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
- The probe connected to the & rsquo; apparatus by a cable.
- L & rsquo; screen on which video images are viewed live.
- The computer system
- The control panel, composed of multiple
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 :
– LINEAR,SECTOR, ELECTRONIC OR MECHANICAL CONVEX
PROBE PROBE orificial OR DO VOID :
– TRANS OESOPHAGIENNE
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 :
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
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 ?
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"
E = electrode (electrical excitation)
Q= quartz : = crystal material elastic body
P = plate carrying the material
FEATURE OF THE MATERIAL
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
- 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.
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
MODE A and B
MODE A :
Saving as PIC d & rsquo; amplitude :
– 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.
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
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.
Terms used to define the characteristics of the ultrasonic & rsquo; image obtained by the piezoelectric method
– Interface, Wall
– posterior enhancement
C & rsquo; is a separation zone between two media of & rsquo; different acoustic impedance (c & rsquo; is a limit). It is echogenic
The wall is a reflective structure between two same impedance settings
Ex : gallbladder wall, bladder, vascular
L & rsquo; acoustic shadow is due to a total reflection of the US the following substances :
AIR/ OS/ CALCIFICATIONS
Echostructure D & rsquo; A Mileu
L & rsquo; echo-structure & rsquo; a medium is its sonographic appearance or texture according to its sonographic different structures which composes.
ENVIRONMENT MAY BE:
– hyper-middle réfléchisant (rich in echoes point) said hyperechoic
– reflectance medium : presence of”echoes and the medium is said to be echogenic
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.
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 :
Morphology, cut, echogenicity and vascular marker splenic vein and artery mésentétique
– 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
– 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.
1/The principle of & rsquo; ultrasound PIERRON 2011
2/ L & rsquo; ultrasound : principle and procedure. GRALON 2008
Dr Lecheheb's course – Faculty of Constantine