Ultrasonography
Summary
Ultrasound (US) imaging is one of the principle tools of our project. We need ultrasonic instrument to detect the exist of bubbles and the effectiveness and the sensitivity of our end product. So, it is necessary to model the our product's response in the ultrasonic field, explain the phenomenon in our experiments and design better device for our detection.In summary, there are several fundamental purposes in this part:
1. Explain why we can detect such small bubbles in the escherichia coli.
2. Discover the relationship of the signal intensity and density of bacteria.
3. Design better divices and methods for our detection.
Basic Concepts
Basic principle of B-mode ultrasound imaging
The ultrasonic testing method we use is a pulse-echo approach with a brightness-mode (B-mode) display, so does the most primary modern medical ultrasound test [1]. It involves transmitting small pulses of ultrasound waves from a transducer into the determinand. As the ultrasound waves penetrate body tissues of different acoustic impedances along the path of transmission, some are reflected back to the transducer (echo signals) and some continue to penetrate deeper. The echosignals returned from many sequential coplanar pulses are processed and combined to generate an image. Thus, an ultrasound transducer works both as a speaker (generating sound waves) and a microphone (receiving sound waves). The direction of ultrasound propagation along the beam line is called the axial direction, and the direction in the image plane perpendicular to axial is called the lateral direction. Usually only a small fraction of the ultrasound pulse returns as a reflected echo after reaching a body tissue interface, while the remainder of the pulse continues along the beam line to greater tissue depths.
Basic parameters and Settings
Wavelength and Frequency
The wavelength and frequency of US are inversely related, ultrasound of high frequency has a short wavelength and vice versa. The ultrasound wave frequency is determined by the transducer, and the transducers' transmitting frequency we can get range from 4MHz to 44MHz.
Resolution[2]
Spacial resolution has great influence on our detection part. The ability of an ultrasound system to distinguish between two points at a particular depth in tissue, that is to say, axial resolution and lateral resolution, is determined predominantly by the transducer.
Axial (also called longitudinal) resolution is the minimum distance that can be differentiated between two reflectors located parallel to the direction of ultrasound beam. Mathematically, it is equal to half the spatial pulse length spatial pulse length Spatial pulse length is the product of the number of cycles in a pulse of ultrasound and the wavelength. . Axial resolution is high when the spatial pulse length is short.
Lateral resolution, with respect to an image containing pulses of ultrasound scanned across a plane of tissue, is the minimum distance that can be distinguished between two reflectors located perpendicular to the direction of the ultrasound beam. Lateral resolution is high when the width of the beam of ultrasound is narrow.
Temporal resolution is the time from the beginning of one frame to the next; it represents the ability of the ultrasound system to distinguish between instantaneous events of rapidly moving structures, for example, during the cardiac cycle.
Contrast resolution refers to the ability to distinguish between different echo amplitudes of adjacent structures. Contrast agents are used when conventional ultrasound imaging does not provide sufficient distinction between two kinds of tissue. The contrast enhancement phenomenon arises because the impedance for ultrasound in gas is markedly different from that for soft tissue. When such a disparity occurs, ultrasound is reflected strongly from the microbubbles, thus enhancing contrast resolution and visualization of structures of interest. In our project, we use the principle of contrast agents (microbubbles in E.coli) to detect the intestinal tumor tissue.
Interaction with tissue
As the ultrasound waves travel through the tissue, they will interact with it. The ultrasound waves can be absorbed inside the tissue and be reflected, transmitted, scattered on the surface. Reflection-mode (the mode we use) ultrasound images display the reflectivity of the object. The reflectivity depends on both the object shape and the material in a complex way.Two important types of reflections are surface reflections and volumetric scattering.
Surface reflecting happens when ultrasound waves encounter Large planar surface (relative to wavelength λ) boundary between two materials of different acoustic impedances.(figure 1[3])
Fig 1. Reflection and transmission on the interface.
p is pressure (force per unit area) [Pascals: Pa = N/m2 = J/m3 = kg/(m s2)] • v is particle velocity [m/s]. p and v are signed scalar quantities that can vary over space and with time. • Z = p/v is specific acoustic impedance [kg/(m2s)] (analogous to Ohm’s law: resistance = voltage / current) • For a plane harmonic wave: Z = ρ0c, called characteristic impedance • ρ0 is density [g/m3] • c is (wave) velocity [m/s] • Force: 1 dyne = 1 g cm / s2, 1 newton = 1 kg m / s2 = 1·106 dyne
Device Design
xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx. The text-link template is here.
2018 Interlab Plate Reader ProtocolProtocols/Transformation
Bubbles's Response Model
xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx The figure template is here.
Fig 1. The particle standard curve obtained form the 2nd calibration experiment.
xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx.
The table template is here.
Table 1. Colony forming units per 0.1 OD600
| samples | dilution factor | CFU/mL | ||
|---|---|---|---|---|
| 8×104 | 8×105 | 8×106 | ||
| 1.1 | TNTC | 48 | 11 | 3.84E+07 |
| 1.2 | 248 | 41 | 10 | 3.28E+07 |
| 1.3 | 172 | 54 | 5 | 4.32E+07 |
| 2.1 | TNTC | 143 | 20 | 1.14E+08 |
| 2.2 | TNTC | 153 | 25 | 1.22E+08 |
| 2.3 | TNTC | 151 | 18 | 1.21E+08 |
| 3.1 | TNTC | 119 | 16 | 9.52E+07 |
| 3.2 | TNTC | 125 | 19 | 1.00E+08 |
| 3.3 | TNTC | 89 | 18 | 7.12E+07 |
| 4.1 | TNTC | 209 | 16 | 1.67E+08 |
| 4.2 | TNTC | 130 | 17 | 1.04E+08 |
| 4.3 | TNTC | 164 | 10 | 1.31E+08 |
Section5
XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX
Reference
[1] Chan V, Perlas A. Basics of ultrasound imaging[M]//Atlas of ultrasound-guided procedures in interventional pain management. Springer, New York, NY, 2011: 13-19.
[2] Alexander Ng, Justiaan Swanevelder; Resolution in ultrasound imaging, Continuing Education in Anaesthesia Critical Care & Pain, Volume 11, Issue 5, 1 October 2011, Pages 186–192.
[3] Chapter U. Reflection-mode ultrasound imaging[J].
[4] Chapter U. Reflection-mode ultrasound imaging[J].
