bm 402 lecture notes 2013

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BM 402

ENGINEERING IN MEDICINE

LECTURE NOTES

Ata AKIN

Institute of Biomedical Engineering

Boazii University

2013 by Ata Akn


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PREFACE

These lecture notes are a collage from several books and my own experiences. I would like tothank my former student, Ms Zeynep Susam, for compiling these notes while I was lecturing.She was kind enough to include many pictures and graphics (along with some cartoons) tomake these notes more attractive.


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TABLE OF CONTENTS

INTRODUCTION 4

HISTORYOFMEDICINE 4BRANCHESOFBME 7

AQUICKREVIEWONPHYSIOLOGY&ANATOMY 8

PHYSIOLOGICALSYSTEMS 8

CIRCULATORY(CARDIOVASCULAR)SYSTEM 9

NERVOUSSYSTEM 11

RESPIRATORY(PULMONARY)SYSTEM 14

GASTROINTESTINAL(DIGESTIVE)SYSTEM 15

UROGENITALSYSTEM 16

MUSCULOSKELETALSYSTEM 18

ENDOCRINESYSTEM 19

HEMATOPOIETICSYSTEM&LYMPHATICSYSTEM 21

BIOMEDICALDEVICES 22

BIOMEDICALSENSORS 24

CHEMICALSENSORS 24

CLARKELECTRODE 24

PULSEOXIMETRY 25

BIOCHEMICALSENSORS 25

ELECTRICALMEASUREMENTS 25

ELECTROCARDIOGRAM(ECG) 27

ELECTROMYOGRAM(EMG) 28

ELECTROENCEPHALOGRAM (EEG) 28

PHYSICALMEASUREMENTS 30

VOLUMEMEASUREMENT 30

FORCE&STRAINMEASUREMENT 31

PIEZOELECTRICTRANSDUCER 33

BLOODPRESSUREMEASUREMENT 33

TEMPERATUREMEASUREMENT 34BIOSENSORS 34

BIOMEDICALINSTRUMENTATION 36

DATAPROCESSINGUNIT 36

BIOMEDICALSIGNALPROCESSING 40

FOURIERTRANSFORM 42

MEDICALIMAGING 44

QUALITYINMEDICALIMAGING 44


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RADIATIONIMAGING 45

PHYSICSOFX-RAYIMAGING 47

UNITSOFX-RAYEXPOSURE 48

GEOMETRICUNSHARPNESS 48

COMPUTERAIDETOMOGRAPHYSCANNER(CATSCAN) 49FLUOROSCOPY 51

ANGIOGRAPHY 51

RADIONUCLIDEIMAGING 52

POSITRONEMISSIONTOMOGRAPHY(PETSCAN) 53

RADIOACTIVEDECAY 53

BIOLOGICALHALF-LIFE 54

MAGNETICRESONANCEIMAGING(MRI) 55

PHYSICSOFMRI 55

NUCLEARMAGNETICRESISTANCESPECTROSCOPY(NMRS) 56

LARMORFREQUENCY 56

IMAGINGINMR 58

ULTRASOUNDIMAGING 60

DOPPLERULTRASOUND 63

ECHOCARDIOGRAM 64

THERAPEUTICULTRASOUND 65

BIOMEDICALOPTICS 66

VISIBLELIGHTIMAGING 67

FLUORESCENCEIMAGING 67

THERAPY 68

LASER 68

REHABILITATIONPROCEDURESOFLIGHT 68

REHABILITATIONENGINEERING 70

CLINICALENGINEERING 72

MEDICALETHICS 73


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Introduction

Definition of Biomedical Engineering

Health care delivery team that seeks new (innovative) solutions for the difficult problems

confronting modern society

Innovation patent:

1. Novel no one should have taught about these before

2. Non-(not) obvious

3. Applicable must serve a new purpose

HistoryofMedicine

Primitive medicine (BC 10,000)

They did not have any medication but they were interested in:

Art of herb doctoring

Bone setting

Midwifery

Surgery

They believed that diseases are visitations of evil spirits.

Egyptians (BC 3,000)

Imhotep (peaceful sleep), the architect of the 1st pyramid


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Greek Medicine (BC 500)

God of healing: Aesculapius

Hospitals with tempts

Island of Cos: Hippocrates

o Injected scientific spirit into medicine.

Scientific spirit: systematic approach (cause effect), observation

o He was able to bring diagnostic observation clinical treatment

Romans (AD 500)

To use proper sewer system (public health)

Refrigerated foods (sterile and fresh)

First aid (they were warriors)

Dark Ages

Church dominates medicine

Belief in drugs meant distrust to the healing power of pray

Renaissance (AD 1,500)

Anatomical investigations

Leonardo daVinci Golden Ratio

Florence Nightingale (19th century) (English Nurse)

Hospital conditions accounted more than the diseases in death amounts

She discovered the importance of nursing


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1896Wilhelm Conrad Roentgen discovered X-ray

1901 He won the Nobel Prize

1906 Siemens & General Electric made the first X-ray machine

1914 X-ray machine became mobile and it could work without electric.

1903 Electrocardiogram (ECG)

BranchesofBME

Biomedical Engineering

Diagnostic Systems

- Medical Instrumentation

- Signal / Image Processing

- Nanomedicine

Therapeutic Systems

- Instrumentation

- Prosthetic devices

- Rehabilitation

Clinical Engineering Medical Informatics Biotechnology

- Biosensors


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AQUICKREVIEWonPHYSIOLOGY&ANATOMY

PhysiologicalSystems

A group of interconnected or independent organs that work together to perform a specific

function or a group of functions in the body

System (Transfer) Function

System: processes inputs to produce outputs

HW 1

PART I: Find 2 different definitions of Biomedical Engineering

PART II: Find websites related to Biomedical Engineering and organize them under the

following headings:

1. Academic Websites

2. Industry

3. Professional Organizations

h (t)x (t) y (t)

Physiological

System

Biochemical

Physical

Electrical

Environmental

INPUTS

Biochemical

Physical

Electrical

OUTPUTS


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Lung

Body

SA node

AV node

Circulatory(Cardiovascular)System

Organs: heart, blood vessels

Left Ventricle: Responsible for pumping oxygen rich blood to the body

The heart works with electricity.

Left Atrium

Left Ventricle

Aorta


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SA node has a direct contact from central nervous system to control / modulate the rhythm of

the heart.

Heart rate modulators:

1. Central nervous system

2. Hormonal stimulation

3. Blood flow (mechanical)

4. Biochemical / ionic modulations on a heart muscle

Coronary arteries supply oxygen, glucose, blood to the tissue of the heart.

No blood supply due to obstruction occlusion ischemia hypoxia cell death

Ectopic focus ventricular fibrillation


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NervousSystem

Integration and control of all body functions

Stroke: Bleeding of blood vessels resulting in partial paralysis

Blood Vessels

Central Nervous System (CNS)

- All the nerve tissue enclosed by the bone

- Brain & spinal cord

Peripheral Nervous System (PNS)

- Nerve tissue that is not enclosed by the bone

- Nerve fibers from the spinal cord, muscle

nerve fibers


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Coagulant fills where theres an explosion

Fibers cross over in brain stem; left side of the brain controls the right side of the body.

Reflex Arch

Frontal executive function

Parietal motor-sensory systems

Temporal auditory

Occipital vision


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There are multiple control systems in the brain

Split brain syndrome (still used to treat epilepsy)

Underneath the frontal lobe emotional control and memory

Cerebrospinal fluid underneath and around the brain

The top and under pressures are the same

The fluid is inside 4 ventricular chambers

Central Nervous System

Autonomic Nervous System

Corpus Callosum

Bridge to share information

Sympathetic Nervous System

Fight Mode!

- Excitatory

Parasympathetic Nervous System

Flight Mode!


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Respiratory(Pulmonary)System

Enables cardiovascular system to exchange gases with air

Nose, pharynx, larynx, trachea, lungs

lunglungairair VPVP =

PairVair is constant Plung decreases; Vlung increases rush of fresh air through the lungs

Huge oxygen gradient between the deoxygenated blood and alveolar

As the red blood cell flows, oxygen is diffused through mucosa (secreted by the certain cells

that have hair) and the red blood cell fills with oxygen. CO2 is formed as HCO3- because it is

not desired in gas phase in the plasma. It is dissolved in acid form. The undissolved part is

carried by the red blood cell.

CO2 is diffused freely in alveolar.


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Smoking: Smoke has tar in it. Tar sits on top of mucosal layer. Alveolar needs to secrete

more mucosa. The thickness has increased, diffusion takes longer. If you smoke more, the

distance that the oxygen should travel increases and theres no more oxygen transfer.

Emphysema

Respiratory system is controlled by signals if cerebellum.

Gastrointestinal(Digestive)System

Concerned with the ingestion and digestion of food, elimination of the residues of the

gastrointestinal system

Liver, gallbladder, pancreas, stomach, intestines colon

Gastroesophageal reflux

1. Neoplasia

2. Dysplasia

Esophagus peristaltic activity

(Squeezes the food down)


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3. Cancerous formation

o Immortality

o Uncontrolled growth

Metastatic

Barnetts Esophagus

UrogenitalSystem

Production, storage, elimination of urine

Reproduction

o Kidneys, bladder, ovaries, prostate

Kidneys: Responsible for maintaining water equilibrium, balance of minerals, and removal of

toxic components from the blood.

Filtration system, continuous blood flow

Input: Blood Output: Blood

Bladder


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Kidneys maintain mineral level (Ca, Mg, Zn, Fe)

Maintain homeostasis (static state of the body)

Kidneys are responsible for maintaining blood pressure.

Too much water pressure in blood vessels

Kidneys send hormones to blood vessels to relax the vessels renin activates angiotensin

Squeezing down the vessels

Dialysis: A filtration system to remove toxins and urea from the blood.

Kidney Stone:

Pancreas: Responsible for secreting hormones to maintain blood glucose level.

Hypoglycemia

Diabetes Mellitus


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MusculoskeletalSystem

Muscles & skeleton

Maintaining balance, movement, keeping warm

Amount of signals determine how many muscles should be recruited to carry the weight.

Signals can be sent as a whole or one by one.


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Force generated by muscles is a function of

Neuronal stimulation from the brain (frequency & intensity)

Amount of blood supply

Available nutrients

Ionic concentration around muscle (Ca2+)

Previous activity level

Lactic acid vs. endurance

Hypertrophy

EndocrineSystem

Regulation and control of visceral functions

Secretes hormones via glands that control growth, metabolism and reproduction.

o Pituitary gland, thyroid, parathyroid, adrenalin gland, thymus

Glands are bags that are covered by muscles.


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Pituitary gland: growth, reproduction

Thyroid gland: around the trachea at the larynx

Controls the rate of metabolism

o Hyperthyroidism

o Hypothyroidism

Parathyroid gland: on top (around) the thyroid gland

Responsible for maintaining calcium balance in the blood stream and tissues

Adrenal glands epinephrine

Small amounts vasodilation

Large amounts vasoconstriction


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HematopoieticSystem&LymphaticSystem

Production of blood & blood components

Immune system components

Bone marrow, spleen, lymphatic tissues

Bone marrow: production of red & white blood cells

Spleen: storage of blood cells

Lymphatic tissues: collection of plasma, dead red blood cells

Production of immune system components

Red blood cells: storage of hemoglobin

White blood cells: soldiers of the body

Integumental System

Skin, hair, nails

Skin protection

Nails finger support

Hair protects the brain from heating, provides sweating

HW 2

PART I: Pick a physiological system of your choice and describe its functions, organs in 2

pages

PART II: Find a major disease of this system. Explain its pathophysiology, progression,

diagnosis and therapeutic interventions in 1 page.


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BIOMEDICALDEVICESSensors that are used to measure electrical, chemical, physical activities from human body

Invasive

Ionization (radiation) X-ray, UV, -ray

Contact with blood

Intrusion into the body

Minimally invasive

Contact with blood

Intrusion into the body

Non-invasive

Surface or remote diagnosis / therapy

Biomedical Instruments

Diagnostic Therapeutic

Invasiveness

Non-invasive Minimally

invasive

Invasive


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A General Block Diagram for a Diagnostic Instrument

CPU

DisplayInstrument

Control

Data

Acquisition

Sensors

Memory

Printer

Rem

ote


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BIOMEDICALSENSORS

ChemicalSensors

Blood components, glucose, ions, hormones, and pH, O2, CO2

ClarkElectrode

Rate of electron transfer is measured by the resistance of electrodes.

A

LR

sLawOhmIRV

=

= '

+

+

++

+

+

AgClClAg

eAgAg

OHeOHO 4422

O2 measurement

Clark Electrode

- Invasive (accurate)

- Non-invasive not so accurate

Pulse Oximetry

- Non-invasive (not so accurate)


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PulseOximetry

Hb

HbO2

Finger

Detector: non-laser red light sources

Light is used to measure the concentrations of [HbO2] and [Hb]

(Near infrared)

( )( )

=

2

1

2

OD

ODBAOS

S O2: Saturation of O2

OD: Optical Density

BiochemicalSensors

Glucose, hormone, blood components

O2 measurement: spirometer to measure O2 gas amount and CO2 gas in the air

exchanged by the lungs

ElectricalMeasurements

Results of biopotentials biologically generated electrical signals

Cells are electrically excitable.

Detector

1 2


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Resting membrane potential

Due to the existence of ions across the cell

membrane

Action Potential

Is due to the rapid exchange of ions across cell membrane through channels and gates

Muscle cell gates

Heart muscle gap junctions transfer electrical potentials between cells

Dipole

Einthovens triangle

Electrical Sensors

Non-invasive

Surface type Surface electrodes

Invasive

Needle deep tissue measurement


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Electrolyte: electrically conductive gel with NaCl

It allows the passage of electrical signals to the metal

Adhesive secures the electrode onto the skin surface.

Electrocardiogram(ECG)P: atrial contraction

QRS: left ventricle contraction

T: refilling of the ventricle

Heart Rate

Pacemaker

Skin

Electrolyte

Wire

Double side adhesive

Ag / AgCl


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Electromyogram(EMG)

Measurement of electrical signals of the muscle

Needle electrodes

200-400 m thick wires

Invasive

Electroencephalogram(EEG)

The electrodes make a goof approximation about the electrical

activity.

20 electrodes across the head (cap electrodes)

Cable of electricity

Stimulus

+

_

_

+


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Visual Evoked Potential

Evoked Response

Cortical electrodes

HW 3

PART I: What are the operational principles and clinical applications of

1. ECG

2. EMG

3. EEG (1 page each)

PART II: What is functional electrical stimulation (FES)? What are its clinical applications?

(1 page)


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PhysicalMeasurements

Volume, force, temperature, pressure, sound

VolumeMeasurement

To measure the change in current:

A

LR

I

VR

=

=

Calibration curve

A

+

Rubber strand

Breath

lR

R

Linear sensitivity


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Transducer

Breathing by rubber strand:

Force&StrainMeasurement

I II III

I limit of detection

II linear range

III saturation (cut-off) range

V

T

periodmin

breathsofnoRateBreath =

12-15 min-

- Amplitude gives basic info about

the amount of air exchange

A

+

V

I

l Rubber

substrate

l

F


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lRF

1. Intraesophageal balloon

2. Strain Gage

Pump

Rubber

Needle Surface of stomach


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PiezoelectricTransducer

o Force, pressure, flow

A crystal that produces electricity when mechanically strained.

Q: electric charge produced F: force applied

k: coefficient of the crystal

BloodPressureMeasurement

Metal

VoltmeterF F

kFQ =


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TemperatureMeasurement

1. Mercury Based Measurement

2. Electrical Thermometer

3. Optical Thermometer

Electrical Thermometer

R(T) = R0 exp 1

T

1

T0

"

#$

%

&'

(

)*

+

,-

IR1

T

Biosensors

Sensors that measure the concentration of chemical components of solution

+

IThermistor

Cholesterol

Glucose

Membrane

Biological

compound

TransducerEnzyme


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Glucose + enzyme glucanic acid alters the pH of the sheet

pH Glucose

HW 4

PART I: What is a biosensor? Find 1 clinical application for it.

PART II: What is a molecular beacon? What is a quantum dot? Find their usage in biology.


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BIOMEDICALINSTRUMENTATION

A generalized block diagram of a biomedical device

DataProcessingUnit

Noise Removal

Elimination of unwanted signals

Electromagnetic interference

= Power lines, TV-Radio broadcast, mobile phones, computers, lab equipment


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1. Noise filter

Transfer function filter out unwanted noise

2. Data Filter

Designed to extract relevant physiological information out of others

Low pass filter, high pass filter, band pass filter

Convolution: y(t) = x(t) * hD(t)

3. Gain

Performed to increase the amplitude of the signal

h (t) y (t)x (t)

Transfer Function

hD (t) y (t)x (t)

x (t) G y (t) = G x (t)


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4. Differential Measurement

)()()(

)()()(

)()()(

21

2

1

tVtVVVtV

tntVtV

tntVtV

LRo

L

R

==

+=

+=

To eliminate common noise

Typical signal conditional steps

V1(t)

V2(t)

VR(t)VL(t)

n t

+

_Vo t

Differential

measure

Noise

filter

Data

filterGain

G y (t)+

_hN (t) hD (t)

[ ])()(21

txtx [ ] )()()(21

thtxtxN

[ ]{ } )()()()(21

ththtxtxDN

[ ]{ } )()()()()( 21 ththtxtxGty DN =

Sensor SCU CPU

CPU = MicroprocessorA/D converter +


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Analog to Digital Convertors

Types of Signals

1. Analog real world, continuous signal

2. Digital digitized signals sampled and stored in the computer

o A digital representation of the signal

A / D Converter

Resolutions

1. Temporary Resolution

o How fast a signal is sampled [samples/sec] = sampling rate Fs

Typically Fs = 1000 samples/sec

2. Dynamic Resolution

o How fine are you quantizing a signal? [bits]

nVV

levelsofnoRangeDynamic

2

minmax

==

n: number of bits = 10-12 bits

Ex: 12 bit A / D converter, Fs = 200 samples/sec records data for 10 min from 16 electrodes.

What is the size of the data file?

( ) MBytesbitsM

sensorsofnorecordofDurationFbitsofnosizeData s

8.22316601020012 ==

=


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BiomedicalSignalProcessing

Bioelectric Signals

Generated by nerve and muscle tissues when they are electrically active.

Result of electrochemical changes across the cell membrane.

Biomagnetic Signals

Magnetic fields are generated due to changes in electric field.

Magnetoencephalogram (MEG)

Biochemical Signals

Concentrations of ions (Ca2+, K+, Na+, Cl-), hormones, chemical compounds, blood

gases

Biomechanical Signals

Motion, displacement, tension, force, pressure, flow

Bioacoustics Signals

Due to vibration, flow of blood, respiratory system (lung) sounds


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Deterministic: an explicit mathematical representation exists

Periodic signals )()( Ttxtx +=

Aperiodic signals TtAetx/)( =

Characteristics of Signals

Deterministic Signals

Periodic Aperiodic

Random (stochastic) Signals

x(t)

t

T

A -

Tte

/

t

x(t)


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Random: characterized by statistical values (mean, standard deviation)

EEG signals

FourierTransform

A means of representing the contribution (weight) of different frequencies within a signal

1. )sin()( 111 tAtx =

2. )sin()( 222 tAtx =

A1

- A1

T1

A2

-A2

T2

xT(t)


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Fourier Transform is random.

EEG

o Grand averaging Ensemble averaging

A1

A2

x(f)

frequencyf1 f2

Data Compression


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MEDICALIMAGING

QualityinMedicalImaging

1. Spatial Resolution

How small can we detect [pixels/area]

2. Contrast Resolution

How fine of colors do we see? [bits/pixel]

3. Temporal Resolution

How many images can you take in 1 second?

[frame rate] = [frames / second] 24 frames/sec (real time)

Functionality

Morphological

Anatomical

Map of organs

Physiological

Provide information

on how well an organ

is functioning

Invasiveness

Non-invasive

Remote

Surface contact

Min-invasive

Intrusion into the

body

Contact w/ blood

Invasive

Radiation

Medical Imaging


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RadiationImaging

- Depends on the use of X-rays to image the absorption (attenuation) distribution of the

tissues

I < I0

1896 Discovery of X-ray

1901 The very first Nobel Prize was given to Wilhelm Conrad Roentgen

Object

I0

I

Photographic filmcovered withfluorescent material

Source

Object

Fluorescent material

Visible light


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PrinciplesofX-RayImaging

Attenuation of X-rays by tissues between body parts having minimally different density, fat,

muscle, result in a shadow image

Collimator: aligns X-ray beam

e-

X-ray lamp

Pulse

generation

Collimator

Florescent

cover

Photographic

film

A grid of photo

detector

Holes

Pb


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PhysicsofX-RayImaging

hfE=

h: Plancks constant

f: frequency of electromagnetic wave

=

cf

Ionization: decomposition of matter

- Vaporization of tissues

rays, X rays pass through tissues and give permanent damage to skin

Ionizing radiation

z

I0

DetectorX-ray source


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mzeIzI

= 0)(

z: distance between source and detector

: density of the object

: attenuation coefficient

UnitsofX-rayExposure

Roentgen R = 2.58 * 10-14 C/kg

- Produces ionization of either charge (+ or -)

When light enters (I0), some of it is absorbed by the body not to eliminate X-ray

immediately.

A typical X-ray session: 10 100 millirads

- Absorption of X-ray by body (chest X-ray)

Onset of radiative effect: 50 rads

Radiation death > 200 rads

GeometricUnsharpness

X-ray

source

Fan beam

f

Image plane

s

t


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s: source to image plane distance

t: center of object to image plane distance

f: fixed size of the object

ts

tfd

=

Goal: minimize d (f fixed)

1. Increase s increase source detector distance

2. Decrease t bring the object close to image plane

X-rays planar image

ComputerAidedTomographyScanner(CATScan)

- Computerized Tomography (CT)

The detector rotates and cross-section images are obtained at every 1-2o

Source

Detector


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iii =

We have 4 unknowns

We need 4 independent projections to solve s Back Projection Algorithm

- Reconstruct cross-sectional image of an object by projected data

1st

Generation CT

1 source, 1 detector

60 seconds to 4-5 minutes for each rotation

Rotates at every 6o angle for one cross-section

2nd Generation CT

1 source 30 detectors

All detectors are close to the source at equal distances to reduce geometrical sharpness

3rd

Generation CT

300 detectors 2 4 seconds

11 1

22 2

33 3

44 4

1+ 3

1+ 2

1+ 4

2+ 4


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4th

Generation CT

Only the source (fan beam) is rotating

700 detectors around (2 4 seconds)

Fluoroscopy

Patient is given a radio opaque (X-ray absorber) material and the movement of this material

is observed under light by camera.

Angiography

Injection of radio opaque material into the veins for observation of occlusions

HW 5

1. What is X-ray mammography?

2. What is balloon angioplasty?


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RadionuclideImaging

Nuclear medicine radioactive elements

Invasive ionizing radiation

Functional physiological imaging Curries

Nuclear particles

energyenp

energyepn

e

e

+++

+++

++

+

The solution circulates in the body and targets several organs

I radioisotope mixed in the solution and accumulates in thyroid

C6H12O6 Isotopes C11, C15 accumulates in the parts where glucose is consumed

e-

n, p+

energy

Powder

radioactive mix in

solution

Through a

catheter


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PositronEmissionTomography(PETScan)

An imaging technique that uses cameras ( cameras) to monitor the whereabouts and

intensity of a radioactive element injected into the body

It is possible to monitor the progress of the activity in

time.

It can be used to measure the effect of chemotherapy.

It can also be used to measure the effect of the drugs.

RadioactiveDecay

teNtN

= 0)(

N0: initial amount of material

: decay constant

t: time

693.02/1=T


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BiologicalHalf-lifeTime needed for the body to excrete half of the amount of radionuclide. Tb1/2

b

beff

TT

TTT

2/12/1

2/12/1

2/1

+

=

O15, T1/2 = 122 sec

C11, T1/2 = 20.5 min

Molecular Beacon

Quantum Dot


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MagneticResonanceImaging(MRI)

- Uses non-ionizing radiation to probe the soft tissue contrast

- Provides excellent soft tissue contrast

PhysicsofMRI

Uses electromagnetic waves at radiofrequency (50-60 MHz)

Charged electron spinning around the axis

- Creation of 2 poles

- Magnetic dipole moment

Magnet

1. All spinning nuclei have a characteristic resonance frequency which depends on the

atomic composition

2. When atoms are combined to form larger molecules, their overall resonance frequency

depends on their total weight

Non-magnetic

- Because all moments facing different directions

S N

All moments are at the same

direction


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NuclearMagneticResistanceSpectroscopy(NMRS)

LarmorFrequency

f

2

0

=

=

: gyromagnetic ratio

0: applied magnetic field

Each molecule starts to rotate according to gyromagnetic ratio, resulting in A, B, C, and

D.

DCBAT

T

A

IIIII

I

IA

+++=

100%

Different proportion of molecules

Different spinning frequency


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PG Re

B1

B0

S N

1. Place the sample inside a static magnetic field (B0)

2. Close S1 (off S2)

Generate a B1B0, B1


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ImagingInMR

Idea: Image 3-D object according to the distribution of H+ ion

Each cube is called a voxel.

Min resolution: 1 mm x 1 mm x 1 mm

=

+

+

TT

H

B

H

Rec PC

PGX

S

PGY

PGZ

Srec

Display

SX SY

SZ

N


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PG require high current to operate

High current means heat generation cooling system is necessary

MRI

- An anatomical imaging technique

- Used in observing tissue contrast changes

(Inflammations, lesions, tumor formation, muscle injury)

- Contrast agents enhances MR signal to investigate joints (Gd injection)

Functional MRI (fMRI)

- Used only for research

- Measurement of physiological changes in human body

(Manic depressive normal brain)

It uses hemoglobin molecule to trace the functional activity level of the brain.

HW 6

PART I: What is CT-PET Scanner? What is its clinical use?

PART II: What are functional MRI and its clinical use?


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ULTRASOUNDIMAGING

Uses sound waves to probe the mechanical properties of the tissues (pressure waves)

= 1500 m/sec

Some sound waves reflect from the boundary. Some continue their way.

ultra not audible 5 30 MHz

ffz

fat ePzP

= 0)(

P0: initial intensity of pressure wave

!: attenuation coefficient of the tissue

! = !f f: frequency of operation

!: initial coefficient

zf: thickness of the tissue

f Pf (more attenuation) less penetration depth but spatial resolution increases


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Medical Ultrasound

Amplitude (A mode) Ultrasound

Diagnostic Therapeutic

- Kidney stones (lithotripsy)

- Wound healing

- Bone healing

- Muscle injury rehab

- Surgical

Anatomical Functional

Blood flow


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Brightness Mode (B Mode)

Array of US sensors

The echoes are turned into gray scale image

Non-invasive!


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DopplerUltrasound

Doppler Effect is the result of changing the wavelength of a source by its velocity.

0

cos2f

Cf

d

=

: velocity of object

C: speed of sound

P1 (fd)

P0

US Beam

f0

OcclusionFront (coronal) view

f0

fd

: measure the change in blood velocity


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Kidney Imaging

Echocardiogram

B mode: observe anatomical problems

Doppler: quantify the degree of disease

Doppler is less invasive than B mode because the patient is exposed to less Ultrasound.

(Still the two applications are non-invasive)

Blood moving away

from the probe

Blood towards

the probe

Kidney stone

B Mode + Doppler US

Live anatomical image of the heart

+ Movement of blood through the heart


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TherapeuticUltrasound

Lithotripsy (stone breaking)

Locating the Stone

Bathtub

Ultrasound (transmitter)


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ElectroShockWaveLithotripsy

BiomedicalOptics

The use of light in diagnostic and therapeutic applications

Diagnostic

Microscopic

(100m)

Therapeutic

Surgical Rehab Cosmetic


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Light and Matter Interaction

Depends on the

1. Wavelength

2. Intensity

VisibleLightImaging

- Endoscopy

- Coils to move the tubes to look around the organs

- 4 holes, 5 mm in dimension

FluorescenceImaging

- A certain color of light is used to excite certain chromophores

Absorption Scattering

ray X ray UV vis Infrared

Non-invasive

(Diagnostic)

High water

absorption

Invasive

(Treat cancer)

Less water

absorption


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Therapy

Surgical inventions

o Cut the tissues

o Coagulate the vessels and tissues

o Ablate the vessels and tissues

o Weld the tissues

Laser

Coherent, focused light beam

RehabilitationProceduresofLight

Infrared Therapy

o Tissue Damage

Cosmetic applications

1. Plastic Surgery

2. Epilation

Pupil

Cornea


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Comparative Matrix of Imaging Systems1

Ionization Operation Clinical Use Resolution

(mm)

Real

time

Cost* Mobility Invasiveness

X-RayVery low Anatomic

Soft/hard tissuecontrast

3-5 mm No Low Yes 4

CT Low Anatomic Soft tissue 1-2 mm No High No 5

USNone

Anatomic/Functional

Soft tissue 2-3 mm Yes Moderate Yes 1

MRI None Anatomic Soft tissue 1-2 mm No High No 3

PET High Functional Metabolic 3-5 mm No High No 6

Endoscopy None Anatomic Surface 1 mm Yes Low Yes 2

* Low < $50K, Moderate $50K - $200-300K, High > $300K

1:Most non-invasive, 6: most invasive

1 I would like to thank Mrs. Nilfer Adoran from the MDSI (2012) program for helping me

with this table


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RehabilitationEngineering

Application of technology to help (ease) the problems faced by people with disabilities

Activities in Rehabilitation Engineering

1. Prosthetics and Orthotics

Artificial hand, wrist, arms, foot, legs,

Hand splits, upper limb braces

Bone / joint prosthetics

- Functional

- Biocompatible

2. Assistive Devices for persons with severe visual impairments

- Devices to aid reading, writing

TV magnifiers, electronic Braille

- Aids for independent mobility (laser cane)

3. Assistive Devices for persons with severe auditory impairments

- Digital hearing aids cochlear implant

Cochlea

Mic

Skull


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- Lip reading instruments

4. Mobility manipulation aids

- Grabbers, feeders, page turners, wheel chairs, driving aids

A general block diagram of an assistive technology

Sensors

Perception Cognition Motor Control Effectors

Analog data

Digitalized

datainformation knowledge


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ClinicalEngineering- An engineer who manages, maintains and improves the safe use of medical equipment in

hospitals

- It started when safety problems aroused

Electroshock, electrocution proper grounding issue

Job Descriptions of Clinical Engineers

Supervise performance of safety testing of medical equipment by companies

Repair medical instruments

Inspect of incoming equipment

Organize inventory control

Manage calibration and repair services

Coordinate outside use of technical services

Train medical personnel in safe and effective use of equipment

Develop and implement documentation protocols required by external accreditation

and licensing agencies

Safety Issues in Hospitals

Dangers: - Electrical Hazards

- Mechanical Hazards

- Environmental Hazards (solid, waste, noise, utilities, gas)


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- Biological Hazards: infection control (isolation, contamination, sterilization,

biological waste disposal)

- Radiation Hazards

MedicalEthicsNature of Life and Its Significance

Immanuel Kant (1724 1804)

- What can I know?

- What I ought to do?

- What can I hope?

- What is man?

Ethics

- Represents the codes of conduct of society, the study of right and wrong, good and evil in

human conduct

Questions

1. Should body deformed infants kept alive?

2. Should treatment be stopped to allow terminally ill patients to die?

3. Should humans be used in experiments?

Medical Dilemmas

1. Is it more important to preserve life or prevent pain?

2. Is it right to withhold treatment when doing so may lead to a shortening of life?


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3. Does an individual have the right to refuse treatment when refusing it may lead to

death? (Euthanasia: good death)

Kants theory: Humans are owed a special kind of respect simply because they are people

Experiments

Human Ethics Review Board Animal Ethics Review Board


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