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BIOMEDICAL INSTRUMENTATION

Name: Mr. T.balasubramanian

Designation: Assistant Professor

Department: Electrical and Electronics Engineering

Subject code: EI 6

!ear: I"

#nit: I"

Title: MEDI$A% IMA&IN&

1

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Radio graphic and l!oro"copic techni#!e" Co$p!ter

to$ograph% MRI Ultra"onograph% Endo"cop%

Ther$ograph% Dierent t%pe" o &iotele$etr% "%"te$"and patient $onitoring Introd!ction to Bio$etric "%"te$"

MEDI$A% IMA&IN& AND PMS

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X-ray machine

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An X-ray machine is a device used by radiographer" is a device

used by radiographers to acquire an '(ra% is a device used by

radiographers to acquire an x-ray image. They are used in variousfields, notably $edicineis a device used by radiographers to acquire

an x-ray image. They are used in various fields, notably medicine and

"ec!rit%.

An X-ray imaging system consists of a X-ray source or generator (

)(ra% t!&eAn X-ray imaging system consists of a X-ray source or

generator (X-ray tube), and an image detection system hich can

either be comprised of film (analog technology) or a digital capture

system (such as a pict!re archi*ing and co$$!nication "%"te$).

(Cont)

http://en.wikipedia.org/wiki/Radiographerhttp://en.wikipedia.org/wiki/X-rayhttp://en.wikipedia.org/wiki/Medicinehttp://en.wikipedia.org/wiki/Securityhttp://en.wikipedia.org/wiki/X-ray_tubehttp://en.wikipedia.org/wiki/Picture_archiving_and_communication_systemhttp://en.wikipedia.org/wiki/Picture_archiving_and_communication_systemhttp://en.wikipedia.org/wiki/X-ray_tubehttp://en.wikipedia.org/wiki/Securityhttp://en.wikipedia.org/wiki/Medicinehttp://en.wikipedia.org/wiki/X-rayhttp://en.wikipedia.org/wiki/Radiographer

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!n the typical X-ray source of less than "#$ %&, )(ra%!n the

typical X-ray source of less than "#$ %&, X-ray photons are

produced by an electron &ea$!n the typical X-ray source of

less than "#$ %&, X-ray photons are produced by an electronbeam stri%ing a target. The electrons that ma%e up the beam are

emitted from a heated cathode filament. The electrons are then

focused and accelerated toards an angled anode target. The

point here the electron beam stri%es the target is called the

focal spot. 'ost of the +inetic energ%contained in the electron

beam is converted to heat, but around of the energy is

converted into X-ray photons, the excess heat is dissipated via a

heat sin%. At the focal spot, X-ray photons are emitted in all

directions from the target surface, the highest intensity beingaround *$deg to +$deg from the beam due to the angle of the

anode target to the approaching X-ray photons. There is a small

round indo in the X-ray tube directly above the angled

target. This indo allos the X-ray to exit the tube ith littleattenuation hile maintaining a vacuum seal required for the

http://en.wikipedia.org/wiki/X-rayhttp://en.wikipedia.org/wiki/Electron_beamhttp://en.wikipedia.org/wiki/Kinetic_energyhttp://en.wikipedia.org/wiki/Kinetic_energyhttp://en.wikipedia.org/wiki/Electron_beamhttp://en.wikipedia.org/wiki/X-ray

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X-ray machines or% by applying controlled *oltageX-ray

machines or% by applying controlled voltage and c!rrent

X-ray machines or% by applying controlled voltage and

current to the )(ra% t!&eX-ray machines or% by applyingcontrolled voltage and current to the X-ray tube, hich

results in a beam of )(ra%"X-ray machines or% by

applying controlled voltage and current to the X-ray tube,

hich results in a beam of X-rays. The beam is proected on

$atterX-ray machines or% by applying controlled voltage

and current to the X-ray tube, hich results in a beam of X-

rays. The beam is proected on matter. ome of the X-ray

beam ill pass through the obect, hile some are absorbed.

The resulting pattern of the radiation is then ultimately

(Cont)

http://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/X-ray_tubehttp://en.wikipedia.org/wiki/X-rayhttp://en.wikipedia.org/wiki/Matterhttp://en.wikipedia.org/wiki/Rare_earth_elementhttp://en.wikipedia.org/wiki/Matterhttp://en.wikipedia.org/wiki/X-rayhttp://en.wikipedia.org/wiki/X-ray_tubehttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/Voltage

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X-ray machines are used in health careX-ray machines are

used in health care for visualising bone structures and other

dense tissues such as t!$o!r"X-ray machines are used in

health care for visualising bone structures and other dense

tissues such as tumours. on-medicial applications include

"ec!rit%and material analysis.

(Cont)

http://en.wikipedia.org/wiki/Health_carehttp://en.wikipedia.org/wiki/Tumourhttp://en.wikipedia.org/wiki/Securityhttp://en.wikipedia.org/wiki/Securityhttp://en.wikipedia.org/wiki/Tumourhttp://en.wikipedia.org/wiki/Health_care

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/adio graphic and fluoroscopic techniques

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!n the typical radiographic examination the x-ray beam is

proected through the patient0s body

The point that receives maximum exposure is the entrance

surface near the center of the beam. There are to reasons

for this. The primary x-ray beam has not been attenuated by

the tissue at this point, and the area is exposed by some of

the scattered radiation from the body. The amount of

surface exposure produced by the bac%scatter depends onthe spectrum of the primary beam and the si1e of the

exposed area. 2or typical radiographic situations, scattered

radiation can add at least 3$ to the surface exposure

produced by the primary beam.

(Cont)

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As the x-ray beam progresses through the body, it undergoes

attenuation. The rate of attenuation (or penetration) isdetermined by the photon-energy spectrum (4& and filtration)

and the type of tissue (fat, muscle, bone) through hich the

beam passes. 2or the purpose of this discussion, e assume a

body consisting of homogeneous muscle tissue. !n the

folloing figure, lines are dran to divide the body into

5&6s. The exposure is reduced by a factor of one half each

time it passes through 5&6. The thic%ness of 5&6

depends on the photon-energy spectrum. 5oever, for the

immediate discussion, e assume that 5&6 is equivalent to "cm of tissue. A 3$-cm thic% body section consists of # 5&6s.

Therefore, the exposure decreases by one half as it passes

through each " cm of tissue. At the exit surface, the exposure is

a small fraction of the entrance surface exposure.

(Cont)

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The fluoroscopic beam proected through the body ill

produce a pattern similar to a radiographic beam if the beam

remains fixed in one position. !f the beam is moved duringthe procedure, the radiation ill be distributed over a large

volume of tissue rather than being concentrated in one area.

2or a specific exposure time, tissue exposure values

(roentgens) are reduced by moving the beam, but the total

radiation (/ - cm3) into the body is not changed. This asillustrated in the figure titled, 78xposure7 (in the section

titled, 7/adiation 9uantities and :nits7).

Fluoroscopic techniques

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Computer tomography

!n computed tomography (;T) to factors are associated ith

exposure distribution and must be considered< () the

distribution ithin an individual slice and (3) the effect of

imaging multiple slices.

The rotation of the x-ray beam around the body produces a

much more uniform distribution of radiation exposure than a

stationary radiographic beam. A typical ;T exposure pattern is

shon in the figure belo. A relatively uniform distribution

throughout the slice is obtained if a =*$> scan is performed.

5oever, if other scan angles that are not multiples of =*$> are

used, the exposure distribution ill become less uniform.

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?hen multiple slices are imaged, the dose (grays) does not

increase in proportion to the number of slices because the

radiation is distributed over a larger volume of tissue.5oever, hen slices are located close together, radiation

from one slice can produce additional exposure in adacent

slices because slice edges are not sharply defined and because

of scattered radiation.

(Cont)

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'/! scanners, li%e X-raysand CT scanners, are basically

machines doctors use to ta%e pictures of your insides so

that they can figure out hat@s ailing you. ut '/! doesn@t

involve ioni1ing radiation, as do X-rays and ;T scans./ather, '/! ta%es advantage of something you have plenty

of in your body< ater. !t is far more flexible than X-rays

and ;T scans, and can generate three dimensional images

in any orientation and at any depth in the body.

Magnetic Resonance Imaging('/!)

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'/! scanner

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Magnetic Resonance Imaging (MRI), or nuclear magnetic

resonance imaging(NM'I), is primarily a $edical i$aging), is

primarily a medical imaging technique most commonly used in

radiolog%), is primarily a medical imaging technique most

commonly used in radiology to visuali1e the internal structure

and function of the body. '/! provides much greater contra"t),

is primarily a medical imaging technique most commonly used in

radiology to visuali1e the internal structure and function of thebody. '/! provides much greater contrast beteen the different

soft tissues of the body than co$p!ted to$ograph%), is

primarily a medical imaging technique most commonly used in

radiology to visuali1e the internal structure and function of thebody. '/! provides much greater contrast beteen the different

soft tissues of the body than computed tomography (;T) does,

ma%ing it especially useful in ne!rological), is primarily a

medical imaging technique most commonly used in radiology to

visuali1e the internal structure and function of the body. '/!

http://en.wikipedia.org/wiki/2D-FT_NMRI_and_Spectroscopyhttp://en.wikipedia.org/wiki/Medical_imaginghttp://en.wikipedia.org/wiki/Radiologyhttp://en.wikipedia.org/wiki/Contrast_(vision)http://en.wikipedia.org/wiki/Computed_tomographyhttp://en.wikipedia.org/wiki/Neurologyhttp://en.wikipedia.org/wiki/Neurologyhttp://en.wikipedia.org/wiki/Computed_tomographyhttp://en.wikipedia.org/wiki/Contrast_(vision)http://en.wikipedia.org/wiki/Radiologyhttp://en.wikipedia.org/wiki/Medical_imaginghttp://en.wikipedia.org/wiki/2D-FT_NMRI_and_Spectroscopy

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The body is mainly composed of ater molecules hich each

contain to h%drogenThe body is mainly composed of ater

molecules hich each contain to hydrogen n!cleiThe body

is mainly composed of ater molecules hich each contain

to hydrogen nuclei or proton"The body is mainly composedof ater molecules hich each contain to hydrogen nuclei or

protons. ?hen a person goes inside the poerful

$agnetic ield of the scanner, these protons align ith the

direction of the field.A second radio frequency electromagnetic field is then briefly

turned on causing the protons to absorb some of its energy.

?hen this field is turned off the protons release this energy at a

radio frequency hich can be detected by the scanner. The

position of protons in the body can be determined by applying

additional magnetic fields during the scan hich allos an

image of the body to be built up. These are created by turning

gradients coils on and off hich creates the %noc%ing sounds

heard during an '/ scan.

http://en.wikipedia.org/wiki/Hydrogenhttp://en.wikipedia.org/wiki/Atomic_nucleushttp://en.wikipedia.org/wiki/Protonhttp://en.wikipedia.org/wiki/Magnetic_fieldhttp://en.wikipedia.org/wiki/Magnetic_fieldhttp://en.wikipedia.org/wiki/Protonhttp://en.wikipedia.org/wiki/Atomic_nucleushttp://en.wikipedia.org/wiki/Hydrogen

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The upshot is that '/!, for most applications, is far superior to

other imaging tools in providing non-invasive images (and evenchemical information) at high resolution.

(Cont)

Biseased tissue, such as tumors, can be detected because the

protons in different tissues return to their equilibrium state at

different rates. y changing the parameters on the scanner this

effect is used to create contrast beteen different types of bodytissue.

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Ultrasonography

instrument

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Ultrasonograph

y

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Bay in

ultrasoun!

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A general-purpose sonographic machine may be able to be used

for most imaging purposes. :sually specialty applications may

be served only by use of a specialty transducer. 'ost ultrasound

procedures are done using a transducer on the surface of the

body, but improved diagnostic confidence is often possible if atransducer can be placed inside the body. 2or this purpose,

specialty transducers, including endovaginal, endorectal, and

transesophageal transducers are commonly employed. At the

extreme of this, very small transducers can be mounted on smalldiameter catheters and placed into blood vessels to image the

alls and disease of those vessels.

(Cont)

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Cnce the ultrasonic scanner determines these three things, it

can locate hich pixel in the image to light up and to hat

intensity and at hat h!eCnce the ultrasonic scanner

determines these three things, it can locate hich pixel in the

image to light up and to hat intensity and at hat hue if

frequency is processed (see red"hitfor a natural mapping to

hue).

(Cont)

http://en.wikipedia.org/wiki/Huehttp://en.wikipedia.org/wiki/Redshifthttp://en.wikipedia.org/wiki/Redshifthttp://en.wikipedia.org/wiki/Hue

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Transforming the received signal into a digital image may be

explained by using a blan% spreadsheet as an analogy. ?e

imagine our transducer is a long, flat transducer at the top of

the sheet. ?e ill send pulses don the 0columns0 of our

spreadsheet (A, , ;, etc.). ?e listen at each column for anyreturn echoes. ?hen e hear an echo, e note ho long it too%

for the echo to return. The longer the ait, the deeper the ro

(,3,=, etc.). The strength of the echo determines the brightness

setting for that cell (hite for a strong echo, blac% for a ea%echo, and varying shades of grey for everything in beteen.)

?hen all the echoes are recorded on the sheet, e have a

greyscale image.

(Cont)

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"inear #rray Trans!ucer

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:ltrasonography ("onograph%:ltrasonography (sonography)

uses a probe containing one or more acoustic tran"d!cer"

:ltrasonography (sonography) uses a probe containing one or

more acoustic transducers to send pulses of sound into a

material. ?henever a sound ave encounters a material ith adifferent density (acoustical impedance), part of the sound ave

is reflected bac% to the probe and is detected as an echo. The

time it ta%es for the echo to travel bac% to the probe is

measured and used to calculate the depth of the tissue interfacecausing the echo. The greater the difference beteen acoustic

impedances, the larger the echo is. !f the pulse hits gases or

solids, the density difference is so great that most of the acoustic

energy is reflected and it becomes impossible to see deeper.

(Cont)

http://en.wikipedia.org/wiki/Sonographyhttp://en.wikipedia.org/wiki/Transducerhttp://en.wikipedia.org/wiki/Echo_(phenomenon)http://en.wikipedia.org/wiki/Echo_(phenomenon)http://en.wikipedia.org/wiki/Transducerhttp://en.wikipedia.org/wiki/Sonography

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Mo!es o$ sonography

Four !i$$erent mo!es o$ ultrasoun! are use! in me!ical

imaging%These are