr6328 (2007), Thermionic filament [photograph]. Retrieved from https://commons.wikimedia.org/wiki/File:Thermionic_filament.jpg The hotter the filament gets, the greater the number of electrons that are released.

Anode Dental x-ray machines have stationary anode side view front view Dental x-ray machines have stationary anode side view front view Target Copper stem Target Engineering World Health (2015), Great X-Ray Presentation. Retrieved from library.ewh.org

Medical Radiography Anode (blue edge is tungsten) Filament/ Anode (blue edge is tungsten) Filament/ Focusing Cup Electron beam strikes target in this area only Engineering World Health (2015), Great X-Ray Presentation. Retrieved from library.ewh.org

Tungsten (Filament and Target) High atomic number (Z=74) (Filament and Target) High atomic number (Z=74) Transfers heat readily High melting point (3422º C) Can be drawn into fine wire

Line Focus Principle The smaller the focal spot (target), the sharper the image (teeth) will be. During x-ray production, a lot of heat is generated. If the target is too small, it will overheat and burn up.

Line Focus Principle PID Target Anode (+) Cathode (-) Target Anode (+) Cathode (-) Apparent (effective) focal spot size Actual focal spot size PID Engineering World Health (2015), Great X-Ray Presentation. Retrieved from library.ewh.org

Line Focus Principle PID Actual focal spot size Actual focal spot size (looking perpendicular to the target surface) Apparent (effective) focal spot size (looking at target surface through PID) PID Engineering World Health (2015), Great X-Ray Presentation. Retrieved from library.ewh.org

X-ray Machine Components X-ray Machine Components X-ray Tubehead Control Panel 110, 220 line Timer Exposure switch mA selector kVp selector Autotransformer Step-down transformer Step-up transformer X-ray Tube Wires Oil Engineering World Health (2015), Great X-Ray Presentation. Retrieved from library.ewh.org

60-cycle Alternating Current + 110, 220 positive - 110, 220 negative Direct Current (Constant Potential): 800 cycles/sec. Engineering World Health (2015), Great X-Ray Presentation. Retrieved from library.ewh.org

Number of Impulses Seconds = 60 60 impulses/60 = 1.0 second 1/60 Number of Impulses 60 = Seconds 60 impulses/60 = 1.0 second 30 impulses/60 = 0.5 second 15 impulses/60 = 0.25 second Engineering World Health (2015), Great X-Ray Presentation. Retrieved from library.ewh.org

Exposure Switch Allows current to flow to complete high and low voltage circuits. Indicator light and sound You cannot overexpose by holding the exposure switch down too long! Engineering World Health (2015), Great X-Ray Presentation. Retrieved from library.ewh.org

milliAmpere (mA) selector mA setting OFF 10mA 15mA milliAmpere (mA) selector Filament current Engineering World Health (2015), Great X-Ray Presentation. Retrieved from library.ewh.org

Step-Down Transformer 110 volt 3 – 5 volts Filament Circuit

Step-Down Transformer 110 volts current flow Primary 3-5 volts current flow Secondary Engineering World Health (2015), Great X-Ray Presentation. Retrieved from library.ewh.org

kiloVolt peak (kVp) selector kVp control kVp readout Engineering World Health (2015), Great X-Ray Presentation. Retrieved from library.ewh.org

Autotransformer Controls voltage between anode and cathode Autotransformer Controls voltage between anode and cathode Regulated by kVp selector (Similar to a rheostat)

Autotransformer 110 V current flow 65 V 80 V 110 V current flow 65 V 80 V Engineering World Health (2015), Great X-Ray Presentation. Retrieved from library.ewh.org

Step-Up Transformer 65 - 90 V 65,000 - 90,000 V (65 kVp - 90 kVp) Step-Up Transformer 65 - 90 V 65,000 - 90,000 V (65 kVp - 90 kVp) kVp = kiloVoltage peak

Step-Up Transformer Primary Secondary 110 volts 65,000 to 90,000 volts Step-Up Transformer 110 volts current flow Primary 65,000 to 90,000 volts current flow Secondary Engineering World Health (2015), Great X-Ray Presentation. Retrieved from library.ewh.org

X-ray Machine Components oil exposure button filament filter Engineering World Health (2015), Great X-Ray Presentation. Retrieved from library.ewh.org

kVp 3-5 volts 65-90 volts filament <110 volts 110 volts 65,000 to kVp 3-5 volts 65-90 volts filament <110 volts 110 volts 65,000 to 90,000 volts Engineering World Health (2015), Great X-Ray Presentation. Retrieved from library.ewh.org

X-ray Production 3 Engineering World Health (2015), Great X-Ray Presentation. Retrieved from library.ewh.org

Exposure Factors kVp mA Exposure time

kVp (kiloVolt peak) Number of X-rays X-ray Energy (keV) 90 kVp 70 kVp 90 kVp Number of X-rays 70 kVp maximum energy 70 90 average energy X-ray Energy (keV) Engineering World Health (2015), Great X-Ray Presentation. Retrieved from library.ewh.org

Increasing kVp results in: Increasing kVp results in: Higher average energy of x-rays Greater maximum energy x-rays More x-rays

mA (milliamperes) Number of X-rays X-ray Energy (keV) 10 mA 5 mA 10 mA Number of X-rays 5 mA maximum energy (no change) 70 X-ray Energy (keV) average energy (no change) Engineering World Health (2015), Great X-Ray Presentation. Retrieved from library.ewh.org

Exposure time Number of X-rays X-ray Energy (keV) 10 impulses 10 impulses Number of X-rays 5 impulses maximum energy (no change) 70 X-ray Energy (keV) average energy (no change) Engineering World Health (2015), Great X-Ray Presentation. Retrieved from library.ewh.org

Increasing mA or Exposure Time results in: Increasing mA or Exposure Time results in: An increase in the number of x-rays produced No change in the energy of the x-ray beam

mAs or mAi milliamperes (mA) x seconds (s) milliamperes (mA) x impulses (i) 60 impulses = 1 second 10 mA x .5 seconds = 5 mAs 20 mA x .25 seconds = 5 mAs mAi = 60 x mAs

Collimation Regulates the size and/or shape of the x-ray beam Regulates the size and/or shape of the x-ray beam area covered (less patient exposure) scatter radiation

Scatter Radiation primary x-ray scattered x-ray primary x-ray scattered x-ray Engineering World Health (2015), Great X-Ray Presentation. Retrieved from library.ewh.org

Collimation front views side view collimated beam collimator target front views side view collimated beam collimator target (x-ray source) 2.75 inches (7 cm) = maximum diameter of circular beam or maximum length of long side of rectangular beam at end of PID. Engineering World Health (2015), Great X-Ray Presentation. Retrieved from library.ewh.org

Quality average energy Quantity number of x-rays

Inverse Square Law The intensity of radiation varies inversely as the square of the target-film distance * * target = source, focal spot, focus

Engineering World Health (2015), Great X-Ray Presentation. Retrieved from library.ewh.org

Inverse Square Law D D 1 1 100 10 1 100 UI = KI UI 2 X KI = 2 Inverse Square Law D 2 KI X KI = UI D UI 2 1 1 100 = 10 1 100 X 100 = 1 Engineering World Health (2015), Great X-Ray Presentation. Retrieved from library.ewh.org

? Questions?