各種生体信号 - university of aizuweb-ext.u-aizu.ac.jp/course/bmclass/documents/bio-2-1.pdf–...
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バイオメディカル情報工学 第二部 生体情報技術入門
第一章 生体信号の基礎 1
第2部 生体情報技術入門第2部 生体情報技術入門
第1章 生体信号の基礎
生体情報学講座生体情報学講座教授教授 陳陳 文西文西
各種生体信号各種生体信号Biosignal Range Freq.,
HzSensor
心弾動図Ballistocardiogram (BCG)
0-7 mg 0-40 Accelerometer, strain gage
0-100 μm
0-40 Displacement (LVDT, Linear Variable Differential Transformer )
膀胱圧 1-100 0-10 Strain gage manometer膀胱圧Bladder pressure
1 100 cm H2O
0 10 Strain gage manometer
血流Blood flow
1-300 ml/s
0-20 Flowmeter (electromagnetic or ultrasonic)
動脈血圧Blood pressure, arterial
直接 10-400 mm Hg
0-50 Strain-gage manometer
間接 25-400 mm Hg
0-60 Cuff, auscultation
静脈血圧Blood pressure, venous
0-50 mm Hg
0-50 Strain gage
Biosignal Range Freq., Hz Sensor
血液ガスBlood gases
PO2 30-100 mm Hg
0-2
Specific electrode, volumetric or manometric
PCO2 40-100 mm Hg
0-2
PN2 1-3 mm Hg
0-2
PCO 0 1- 0-2PCO 0.10.4mm Hg
0 2
血液pHBlood pH
6.8-7.8 pH units
0-2 Specific electrode
心拍出量Cardiac output
4-25 liter/min
0-20 Dye dilution, Fick
心電図(ECG)Electrocardiogram
0.5-4 mV 0.01-250 Skin electrodes
脳波(EEG)Electroencephalogram
5-300 μV 0-150 Scalp electrodes
Biosignal Range Freq., Hz Sensor
皮質脳波(ECoG)Electrocorticogram
10-5000 μV 0-150 Brain-surface or depth electrodes
筋電図(EMG)Electromyogram
0.1-5 mV 0-10,000 Needle electrodes
眼電図(EOG)Electrooculogram
50-3500 μV 0-50 Contact electrodes
網膜電図(ERG)Electroretinogram
0-900 μV 0-50 Contact electrodes
電気皮膚反応(GSR) 1-500 kΩ 0 01-1 Skin electrodes電気皮膚反応(GSR)Galvanic skin response
1 500 kΩ 0.01 1 Skin electrodes
胃筋電図(EGG)Electrogastrogram
10-1000 μV 0-1 Skin-surface electrodes
0.5-80 mV 0-1 Stomach-surface electrodes
Gastrointestinal pressure胃腸圧
0-100 cm H2O
0-10 Strain-gage
Gastrointestinal forces胃腸力
1-50 g 0-1 Displacement system, LVDT
胃pHGastric pH
3 - 13 pH units
0-1 pH electrode, antimony electrode
Biosignal Range Freq., Hz
Sensor
神経電位Nerve potentials
0.01- 3 mV 0-10,000
Surface or needle electrodes
心音図Phonocardiogram (PCG)
Dynamic range 80 dB, threshold about 100 μPa
5-2000 Microphone
容積脈波 Plethysmogram(volume change)
Varies with organ
0-30 Displacement chamber or impedance change
呼吸機能Respiratory functions
Flow rate 0-600liter/min
0-40 Pneumotachograph head and differential pressure
Respiratory rate
2-50breaths/min
0.1-10 Strain gage on chest,impedance, nasal thermistor
Tidal volume
50-1000ml/breath
0.1-10 Above methods
体温Body temperature
32-40 90-104
0-0.1 Thermistor, thermocouple
生体内の圧力生体内の圧力臓器系 圧力名 説明
循環器 心室内圧 心臓の収縮と拡張
(大)動脈圧 左心室の収拡によって(大)動脈内の圧力、血圧BP静脈圧 静脈血管内の圧力。右心房近傍の中心静脈圧CVP肺動脈圧 右心室の収拡によって肺動脈内の圧力PCWP
第2部 生体情報技術入門 第1章 生体信号と計測技術
微小血管内圧 直径20-250umの血管内圧、微小循環動態
呼吸器 気道内圧 呼吸に伴って生じる気道内の圧力、呼吸機能
胸腔内圧 呼吸に伴って生じる胸腔内の圧力、呼吸機能
泌尿器消化器
消化管内圧 胃あるいは腸管の内圧
膀胱内圧 膀胱内に貯留する尿液の圧力
尿道内圧 排尿するための圧力
その他 頭蓋内圧 頭蓋骨内部の圧力ICP。脳圧、脳髄液圧とも言う
眼圧 眼球内の圧力
子宮内圧 羊膜内の羊水圧
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バイオメディカル情報工学 第二部 生体情報技術入門
第一章 生体信号の基礎 2
生体内圧の変動範囲生体内圧の変動範囲
第2部 生体情報技術入門 第1章 生体信号と計測技術
各種体温と計測部位各種体温と計測部位
第2部 生体情報技術入門 第1章 生体信号と計測技術
睡眠時体表温度の変動睡眠時体表温度の変動
第2部 生体情報技術入門 第1章 生体信号と計測技術
心電図心電図
心電図と動脈血圧心電図と動脈血圧 心電図と呼吸心電図と呼吸
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バイオメディカル情報工学 第二部 生体情報技術入門
第一章 生体信号の基礎 3
自発脳波自発脳波 誘発脳波誘発脳波
筋電図筋電図
33年間血圧(収縮圧と拡張圧)年間血圧(収縮圧と拡張圧)
33年間脈拍数年間脈拍数信号の多様性信号の多様性
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バイオメディカル情報工学 第二部 生体情報技術入門
第一章 生体信号の基礎 4
生体信号と計測生体信号と計測
• Biosignal– Physical, chemical, mechanical, thermal, electrical
and magnetic quantities that contain information of health condition in physiology and psychophysiology.
• Detection– Transduction - a procedure by which the quantity
that characterizes the property or state of an object was sensed or transduced.
– Conditioning analogically and digitally - a procedure of obtaining wanted information or signal components from the above object quantity.
計測手法計測手法
計測システムの基本構成計測システムの基本構成 生体計測の特殊性生体計測の特殊性
• 組織・器官破壊や生理状態の乱れを最小限にする
• 生理量の変化は短時間の成分にも長時間の成分にも意味があり、計測システムの広い周波数応答性と高い生物的 化学的安定性が要求される性と高い生物的・化学的安定性が要求される
• 組織や器官が柔らかく壊れやすく、異物に対して拒絶反応のため、生体と直接接触するセンサ素材に生物親和性が要求される
• 人間に意思と感情があり、強制や拘束、不快や痛みを最小限にする
システムパフォーマンスシステムパフォーマンス
• 静的特性
– The performance of instruments for DC orvery low frequency inputs.
– Some sensors, such as piezoelectricdevices, respond only to time-varyinginputs and have no static characteristics.
• 動的特性
– The performance of instruments for atransient or higher frequency inputs.
– Differential and/or integral equations areused.
静的特性静的特性 -- 11• Accuracy
– The difference between the true value and themeasured value divided by the true value(reference)
• Precision– The number of distinguishable alternatives from
which a given result is selectedl• Resolution
– The least value of the object quantity that can bedistinguished at the output of the measurementsystem
• Reproducibility or repeatability– The ability to give the same output for equal inputs
over time• Sensitivity
– The ratio of the incremental output quantity to theincremental input quantity
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バイオメディカル情報工学 第二部 生体情報技術入門
第一章 生体信号の基礎 5
静的特性静的特性 -- 22• Linearity
– Response property of outputs to addition andmultiplication of inputs
• Range– Minimal resolvable inputs – a lower bound on the
quantity to be measuredM t th i l ll bl h f– Measurement range – the maximal allowable change ofthe object quantity that give the nominal performance
• Input impedance– The ratio of the phasor equivalent of a steady-state
sinusoidal effort input variable (voltage, force,pressure) to the phasor equivalent of a steady-statesinusoidal flow input variable (current, velocity, flow)
• Hysteresis– The input-output relation depends on the direction and
the range of successive input values
感度感度
感度のドリフト感度のドリフト 線形性線形性
入力インピーダンス入力インピーダンス
• The degree to which instruments disturb thequantity being measured smaller=better
• Xd1 – desired input quantity we seek to measure• Xd2 – implicit input quantity to be required by
instrumentsinstruments• Generalized input impedance Zx larger=better
• Power P=Xd1*Xd2 smaller=better– instantaneous rate at which energy is transferred
across the tissue-sensor interface
variableflow
variableeffort
X
XZ
d
dx _
_
2
1
ヒステリシスヒステリシス
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バイオメディカル情報工学 第二部 生体情報技術入門
第一章 生体信号の基礎 6
動的特性動的特性
• Transfer functions– 0th order, 1st order, 2nd order
• Linear and nonlinear systems– Linear system – the response to simultaneous
inputs is the sum of their independent inputsinputs is the sum of their independent inputs– Nonlinear system – higher harmonics appear but
close to linear system in small range• Frequency response
– The distribution of the amplitude and the phaseshift of the output to sinusoidal inputs of unitamplitude over the whole frequency range
• Time parameters– Time constant, response time, rise time, settling
time, time delay
伝達関数伝達関数
txbdt
tdxb
dt
txdbtya
dt
tdya
dt
tyda
m
m
mn
n
n 0101 ......
L l f
Differential equation
Laplace transform 01
01
...
...
asasa
bsbsb
sX
sYn
n
mm
01
01
...
...
ajaja
bjbjb
jX
jYn
n
mm
js When
零次システム零次システム
txtya 0K
a
0
1Static sensitivityDifferential
equation
Zero phase shift
Constant
Output
Input
一次システム一次システム
txtyatdy
a 01
Ka
0
1Differential equation
Static sensitivity
txtyadt
a 01
teKty 1
Step response
0
1
a
a
Time constant
1
Cutoff frequency
二次システム二次システム
txtyadt
tdya
dt
tyda 012
2
2
KaKS
0
11
Static sensitivity
Differential equation
Undamped natural frequency
Damping ratio
2
0
a
an
20
1
2 aa
a
>1 Overdamped=1 Critically damped<1 Underdamped
時間域パラメータ時間域パラメータ
• Time constant– 1st order system, time to 63.2% of the final value in
step response• Response time
– time to 95% of the final value• Rise time• Rise time
– 2nd order system, time interval from 10% to 90% ofthe final value
• Settling time– 2nd order system, time to settle within a definite
range, ex. ±5%, near the final value• Time delay
– time to output after input is applied– phase angle varies with frequency – the delay is not
constant in frequency domain
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バイオメディカル情報工学 第二部 生体情報技術入門
第一章 生体信号の基礎 7
一次システム一次システム二次システム二次システム
振幅とパワー振幅とパワー
• Peak-to-peak value– Difference between the maximal peak and the
minimal valley
Root Mean Square (RMS) amplitude
))(min())(max( txtx
• Root-Mean-Square (RMS) amplitude – Root of average squared signal over time
• Power– Average squared signal over time
2)(tx
2)(tx
パワースペクトラムパワースペクトラム
• Distribution of signal power over frequency• Fourier series of any periodic function of time
Tot l po e
1
00 sincostn
nn tnBtnAx T
20 where
• Total power
• Fourier transform of any function of time
• Total power
1
222
2
1t
nnn BAx
dXx2
0
2
2
1t
dtetxX tj
信号とノイズ信号とノイズ
• Signal– the component of a variable that contains
information about the object quantity• Noise
– a component unrelated to the object quantity
• Signal ↔ Noise– not defined by physical nature but by the intention of
the observer• Signal-to-Noise Ratio (SNR)
– P and A indicate power and RMS amplitude, respectively
N
S
N
S
A
A
P
PSNR 1010 log20log10dB
ノイズの種類ノイズの種類
• Thermal Noise– Random thermal agitation relevant to temperature– Uniform distribution of power density
• 1/f Noise– Many natural phenomenaMany natural phenomena– Power density is inversely proportional to the
frequency• Interference
– Electromagnetic coupling - power line, fluorescentlamps
• Artifact– Superimposed on the object quantity and caused by
external factors such as motion – skin-electrodecontact
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バイオメディカル情報工学 第二部 生体情報技術入門
第一章 生体信号の基礎 8
ノイズの確率分布ノイズの確率分布amplitude amplitude
probability
uniform distribution
time
amplitude
amplitude
amplitude
amplitude
probability
probabilitydensity function
Gaussian distribution
timeprobability of noise occurs in such amplitude
絶対値計測絶対値計測
• Standard– Intrinsic standards such as mercury column and gravity of
the earth for pressure, ice point of pure water and melting point of gallium for temperature
– Reliable instruments such as crystal-resonator temperature sensors for body temperature thermometertemperature sensors for body temperature thermometer
• Calibration– Nonlinear system – many points– Linear system – two points– Curve fitting in the sense of least squared errors between
input and output• Accuracy
– How close the measured value is to the true value• Error
– Difference between the measured value and the true value
誤差の種類誤差の種類• Random error
– Appears unpredictably in repeated measurements– Averaging is an effective way to reduce random errors
• Systematic error– The bias from the true value appearing equally in
repeated measurements of the same object quantity– Origins – drift, improper calibration, uncorrectedg
nonlinearity, round down in digital data• Dynamic error
– Occurring from imperfect dynamic characteristicswhen the object quantity varies so quickly that theoutput of the measurement system does not followthe change of the input
• Quantization error– The difference between the original analog value and
the converted digital value during conversion of ananalog value to a digital value
量子化誤差量子化誤差
演習課題
心臓電気活動の計測心臓電気活動の計測
演習課題
イオン交換と動作電位イオン交換と動作電位
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バイオメディカル情報工学 第二部 生体情報技術入門
第一章 生体信号の基礎 9
動作電位と心臓電気伝導動作電位と心臓電気伝導 異なる視点からの観測異なる視点からの観測
電極位置と信号パターン電極位置と信号パターン 心電誘導と心電図心電誘導と心電図
標準標準1212誘導心電図誘導心電図
双極肢誘導(標準肢誘導)
単極肢誘導
単極胸部誘導
心電図心電図パラメータパラメータ
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バイオメディカル情報工学 第二部 生体情報技術入門
第一章 生体信号の基礎 10
QRS peakQRS peak→→RR intervalRR interval→→HRHR アルゴリズムによる自動検出結果アルゴリズムによる自動検出結果True Positive False Positive False Negative
検出アルゴリズムの性能評価検出アルゴリズムの性能評価• True Positive = correct estimation : Actual TRUE condition
is correctly estimated as TRUE • False Positive = incorrect estimation : Actual FALSE
condition is incorrectly estimated as TRUE• False Negative = incorrect estimation : Actual TRUE
condition is incorrectly estimated as FALSEcondition is incorrectly estimated as FALSE• Sensitivity = ability to estimate correctly in actual TRUE
condition • Positive Predictability = confidence of positive estimation• Accuracy = ability to estimate correctly in actual BOTH
conditions • Specificity = ability to estimate correctly in actual FALSE
condition
性能評価指標の計算式性能評価指標の計算式
SamplesTRUEActualofNumber
PositiveTrue
____
_ySensitivit
PositiveTrue _lityPredictabiPositive
PositiveFalsePositiveTrue __y
SamplesAllofNumber
NegativeTruePositiveTrue
___
__Accuracy
samplesFALSEActualofNumber
NegativeTrue
____
_ySpecificit
課題内容課題内容
• 安静時と運動中、回復中の心電図を計測し、データをメモリカードに記録する
• 一人10分ずつ心電図を計測する(安静3分、運動中3分、回復中4分)
• 運動負荷は各自の体力に応じて個人別に設定する
(HRmax=220-年齢)
運動負荷は各自の体力に応じて個人別に設定する
• 使用設備– 12誘導心電計+負荷自転車又はトレッドミル
• データ処理– QRSピークを特定
– 心拍数プロフィルのグラフを作成
– TP, FP, FNをカウント
– SensitivityとPositive Predictabilityを計算
– 性能改善とリアルタイム処理