Title: Dental Radiology Today
1?? ????? ??
2??? ??
- X-rays??
- X-rays? ??? ???????
- X-ray does? ??? ??? ????
- X-rays? ?? ? ???? ? ?? ?????
- Digital X-ray? ?????
3??? X-ray Mrs. Roentgens Hand
4X-rays??
- X-rays ???? ?? (????? ??)
- ?? ?? (300.000 km/s)
- ?? ?? (light10-6 RX10-10)
- ????? ?? ???? ??.
- X rays ? ?? ? ?? ???? ?? ???? ???? ??.
5Electro magnetic spectrum
6X-ray ?? ???-???-??(detector)-??
??
???
???
??(DETECTOR)
7The X-rays tube
Focal area
8X-ray generator
Hochspannungsanschluß der Anode
Anode
Heizungsanschluß
Fokus
Kathode
9X-ray ??
10The X-rays Tube head
??? ???
??? anode x-ray tube
?? ???
Beam ?? ?? ?? (cone).
? ??
safety and protection devices
11?? ?? ?? ??
12Note Technical factors
- The X-ray dose ? ??? ??? ??? ??.
- Dose kV , mA , sec
- Voltage (kV)?X-ray beam energy level? ????.
- Current (mA) ?? ??? ??? ?? ??? ?? ????.
- Seconds (sec) ?? ??? ????.
- ??? ?? ?
- ??? ??? ??? ?? ?? kV? mA??? contrast ??? ????.
- ??? ?? ??? ??? ?? ?? ??? ?? ???.
13Impact of mA on the image
- mA? ???? ??? ??? ??? ? ??.
- (mA ??)
14Impact of kV on the image
- kV? ???(contrast)? ????.
- (kV ??)
15?? Focal Spot? ???
FOCAL SPOT X-ray ?? ??
16The importance of a small Focal Spot
object
17Geometry Positioning and Sharpness
large focal spot
large focal spot
???? ??(detector)? ?????? ???? ????.
object
object
detector
detector
??? ??? ??
??? ??
18Collimation(??)
- 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
22Digital X-Ray
23Digital ??? ?? ??
X-Ray???? ?? X-ray ?? ? ???? ?? ??? Flim? ????
CDD ?? CMOS ?? ???? ??? Display?? ??? ???? ???
??? ?? ? ??? ??? ??
Sensor
X-ray ???
24What is a digital x-ray image
Physical definition
Mathematical definition
Digital image
25Sensors? ???? ??
26Sensors
PCB Circuits
CCD Array
F/O Screen
Scintilator
27Digital 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
-
28D 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!!!!
29KaVo 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
30Image Quality
11-12 Lp
18-19 Lp
31(No Transcript)
32Image Quality