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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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