医学影像系统原理7 超声
合集下载
相关主题
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
They also invented A-mode trans-vaginal and trans-rectal scanning transducers in 1955.
15
History of the Development of Ultrasound (IV)
The “Pan scanner” developed in 1957 by Douglass Howry at the University of Colorado, USA. Problem: Immerse totally or partially in water
6
Principle of Ultrasound Imaging
7
Principle of Ultrasound Imaging
A pulse is propagated and its reflection is received, both by the transducer. Key assumption: - Sound waves have a nearly constant velocity of ~1500 m/s in H2O. - Sound wave velocity in H2O is similar to that in soft tissue. Thus, echo time maps to depth.
12
History of the Development of Ultrasound (I)
Karl Theodore Dussik, a neurologist/ psychiatrist from The University of Vienna, Austria was regarded as the first physician to have employed ultrasound in medical diagnosis: locate brain tumor and the cerebral ventricles by measuring the transmission of ultrasound beam through the skull in 1942. The earliest use of ultrasound is in therapy instead of diagnosis:
5
What is ULTRASOUND?
Ultrasound is any sound with a frequency above the range of human hearing, approximately 20 KHz. The most often used frquency band in medical imaging is between 2 and 10 MHz. Sound speed formula: C f Suppose C to be 1540 m/s, the wavelengths in soft tissue are in the range of 0.77-0.154 mm. The high frequencies mean shorter wavelengths.
19
2D Ultrasound Imaging
B-model ultrasound To use the brightness of the screen to display the amplitude of the signal. The greater the amplitude, the greater the brightness of the spot.
14
History of the Development of Ultrasound (III)
After the Korean war, John Julian Wild and John Reid built a linear hand-held B-mode instrument and become the first publication on intensity-modulated cross-section ultrasound imaging.
8
Ultrasound Principle
9
Ultrasound Image (Embryo)
10
Ultrasound: Resolution and Transmission Frequency
Tradeoff between resolution and attenuation -
↑higher frequency ↓shorter wavelength
2
What is SOUND?
来自百度文库
Sound is a mechanical wave that we can hear A mechanical wave can be described by:
Amplitude: a Wavelength: Frequency: f Sound speed: C
Destroy the basal ganglia in patients with Parkinsonism (William Fry, Russell Meyers) Treatment of patients with rheumatic arthritis (Jerome Gersten, 1953)
16
History of the Development of Ultrasound (V)
In 1962, the first commercially available , handheld articulated arm compound contact scanner was produced by engineers William Wright and Edward Meyerdink in USA. The work of Howry and his team is the most important pioneering work in B-mode ultrasound imaging and contact scanning that we have today.
Aluminium 6400 Bone 3500 Liver 1570 Kidney 1560 Blood 1570 Fat 1460 Water 1493 Lung 650 Air 332
4
Properties of Sound Propagation
Sound at different frequency can be transmitted in the same medium at the same speed. The different medium has different speed for sound transmission with the same frequency.
1 C f T
a
3
Sound Propagation Speed
Sound can be transmitted through any mediumgas, liquid, or solid. Sound speed through the medium depends on the compressibility of the medium. The speeds of some materials are shown in the table below. Sound speed in different materials (m/s)
Ultrasound Imaging and Its Applications
Mingyue Ding
Department of Bio-medical Engineering “Image Processing and Intelligent control” Key Laboratory of Education Ministry 2015-7-1
OUTLINES
1. What is ultrasound? 2. History of the development of ultrasound imaging technique 3. 2D ultrasound imaging 4. 3D ultrasound imaging 5. 3D ultrasound imaging applications
11
Frequency Used in US Imaging
To have enough resolution for the observation of human organs, a frequency higher than 0.15 MHz , a wavelength less than 1.0cm, has to be used. Also the frequency will determine the depth of imaging, the lower the frequency, the big the depth will be.
17
Pulse-echo Ranging
D
T C 2
Applications: Bats Sonar system Detects submarines SONAR-Sound Navigation And Ranging.
18
2D Ultrasound Imaging
A-mode ultrasound Horizontal axis is used to represent time while the vertical axis of the signal is to represent the amplitude of the signal.
For abdominal imaging, a frequency between 1.03.0MHz has to be used. For eye examination, a frequency as high as 20 MHz is used. For IVUS imaging, 40 MHz is used.
↑ higher attenuation
Power loss:
dB 1 cm MHz
Typical Ultrasound Frequencies: Deep Body 1.5 to 3.0 MHz Superficial Structures 5.0 to 10.0 MHz e.g. 15 cm depth, 2 MHz, 60 dB round trip Why not use a very strong pulse? Ultrasound at high energy can be used to ablate (kill) tissue. Cavitation (bubble formation) Temperature increase is limited to 1ºC for safety.
13
History of the Development of Ultrasound (II)
Systematic investigations into using ultrasound as a diagnostic tool was made by George Ludwig, a physician at the Naval Research Institute in Bethseda, Maryland in the experiments on animal tissues using pulse-echo ultrasound. “SONICS-techniques for the use of sound and ultrasound in engineering and science” (Theodore Hueter, Richard Bolt) book published in 1954.
15
History of the Development of Ultrasound (IV)
The “Pan scanner” developed in 1957 by Douglass Howry at the University of Colorado, USA. Problem: Immerse totally or partially in water
6
Principle of Ultrasound Imaging
7
Principle of Ultrasound Imaging
A pulse is propagated and its reflection is received, both by the transducer. Key assumption: - Sound waves have a nearly constant velocity of ~1500 m/s in H2O. - Sound wave velocity in H2O is similar to that in soft tissue. Thus, echo time maps to depth.
12
History of the Development of Ultrasound (I)
Karl Theodore Dussik, a neurologist/ psychiatrist from The University of Vienna, Austria was regarded as the first physician to have employed ultrasound in medical diagnosis: locate brain tumor and the cerebral ventricles by measuring the transmission of ultrasound beam through the skull in 1942. The earliest use of ultrasound is in therapy instead of diagnosis:
5
What is ULTRASOUND?
Ultrasound is any sound with a frequency above the range of human hearing, approximately 20 KHz. The most often used frquency band in medical imaging is between 2 and 10 MHz. Sound speed formula: C f Suppose C to be 1540 m/s, the wavelengths in soft tissue are in the range of 0.77-0.154 mm. The high frequencies mean shorter wavelengths.
19
2D Ultrasound Imaging
B-model ultrasound To use the brightness of the screen to display the amplitude of the signal. The greater the amplitude, the greater the brightness of the spot.
14
History of the Development of Ultrasound (III)
After the Korean war, John Julian Wild and John Reid built a linear hand-held B-mode instrument and become the first publication on intensity-modulated cross-section ultrasound imaging.
8
Ultrasound Principle
9
Ultrasound Image (Embryo)
10
Ultrasound: Resolution and Transmission Frequency
Tradeoff between resolution and attenuation -
↑higher frequency ↓shorter wavelength
2
What is SOUND?
来自百度文库
Sound is a mechanical wave that we can hear A mechanical wave can be described by:
Amplitude: a Wavelength: Frequency: f Sound speed: C
Destroy the basal ganglia in patients with Parkinsonism (William Fry, Russell Meyers) Treatment of patients with rheumatic arthritis (Jerome Gersten, 1953)
16
History of the Development of Ultrasound (V)
In 1962, the first commercially available , handheld articulated arm compound contact scanner was produced by engineers William Wright and Edward Meyerdink in USA. The work of Howry and his team is the most important pioneering work in B-mode ultrasound imaging and contact scanning that we have today.
Aluminium 6400 Bone 3500 Liver 1570 Kidney 1560 Blood 1570 Fat 1460 Water 1493 Lung 650 Air 332
4
Properties of Sound Propagation
Sound at different frequency can be transmitted in the same medium at the same speed. The different medium has different speed for sound transmission with the same frequency.
1 C f T
a
3
Sound Propagation Speed
Sound can be transmitted through any mediumgas, liquid, or solid. Sound speed through the medium depends on the compressibility of the medium. The speeds of some materials are shown in the table below. Sound speed in different materials (m/s)
Ultrasound Imaging and Its Applications
Mingyue Ding
Department of Bio-medical Engineering “Image Processing and Intelligent control” Key Laboratory of Education Ministry 2015-7-1
OUTLINES
1. What is ultrasound? 2. History of the development of ultrasound imaging technique 3. 2D ultrasound imaging 4. 3D ultrasound imaging 5. 3D ultrasound imaging applications
11
Frequency Used in US Imaging
To have enough resolution for the observation of human organs, a frequency higher than 0.15 MHz , a wavelength less than 1.0cm, has to be used. Also the frequency will determine the depth of imaging, the lower the frequency, the big the depth will be.
17
Pulse-echo Ranging
D
T C 2
Applications: Bats Sonar system Detects submarines SONAR-Sound Navigation And Ranging.
18
2D Ultrasound Imaging
A-mode ultrasound Horizontal axis is used to represent time while the vertical axis of the signal is to represent the amplitude of the signal.
For abdominal imaging, a frequency between 1.03.0MHz has to be used. For eye examination, a frequency as high as 20 MHz is used. For IVUS imaging, 40 MHz is used.
↑ higher attenuation
Power loss:
dB 1 cm MHz
Typical Ultrasound Frequencies: Deep Body 1.5 to 3.0 MHz Superficial Structures 5.0 to 10.0 MHz e.g. 15 cm depth, 2 MHz, 60 dB round trip Why not use a very strong pulse? Ultrasound at high energy can be used to ablate (kill) tissue. Cavitation (bubble formation) Temperature increase is limited to 1ºC for safety.
13
History of the Development of Ultrasound (II)
Systematic investigations into using ultrasound as a diagnostic tool was made by George Ludwig, a physician at the Naval Research Institute in Bethseda, Maryland in the experiments on animal tissues using pulse-echo ultrasound. “SONICS-techniques for the use of sound and ultrasound in engineering and science” (Theodore Hueter, Richard Bolt) book published in 1954.