Física básica del ultrasonido
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Transcript of Física básica del ultrasonido
DEPARTAMENTO DE VENTAS
DEPARTAMENTO DE VENTAS
DEFINICIONES
HISTORIA
TRANSDUCTORES
MODOS DE IMAGEN
MODO A
MODO M
MODO B
MODO DOPPLER
MODO CW
MODO PW
MODO COLOR
POWER DOPPLER
MODO POWER DIRECCIONAL
IMAGEN PANORAMICA
3D/4D
DEPARTAMENTO DE VENTAS
CONCEPTOS BÁSICOS DEL SONIDO
DEPARTAMENTO DE VENTAS
Sonido es una onda mecánica longitudinal que se propaga a través de un medio elástico.
DEPARTAMENTO DE VENTAS
Compresión: Región de alta presión. Rarefacción: Zonas de baja presión. Las compresiones y rarefacciones se alternan a través del medio en la misma forma que las partículas de aire individuales oscilan de un lado a otro en la dirección de la propagación de la onda.
DEPARTAMENTO DE VENTAS
AMPLITUD: Es el valor máximo del movimiento de una onda.
PERIODO: Tiempo que se tarda
en realizar un ciclo completo. Se mide en segundos (s).
FRECUENCIA: Es el número de ciclos que se realizan en un segundo. Es, por tanto, la inversa del período:
f = 1 / T Se mide en ciclos por
segundo (cps), que se denomina normalmente hercios (Hz).
DEPARTAMENTO DE VENTAS
LONGITUD DE ONDA: La distancia que recorre una onda sonora en el tiempo de un período es lo que se llama longitud de onda (λ).
VELOCIDAD DEL SONIDO: Es la velocidad con que se desplazan las ondas sonoras. Su dirección es perpendicular a la superficie vibrante bajo forma de ondas.
Velocidad = Distancia recorrida / tiempo
c = λ * f
DEPARTAMENTO DE VENTAS
Medium Velocity (m/s) Medium Velocity (m/s)
Air 330 Liver 1549
Water 1480 Kidney 1561
Fat 1450 Muscle 1585
DEPARTAMENTO DE VENTAS
Infrasound Audible Sound Ultrasound 20Hz 20kHz
For medical diagnostic imaging
1MHz 20MHz
Low High
FRECUENCIAS
DEPARTAMENTO DE VENTAS
Piezoelectricity crystal
DEPARTAMENTO DE VENTAS
1910s Ultrasound sonar theory was developed in France
1942 A mode was invented in Austria for brain scanning
1950s M mode was invented
USA invented B mode in clinical application
1956 CW mode was invented in Japan for heart valve
application
1959 PW mode was invented
1983 Color Doppler mode was invented in Japan
1990 Kretz, an Austria company made the first commercial 3D
ultrasound scanner
DEPARTAMENTO DE VENTAS
1910s
DEPARTAMENTO DE VENTAS
DESCRIPCION DE CADA UNO DE ELLOS
DEPARTAMENTO DE VENTAS
A=AMPLITUD
SOLO SE REGISTRA LA INTENSIDAD DE LA SEÑAL DEL ECO.
M: Motion displayed over time
Time
Depth
Function: to display tissue motion 1950s DEPARTAMENTO DE VENTAS
B: Brightness • displayed as dots on screen • stronger signal, brighter dot
Function: to display tissue structure
B mode is also called 2D mode.
1950s DEPARTAMENTO DE VENTAS
Convex Probe
Linear Convex
Phased array probe Linear probe
DEPARTAMENTO DE VENTAS
DEPARTAMENTO DE VENTAS
DESCRIPCION DE CADA UNO DE ELLOS
Austria
Physicist and mathematician
Born in 1803 in Salzburg
Found Doppler Principle in 1842
Died in 1853 in Venice
DEPARTAMENTO DE VENTAS
Sound source: NOT moving Sound source: moving
DEPARTAMENTO DE VENTAS
DEPARTAMENTO DE VENTAS
Blood cell NOT moving Blood cell moving forward/backward
DEPARTAMENTO DE VENTAS
θ
v
f f + fD c
cos2D
vff
fD: Doppler shift of the frequency
f: Transmitted frequency
v: Velocity of the blood
θ: Angle of incidence between the
ultrasound beam and the direction of the
flow
c: speed of sound in tissue
DEPARTAMENTO DE VENTAS
Color Doppler:
1. Color: Color Doppler
2. Power: Power Doppler:
3. Directional Power Doppler
Spectral Doppler:
1. CW: continuous wave Doppler
2. PW: Pulse wave Doppler
Color Doppler
Spectral Doppler
DEPARTAMENTO DE VENTAS
Color Doppler: Pixels assigned color based on mean velocity
Function: to display direction of blood flow
Color mode is also called CDFI mode (Color Doppler Flow Imaging) or CFM (color flow mapping)
Red towards probe Blue away from probe
1983 DEPARTAMENTO DE VENTAS
Power Doppler: Pixels assigned color based on mean power
Function: to display volume of blood flow, especially at low velocity
Power mode is also called CPA mode. (Color Power Angio)
DEPARTAMENTO DE VENTAS
DEPARTAMENTO DE VENTAS
DEPARTAMENTO DE VENTAS
Gray Scale Velocity Variance Power Directional Power
B mode Color mode Power mode
B mode - colorized Color mode
Whole image is colorized. Only blood flow is colorized. Tissue is monochrome.
DEPARTAMENTO DE VENTAS
Sensitivity
Direction
Velocity
Angle dependent
Application
Yes
Yes
Yes
Normal velocity
No
No
No
Low velocity
Normal High
Color Power
Yes
No
No
Low velocity
High
DirPower
Power Doppler displays amplitude of signal (how much) Color Doppler displays velocity (how fast)
DEPARTAMENTO DE VENTAS
Color mode
vertical oblique
Power mode
Angle Dependent Yes No
At perpendicular angle No flow displayed Displayed normally
DEPARTAMENTO DE VENTAS
Some elements are transmitting sound waves.
The transmitting and receiving of sound waves are JUST in the same time.
But there is a sensitive region.
The others are receiving.
There is NO Sample Volume.
DEPARTAMENTO DE VENTAS
DEPARTAMENTO DE VENTAS
Sensitive Region
Angle Correction
Sample Line
Gray scale stands for: the amount of all objects in that velocity along the sample line.
CW: Continuous-Wave Doppler speed of blood cells displayed on a time/velocity graph
Function: to measure velocity of blood flow, especially in heart
Time
Velocity
1956 DEPARTAMENTO DE VENTAS
Elements are both transmitting and receiving sound waves.
The transmitting and receiving of sound waves are NOT in the same time.
There is a Sample Volume.
PRF: Pulse Repetition Frequency Transmit Receive Transmit Receive …
DEPARTAMENTO DE VENTAS
DEPARTAMENTO DE VENTAS
Sample Volume
Angle Correction
Sample Line
Gray scale stands for: the amount of all objects in that velocity in the sample volume.
PW: Pulse-Wave Doppler
Function: to measure velocity of blood flow
Time
Velocity
1959 DEPARTAMENTO DE VENTAS
DEPARTAMENTO DE VENTAS
Principle
Probe
Velocity
Locate
Window
Application
All elements are transmitting and receiving sound waves.
All
Low
Sample volume
Yes
All
Phased array, pencil, other
High
Sample line
No
Cardiology
Pulsed-wave Continuous wave
PW mode CW mode
Some elements are transmitting sound waves. The others are receiving.
Sample Volume
Angle Correction
Sample Line
Sensitive Region
Angle Correction
Sample Line
Principle
Y-axial
Object
Locate
Application
Velocity (cm/s, m/s) frequency shift (kHz)
Hemodynamics
Sample volume
Cardiology, vascular
Depth (cm, mm)
Tissue motion
Sample line
Cardiology
Doppler Pulse-echo
PW mode M mode
DEPARTAMENTO DE VENTAS
Conventional M mode
Anatomical M mode
Along sound beam
DEPARTAMENTO DE VENTAS
DEPARTAMENTO DE VENTAS
DEPARTAMENTO DE VENTAS
Fan
Linear
1990 DEPARTAMENTO DE VENTAS
DEPARTAMENTO DE VENTAS
DEPARTAMENTO DE VENTAS
Network
Imaging System 1
Imaging System 2
Imaging System 3
Reception
DICOM PrinterDoctor
DICOM Server
Diagnostic Center
Verification
Storage Worklist