Near Field p4 - Articles defining Medical Ultrasound Imaging

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'Near Field' p4

A B C D E F G H I J K L M N O P Q R S T U V W Z

Searchterm 'Near Field' found in 17 articles
1 term [

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Zone

A zone is a focal region of the ultrasound beam. An ultrasound beam can be directed and focused at a transmit focal zone position. The axial length of the transmit focal zone is a function of the width of the transmit aperture.
The field to be imaged is deepened by focusing the transmit energy at progressively deeper points in the body, caused by the beam properties. Typically, multiple zones are used. The main reason for multiple zones is that the transmit energy needs to be greater for points that are deeper in the body, because of the signal's attenuation as it travels into the body.

Beam zones:

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Near zone - the region of a sound beam in which the beam diameter decreases as the distance from the transducer increases (Fresnel zone).

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Focal zone - the region where the beam diameter is most concentrated giving the greatest degree of focus.

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Far zone - the region where the beam diameter increases as the distance from the transducer increases (Fraunhofer zone).

The tightest focus and the narrowest beam widths for most conventional transducers are in the mid-field within the zone where the acoustic lens is focused. The ultrasound beam is less well focused and, therefore, wider in the near and far fields which are superficial and deep to the elevation plane focal zone. The beam width is greater in the near and far fields, making lesions in these locations more subject to a partial volume artifact.

See also Derated Quantity.

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View NEWS results for 'Zone' (3).

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Ultrasound Machine

Ultrasound machines, widely used in medical imaging, are essential tools in the field of diagnostic ultrasound. These devices utilize high-frequency sound waves to create real-time images of internal body structures. Ultrasound machines consist of several key components that work together to generate diagnostic images. These include:

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The transducer is a handheld device that emits and receives sound waves. It converts electrical energy into sound waves and captures the returning echoes to create images.

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The control panel houses the interface where the sonographer adjusts imaging parameters such as depth, frequency, and gain. It allows for customization of imaging settings based on the clinical requirements. The transducer pulse controls change the amplitude, frequency and duration of the pulses emitted from the transducer probe.

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The central processing unit (CPU) serves as the brain of the ultrasound machine, processing the acquired data and transforming it into images. It handles complex calculations, image optimization, data storage and contains the electrical power supplies for itself and the transducer probe.

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The display monitor (oscilloscope, tablet, computer monitor, etc.) showcases the real-time ultrasound images produced by the machine. It provides visual feedback to the sonographer, aiding in the interpretation and analysis of anatomical structures. Handheld ultrasound devices and mobile ultrasound probes can be connected wirelessly to a smartphone or tablet via Bluetooth or WiFi. These end device serves then as the ultrasound monitor.

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Data input and measurements are done with the keyboard cursor (trackball). Ultrasound devices used for handheld point of care ultrasound (HPOCUS) are operated via the touch screen of the control panel.

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Images are captured, reviewed, stored and transmitted digitally, using a standard format for digital imaging and communications in medicine (DICOM). Disk storage devices (FDD, HDD, CD, DVD) are outdated, but may be used in older machines to store the acquired images if no picture archiving and communication system (PACS) connection is possible.

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The displayed ultrasound pictures are usually digitally stored in a PACS. The images from portable ultrasound machines can be stored and conveniently managed on the end device itself, the inserted memory card or in the cloud. With a QR scanner, the images can be accessed via the Internet in the cloud. Often there is also the possibility to get a picture of a baby sonography as a printout.

B-mode machines represent the vast majority of machines used in echocardiology, obstetrical scans, abdominal scans, gynecological scans, etc. B-mode ultrasound machines usually produce the sector (or pie segment-shaped) scans. These ultrasound scans require either a mechanical scanner transducer (the transducer moves to produce the sector scan), or a linear array transducer operated as a phased array.

Ultrasound machines come in different types, each catering to specific clinical needs. The two primary types are stationary and portable ultrasound machines:

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Stationary units are typically larger in size and are installed in dedicated imaging rooms. These machines offer advanced imaging capabilities and a wide range of specialized features. They are commonly found in hospitals, clinics, and university medical centers where comprehensive imaging services are provided.

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Portable units (see Portable Ultrasound Machine), as the name suggests, are compact and lightweight, designed for on-the-go imaging. These machines are highly versatile and offer excellent mobility, allowing healthcare professionals to bring the ultrasound system directly to the patient's bedside. Portable ultrasound machines are particularly useful in emergency settings, rural healthcare facilities, and point-of-care applications.