1. Ultrasound Principle 超音波原理
Diagnosis Imaging System
影像診斷系統

2. Sound wave l Wavelength 波長 振幅 Amplitude 1 Cycle 週期 Pressure maximum
minimum
1 Cycle 週期

3. Amplitude Frequency Velocity Sound wave dB MHz 1,000,000 次/秒
1540 m/s in body

4. 折射與反射
Propagated
wave
Refracted
Reflected
Medium #1
Medium #2

5. Power and Intensity Power … watt Intensity… watt / cm2
Loudness or strength
Decibel notation …
Gain
dB Intensity Ratio Amplitude Ratio
70 10,000, ,000
60 1,000, ,000 , , ,
dB = 10 log 10 ( ) I I0

6. Frequency Vs Penetration 頻率與穿透力的關係
Reflection
Absorption
Scattering
Frequency
Penetration
結果: 超音波頻率提升,穿透力卻下降

7. 超音波頻率提升解像度也會提升 Higher Frequency can Frequency Vs Resolution 頻率與解像度的關係
Reflect smaller objects
超音波頻率提升解像度也會提升

8. Resolution Spatial Resolution Elevation Axis Lateral Transmit Focusing
Acoustic lance
Matching Layer
Crystal
Absorbing material
Frequency
Transmit
Signal process
Focusing
Steering
Channel ….

9. Resolution Contrast Resolution Dynamic Range Strong reflection
Compress
Dynamic
Range
Expand
Soft Tissue
Weak
Compress
reflection
Visual light
Acoustic Signal

10. Beamfomer
Transducer

11. Beamfomer

12. Signal process

14. B Mode Color Flow Image Doppler Spectrum
Anatomy
Information
Management
B Mode
Color
Flow
Image
Doppler
Spectrum
Function
Viability

15. Signal process / Control
TGC
Dynamic
Range
Focus
Depth
Gain