Dental Radiology Today

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?? ????? ??
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??? ??

• X-rays??
• X-rays? ??? ???????
• X-ray does? ??? ??? ????
• X-rays? ?? ? ???? ? ?? ?????
• Digital X-ray? ?????

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??? X-ray Mrs. Roentgens Hand
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X-rays??

• X-rays ???? ?? (????? ??)
• ?? ?? (300.000 km/s)
• ?? ?? (light10-6 RX10-10)
• ????? ?? ???? ??.
• X rays ? ?? ? ?? ???? ?? ???? ???? ??.

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Electro magnetic spectrum
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X-ray ?? ???-???-??(detector)-??
??
???
???
??(DETECTOR)
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The X-rays tube
Focal area
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X-ray generator
Hochspannungsanschluß der Anode
Anode
Heizungsanschluß
Fokus
Kathode
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X-ray ??
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The X-rays Tube head
??? ???
??? anode x-ray tube
?? ???
Beam ?? ?? ?? (cone).
? ??
safety and protection devices
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?? ?? ?? ??
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Note Technical factors

• The X-ray dose ? ??? ??? ??? ??.
• Dose kV , mA , sec
• Voltage (kV)?X-ray beam energy level? ????.
• Current (mA) ?? ??? ??? ?? ??? ?? ????.
• Seconds (sec) ?? ??? ????.
• ??? ?? ?
• ??? ??? ??? ?? ?? kV? mA??? contrast ??? ????.
• ??? ?? ??? ??? ?? ?? ??? ?? ???.

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Impact of mA on the image

• mA? ???? ??? ??? ??? ? ??.
• (mA ??)

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Impact of kV on the image

• kV? ???(contrast)? ????.
• (kV ??)

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?? Focal Spot? ???
FOCAL SPOT X-ray ?? ??
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The importance of a small Focal Spot
object
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Geometry Positioning and Sharpness
large focal spot
large focal spot
???? ??(detector)? ?????? ???? ????.
object
object
detector
detector
??? ??? ??
??? ??
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Collimation(??)

• x-ray beam? Collimator(???)? ?? ??? ???? ?? ??
  ??? ????.

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?? ?? ? ??
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?? ?? ? ??

• 1) ?? ?? ???? ??? ??????.
• 2) ??? ???? x-ray? ???? ??? 2?? ???
  ??????.

2 meters
Scattered radiations
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?? ?? ? ??

• 1) ?? ?? ???? ??? ??????.
• 2) Panoramics The x-rays? ???? ??? ????? ???
  ?? ??? ??? 2?? ??? ??????.

2 meters
X-ray
X-ray
Scattered radiations
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Digital X-Ray
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Digital ??? ?? ??
X-Ray???? ?? X-ray ?? ? ???? ?? ??? Flim? ????
CDD ?? CMOS ?? ???? ??? Display?? ??? ???? ???
??? ?? ? ??? ??? ??
Sensor
X-ray ???
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What is a digital x-ray image
Physical definition
Mathematical definition
Digital image
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Sensors? ???? ??
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Sensors
PCB Circuits
CCD Array
F/O Screen
Scintilator
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Digital X-ray Image Quality

• Depends on
• Sensitivity of system - higher is
  better-(Electronics)
• Resolution - Line pairs per millimeter higher
  (Pixel Size)
• S/N ratio - higher is better- (Electronics)
• Dynamic Range higher is better
  (SensorElectronics)
• Quanti Steps - Hardware/Software

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D X-ray Image Quality
Quantization (Quanti) Steps (Levels of
gray) 01010101010101010101 10 bit 1,024 12
bit 4,096 16 bit 65,536 32 bit
4,294,967,296 8 bit 256 Normal PC screen can
only display 8 bits of information!!!!
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KaVo Sensor Resolution
KaVo Pan eXam 1000 Resolution CCD Pixel Size
48 microns lp/mm 1000/(48x2) 96 10.416
lp/mm Actual approx 10.4lp/mm
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Image Quality
11-12 Lp
18-19 Lp
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Image Quality