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Dental Radiology Today

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X-rays ? Electro magnetic spectrum X-ray - - (detector)- The X-rays tube X-ray generator X-ray The X-rays ... – PowerPoint PPT presentation

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Title: Dental Radiology Today


1
?? ????? ??
2
??? ??
  • X-rays??
  • X-rays? ??? ???????
  • X-ray does? ??? ??? ????
  • X-rays? ?? ? ???? ? ?? ?????
  • Digital X-ray? ?????

3
??? X-ray Mrs. Roentgens Hand
4
X-rays??
  • X-rays ???? ?? (????? ??)
  • ?? ?? (300.000 km/s)
  • ?? ?? (light10-6 RX10-10)
  • ????? ?? ???? ??.
  • X rays ? ?? ? ?? ???? ?? ???? ???? ??.

5
Electro magnetic spectrum
6
X-ray ?? ???-???-??(detector)-??
??
???
???
??(DETECTOR)
7
The X-rays tube
Focal area
8
X-ray generator
Hochspannungsanschluß der Anode
Anode
Heizungsanschluß
Fokus
Kathode
9
X-ray ??
10
The X-rays Tube head
??? ???
??? anode x-ray tube
?? ???
Beam ?? ?? ?? (cone).
? ??
safety and protection devices
11
?? ?? ?? ??
12
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 ??? ????.
  • ??? ?? ??? ??? ?? ?? ??? ?? ???.

13
Impact of mA on the image
  • mA? ???? ??? ??? ??? ? ??.
  • (mA ??)

14
Impact of kV on the image
  • kV? ???(contrast)? ????.
  • (kV ??)

15
?? Focal Spot? ???
FOCAL SPOT X-ray ?? ??
16
The importance of a small Focal Spot
object
17
Geometry Positioning and Sharpness
large focal spot
large focal spot
???? ??(detector)? ?????? ???? ????.
object
object
detector
detector
??? ??? ??
??? ??
18
Collimation(??)
  • x-ray beam? Collimator(???)? ?? ??? ???? ?? ??
    ??? ????.

19
?? ?? ? ??
20
?? ?? ? ??
  • 1) ?? ?? ???? ??? ??????.
  • 2) ??? ???? x-ray? ???? ??? 2?? ???
    ??????.

2 meters
Scattered radiations
21
?? ?? ? ??
  • 1) ?? ?? ???? ??? ??????.
  • 2) Panoramics The x-rays? ???? ??? ????? ???
    ?? ??? ??? 2?? ??? ??????.

2 meters
X-ray
X-ray
Scattered radiations
22
Digital X-Ray
23
Digital ??? ?? ??
X-Ray???? ?? X-ray ?? ? ???? ?? ??? Flim? ????
CDD ?? CMOS ?? ???? ??? Display?? ??? ???? ???
??? ?? ? ??? ??? ??
Sensor
X-ray ???
24
What is a digital x-ray image
Physical definition
Mathematical definition
Digital image
25
Sensors? ???? ??
26
Sensors
PCB Circuits
CCD Array
F/O Screen
Scintilator
27
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

28
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!!!!
29
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
30
Image Quality
11-12 Lp
18-19 Lp
31
(No Transcript)
32
Image Quality
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