Abstract. In medical ultrasound imaging, dynamic range (DR) is defined as the difference between the maximum and minimum values of the displayed signal to display and it is one of the most essential parameters that determine its image quality.
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Why is dynamic range important to an ultrasound image?
Dynamic Range (also known as Compression) allows you to tell the ultrasound machine how you want the echo intensity displayed as shades of gray. A broad/wide range will display more shades of gray and an overall smoother image.
What is dynamic range in echocardiography?
Dynamic range defines the echo strengths shown on the monitor, comparable to the windowing technique in computed tomography. Each received US wave is assigned a gray value and usually displayed on the monitor with 256 gradations.
How does physics relate to ultrasound work?
How will increasing the dynamic range setting affect the ultrasound image?
Increasing the DR yields a higher number of gray scale levels (increased spatial resolution by increased contrast levels) and increased image detail and smoother images. Decreasing the dynamic range increases the contrast of the image, with more black and white areas than shades of gray.
What is range resolution in ultrasound?
The range spatial resolution is an important factor determining the image quality in ultrasonic imaging. The range spatial resolution in ultrasonic imaging depends on the ultrasonic pulse length, which is determined by the mechanical response of the piezoelectric element in an ultrasonic probe.
How do I increase resolution on an ultrasound?
A high frame rate and hence enhanced temporal resolution may be improved by: reduced depth of penetration, since pulses have to travel a short distance; reduced number of focal points, since scan lines do not have to be duplicated; reduced scan lines per frame, using narrow frames rather than wide frames.
How do you optimize an ultrasound image?
- Principles of image optimization in echocardiography. In order to obtain optimal ultrasound images, it is necessary to adjust several parameters continuously during the examination.
- Adjusting image depth and zoom.
- Gain: signal amplification.
- Frequency of ultrasound waves.
- Image focus.
- Frame rate.
What causes reverberation in ultrasound?
A: Reverberation artifact occurs when an ultrasound pulse gets “trapped” between two strong parallel reflectors. The wave reflects back and forth between the reflectors (“reverberates”). The waves that return to the transducer are interpreted as deeper structures since they arrive to the transducer at a later time.
What is frequency in ultrasound?
INTRODUCTION. In physics the term “ultrasound” applies to all acoustic energy with a frequency above human hearing (20,000 hertz or 20 kilohertz). Typical diagnostic sonographic scanners operate in the frequency range of 2 to 18 megahertz, hundreds of times greater than the limit of human hearing.
What is PRF in ultrasound?
PRF is the Doppler sampling frequency of the transducer and is reported in kilo Hertz (KHz). The frequency with which these pulses are emitted determines the maximum Doppler shifts obtainable. The maximum Doppler shift frequency that can be sampled without aliasing is PRF/2, called the Nyquist limit [14].
What is Doppler mode in ultrasound?
A Doppler ultrasound is a noninvasive test that can be used to estimate the blood flow through your blood vessels by bouncing high-frequency sound waves (ultrasound) off circulating red blood cells. A regular ultrasound uses sound waves to produce images, but can’t show blood flow.
What kind of physics is used in ultrasound?
Ultrasound waves can be generated by material with a piezoelectric effect. The piezoelectric effect is a phenomenon exhibited by the generation of an electric charge in response to a mechanical force (squeeze or stretch) applied on certain materials.
Why do you need physics for sonography?
A basic knowledge of ultrasound physics and instrumentation is vital to ensure the correct application of ultrasound for both diagnostic and therapeutic interventions.
Do sonographers use physics?
For convenience, we refer to all such users as sonographers. In most cases, they are not physicists or engineers but clinical practitioners who need to have an applied working knowledge and understanding of the physics and technology behind the ultrasound equipment they use.
Why does the image become brighter when you increase the overall gain on an ultrasound machine?
Gain is a uniform amplification of the ultrasonic signal that is returning to the transducer after it travels through the tissue. So rather than brightening the monitor, the image on the screen is whitened by a uniform margin, as though the returning signal is stronger than it is, to make it easier to see.
What control on the ultrasound machine can change the intensity?
Unit Controls The control that alters the intensity of the ultrasound beam generated from the transducer is often referred to as the power control.
How does frequency affect frame rate?
Remember that FPS is how many frames your custom gaming PCs is producing or drawing, while the refresh rate is how many times the monitor is refreshing the image on the screen. The refresh rate (Hz) of your monitor does not affect the frame rate (FPS) your GPU will be outputting.
What is Q factor in ultrasound?
The Q-factor is the ratio of the center frequency (f0) to the bandwidth. A high Q-factor transducer indicates a narrow bandwidth and a long SPL. High Q” transducers are commonly used in Doppler ultrasound application, where a narrow bandwidth is needed to accurately quantify flow rate.
What factor affects the resolution of an ultrasound image?
Axial resolution is dependent upon various factors, the most important of which being the length of the pulse used to form the beam. This is known as the spatial pulse length (SPL). The shorter the pulse length, the better the axial resolution. In fact the axial resolution limit is defined as being one half of the SPL.
Why is resolution important in ultrasound?
Image resolution determines the clarity of the image. Such spatial resolution is dependent of axial and lateral resolution. Both of these are dependent on the frequency of the ultrasound. Axial resolution is the ability to see the two structures that are side by side as separate and distinct when parallel to the beam.
What improves axial resolution?
Higher frequencies will improve the axial resolution. A shorter pulse length will discern two structures more easily than a longer pulse length.
How can ultrasound improve axial resolution?
The spatial pulse length is determined by the wavelength of the beam and the number of cycles (periods) within a pulse. Therefore, to achieve a higher axial resolution using the shortest spatial pulse length possible and fewer number of pulses is advised.
Why is frequency important in ultrasound?
Ultrasound typically used in clinical settings has frequencies between 2 and 12 MHz. Lower frequencies produce less resolution but have greater depth of penetration into the body; higher frequencies produce greater resolution but depth of penetration is limited.
What is gain and depth in ultrasound?
Hence the Time Gain Compensation (also known as Depth Gain Compensation), is a set of depth-specific slide controls that can be used for echo-signal amplification at different depths (see Figure 5 ). It allows the adjustment of echo-signals in the near-field, mid-field and far field to improve axial resolution.