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C & rsquo; WHAT IS L & rsquo; ULTRASOUND ?

L & rsquo; d & Ultrasound is a technical rsquo; medical imaging section which uses ultrasound. This name refers to both the & rsquo; medical procedure and the & rsquo; resulting image PRESENTATION & rsquo; IMAGES ultrasound


Embryo fetus →

What should know -on ?

TYPE D & rsquo; UNIT

– Ultrasound

– Various types of probe

L & rsquo; d & rsquo machine; ultrasound s & rsquo; calls : Ultrasound

  1. The probe connected to the & rsquo; apparatus by a cable.
  2. L & rsquo; screen on which video images are viewed live.
  3. The computer system
  4. The control panel, composed of multiple


keys and applications

ultrasonic sensor or probe or ultrasonic transducer :

– essential tool of the & rsquo; equipment.

– With several types of scan, l & rsquo; ultrasound imaging of structures may be obtained.

dynamic electronic focusing :

– Used almost systematically on all d & rsquo sensors, imaging that & rsquo; they are electronic or mechanical scanning.

GEOMETRIC SHAPED DIFFERENT :

– LINEAR,SECTOR, ELECTRONIC OR MECHANICAL CONVEX

SFN OR BROADBAND FREQUENCY

PROBE PROBE orificial OR DO VOID :

– RECTAL

– VAGINAL

– TRANS OESOPHAGIENNE

ULTRASOUND endocardial

PROSTATE.

BRIEF HISTORY :

US used during the * * World War (detecting submarines).

The doctor J.J. Wild and electronics J. Red, have developed the first ultrasound in 1951.

Mode A : 1is mode and 1is recording

For the particular Neuroradiology (research brain tumors. Subdural hematoma compression signs HIC) and ophthalmology

Currently, l & rsquo; ultrasound "a review of st:

– Reference and first-line all the medical field.

ULTRASOUND PRINCIPLE :

Based on :

The method chosen exclusively used in the medical field

1/ ultrasonic beam (US incident beam) How -it generated ?

2/ US interactions between the beam and the material Reflection, Refraction, Diffusion, Mitigation.

3/ Formation of & rsquo; Image How is made the & rsquo; ultrasound image?

4/ Format of the points echo
Registration point echo : Mode A / Mode B or Gloss = 2 D

ULTRA SONS :

DEFINITION :


RANGE OF FREQUENCY IN THE MEDICAL FIELD TOLERABLE: 1MHz 20 MHZ OR 25MHZ

1 HZ = 1 cycle / second
1 KHZ = 103 = 1000 HZ
1 MHZ = 106 = 1000 000 HZ
1GHZ 109 = 1000 000 000 HZ

FREQUENCY : F

PERIOD : T

F= 1/T

SPREAD D & rsquo; WAVE ULTRASOUND :

The length d & rsquo; wave (l) depends on the middle of the mechanical characteristics (propagation velocity : C)

C= 1540m /s
For 1 MHZ / l = 1,54 mm
d & rsquo length; wave :λ = C/F

+ λ is small, + the frequency is high, + the spatial resolution is good

GETS ON HOW-BEAM US ?

PIEZOELECTRIC EFFECT+++++

C & rsquo; WHAT IS ?

Various methods have been described, but the one adopted for the & rsquo; ultrasound imaging and retained in the medical domaim is : piezoelectric phenomenon. :

Discovered by Pierre and Jacques curies brothers

1880 . This basic phenomenon electromechanical transducing, is defined as:

"An oscillating electric potential alternately contract and dilate a crystal producing ultrasonic vibrations"

"The reflection of the US waves on the crystal (nature of the crystal : quartz) produced at & rsquo; reverse a measurable electric current. »

DRAWING UP THE TRANSDUCER

E = electrode (electrical excitation)

Q= quartz : = crystal material elastic body

P = plate carrying the material

FEATURE OF THE MATERIAL

RESILIENT BODY

ACOUSTIC IMPEDANCE (FROM)

FROM : Characterized the mechanical properties of & rsquo; an environment in & rsquo; against pressure waves that s & rsquo; there spread.

Better transmission of the US in the tissues if the & rsquo; lead impedance is close to that tissue.

FROM : Is represented by formula :

Z = RHOxV

Rho : medium density

V : sound propagation velocity in the medium

Formation of US incident beam

  • beam forming US s & rsquo; obtained by exciting the quartz material cut lamella sousforme , d & rsquo; thick given by a discontinuous electric current.
  • When & rsquo; alternating electric pulse, the material (elastic body) contracts and expands synchronously and & rsquo; received electric power is transformed into mechanical vibratory energy that represents the US beam incident whose frequency is a function of & rsquo; thickness and the shape of the quartz.

BEAM INCIDENTUS

TRAINING POINT POWER POINT SAYS ECHO

– L & rsquo; piezoelectric effect is characterized by its reversibility.

– The incident beam reflects æ in contact & rsquo; a d & rsquo interface; medium.

– The resulting reflected beam is responsible for the & rsquo; brief excitement of new material (quartz) ergendrant and the electrically forming said dot echo transcribed sousforme point on & rsquo; screen.

– L & rsquo; interface determines the change d & rsquo; acoustic impedance which characterizes the medium traversed.

– Between two circles ZI and Z2 d & rsquo; impedance close, reflection is low

– Reflection is important if the & rsquo; impedance is different.

ENREGISTREMENTSELON

MODE A and B

MODE A :

Saving as PIC d & rsquo; amplitude :

ECHO A.

– User & rsquo; initial echoes point and applying recording Neurosurgery and Ophthalmology.

The mode "A" (mode amplitude) is the oldest.

in ophthalmology :

– still used in ophthalmology

– It is to interpret the inflections d & rsquo; a line relative to a baseline, each structure of the & rsquo; eye resulting in a peak or series of peaks corresponding to the & rsquo; "echo" of this structure.

– US beam emitted in a given direction

– At each change of structure and therefore d & rsquo; acoustic impedance US are partly reflected.

– US reflected exciting the material result in peaks whose height reflects the amount of & rsquo; energy réflécli

– Choosing & rsquo; a detection threshold allows & rsquo; d & rsquo eliminate permits; eliminate echoes, nonsignificant, below the threshold.

– The distance between 2 peaks allows to know the & rsquo; d & rsquo thickness, structure and the & rsquo; & rsquo absence, echoes between 2 peaks indicates the presence of liquid

Ultrasound and method & rsquo; recording first generation :

– stationary probe in contact with the skin.

– Exploration dimensional vias structures by the incident ultrasonic beam.

MODE B : 2D ECHO

This mode uses the SHINE which defines : each echo point is transcribed as d & rsquo; an electrical or light. The probe is movable.

A two-dimensional image is obtained vias structures.

Luminescence or electrical echo said item registered

two ways :

1) According to the law "all or nothing"

– Echoes exceeding a certain threshold, all recorded in the same way.

– Echoes lower or higher than the threshold of any unregistered.

– Increased or decreased amplitude of echoes by adjusting the gain of & rsquo; unit.

2) Grayscale

Points echoes transcribed according to their intensity as d & rsquo; a range of hue from white to black -White : environment rich in echoes -Black : medium without echo : anechoic -Range gray : intervening media

TREATMENT & rsquo; IMAGE

DISPLAY L & rsquo; IMAGE

REPROGRAPHY

An ultrasound has a complex electronic processing of & rsquo; image having a plurality of subsets :

– A differential amplification (Module TGC : time gain compensation)

– Selecting the dynamic range of the echoes

– Detection and Correction : the negative part of the signal is rectified and displayed Positive

– AD converter and DA (analog / digital and digital / analog)

– A memory

– Post treatment

– Reformatting the data and synchronization

DISPLAY L & rsquo; IMAGE AND REPROGRAPHY

♦ In an oscilloscope, basic hardware signal collection (Point echoes), the electronic scanning of the & rsquo; electrostatic screen is.

♦ In a TV monitor, electronic scanning is obtained by electromagnetism allowing better dynamic gray.

♦ Registration Document : photography / Multi-Image Camera / thermal paper roll : inexpensive system, compact but average quality picture.

SEMANTICS

ultrasound language

Terms used to define the characteristics of the ultrasonic & rsquo; image obtained by the piezoelectric method

– Interface, Wall

– posterior enhancement

– Echo-structure

INTERFACE

C & rsquo; is a separation zone between two media of & rsquo; different acoustic impedance (c & rsquo; is a limit). It is echogenic

Ex : Liver / Diaphragm

WALL

The wall is a reflective structure between two same impedance settings
Ex : gallbladder wall, bladder, vascular

ACOUSTIC SHADOW

L & rsquo; acoustic shadow is due to a total reflection of the US the following substances :

AIR/ OS/ CALCIFICATIONS

Hyperechoic with acoustic shadow characterizing their nature.

Echostructure D & rsquo; A Mileu

DEFINITION :

L & rsquo; echo-structure & rsquo; a medium is its sonographic appearance or texture according to its sonographic different structures which composes.

ENVIRONMENT MAY BE:

SOLID :

– hyper-middle réfléchisant (rich in echoes point) said hyperechoic

– reflectance medium : presence of”echoes and the medium is said to be echogenic

SEMI-LIQUID

Mixed compound liquid dotted d & rsquo; & rsquo echoes; different intensity depending on their nature ex : necrosis d & rsquo; a solid tumor, abscess, hematoma in the process of & rsquo; organization.

fluid PUR

Medium without echoes said anechoic, is characterized by a posterior reinforcement (water, bile, sang)

ENVIRONMENTAL ASPECT :

– homogeneous medium :

structured environment, many present echoes have the same intensity and are regularly distributed.

– heterogeneous environment :

includes macro-structures (fibrous tract, calcifications, necrosis), d & rsquo; different intensity and irregular distribution.



Cup on the pit of the stomach

PANCREAS :

Morphology, cut, echogenicity and vascular marker splenic vein and artery mésentétique

INDICATIONS :

– They are very wide and practiced at any age

– wealthy in antenatal Applications, Neonatology and Pediatrics

– superficial and deep exploration or hollow organ

– New emergency applications

CONCLUSION

– L & rsquo; d & Ultrasound is a technical rsquo; ultrasound imaging that is harmless, non-invasive and non vulnérantes dan: the usual conditions & rsquo; use.

– It is distinguished by a high spatial and temporal resolution.

– It allows a morphological study of explored structures

– It is characterized by a real-time exploration, however, it remains operator dependent.

REFERENCES
1/The principle of & rsquo; ultrasound PIERRON 2011
2/ L & rsquo; ultrasound : principle and procedure. GRALON 2008

Dr Lecheheb's course – Faculty of Constantine