2010 Group Project 1: Difference between revisions
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==How It Works== | ==How It Works== | ||
The basic principle of ultrasound is similar to that of sonar – that is, sending out pulses of high-frequency sound waves, receiving back the echoes of those waves after they bounce off surrounding materials, and constructing a picture of those materials from the received sounds | The basic principle of ultrasound is similar to that of sonar – that is, sending out pulses of high-frequency sound waves, receiving back the echoes of those waves after they bounce off surrounding materials, and constructing a picture of those materials from the received sounds. In medical ultrasound, or sonography, pulses of ultrasound are sent into the body where they bounce off the edges of organs and tissues, relaying that anatomical information back to the ultrasound machine.<ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5</ref> | ||
There are three main elements in an ultrasound system: | There are three main elements in an ultrasound system: | ||
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The transducer is the piece of equipment in contact with the patient. It emits the ultrasound pulses and receives the echoes of those pulses. Since air diminishes the integrity of the ultrasound signals, a medium such as a water-soluble gel is applied between the transducer and the patient’s skin to improve the interface between the two ( | The transducer is the piece of equipment in contact with the patient. It emits the ultrasound pulses and receives the echoes of those pulses. Since air diminishes the integrity of the ultrasound signals, a medium such as a water-soluble gel is applied between the transducer and the patient’s skin or body structure to improve the interface between the two (similar to the way that oil is applied to a high-power microscope objective to decrease distortion of the image by refraction and scattering). There are several kinds of transducers producing different kinds of ultrasound images, discussed below. Transducers can be non-invasive (for prenatal diagnosis, pressed against the woman's pelvis or abdomen) or they can be invasive (transvaginal transducers, for example, are inserted into the vagina to obtain better views of the ovaries, fallopian tubes, uterus, and surrounding structures).<ref>Ellwood, D.A. (1995) The Role of Ultrasound in Prenatal Diagnosis. In Trent, R.J. (Ed.), Handbook of Prenatal Diagnosis. Cambridge, England: Cambridge Uiversity Press, pp. 28-31</ref> | ||
Within the transducer are elements made of silicon crystals. The pulses of ultrasound are created using the pizoelectric effect – when silicon crystals experience electrical impulses they mechanically deform on a microscopic level, producing high-frequency sound waves. Returning sound waves (echoes) will similarly deform the silicon crystals, and these deformations are converted to electrical impulses which are then sent to the ultrasound machine for processing. Different kinds of transducers will produce different kinds of images, or scans. Linear or curvilinear transducers generate rectangular images with a wide viewing field. Phased array transducers create a sector image by electronically “phasing” the elements to give off pulses. High-frequency transducers (5MHz or greater) give better resolution of images, but low frequency transducers penetrate deeper into tissues and so give deeper images. <ref>Ellwood, D.A. (1995) The Role of Ultrasound in Prenatal Diagnosis. In Trent, R.J. (Ed.), Handbook of Prenatal Diagnosis. Cambridge, England: Cambridge Uiversity Press, pp. 28-31</ref> | Within the transducer are elements made of silicon crystals. The pulses of ultrasound are created using the pizoelectric effect – when silicon crystals experience electrical impulses they mechanically deform on a microscopic level, producing high-frequency sound waves. Returning sound waves (echoes) will similarly deform the silicon crystals, and these deformations are converted to electrical impulses which are then sent to the ultrasound machine for processing. Different kinds of transducers will produce different kinds of images, or scans. Linear or curvilinear transducers generate rectangular images with a wide viewing field. Phased array transducers create a sector image by electronically “phasing” the elements to give off pulses. High-frequency transducers (5MHz or greater) give better resolution of images, but low frequency transducers penetrate deeper into tissues and so give deeper images. <ref>Ellwood, D.A. (1995) The Role of Ultrasound in Prenatal Diagnosis. In Trent, R.J. (Ed.), Handbook of Prenatal Diagnosis. Cambridge, England: Cambridge Uiversity Press, pp. 28-31</ref> | ||
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The other basic part of the ultrasound system is the recording equipment – that is, a range of devices such as multiformat cameras, video printers and video recorders used to store information from the patient’s examination.<ref>Ellwood, D.A. (1995) The Role of Ultrasound in Prenatal Diagnosis. In Trent, R.J. (Ed.), Handbook of Prenatal Diagnosis. Cambridge, England: Cambridge Uiversity Press, pp. 28-31</ref> | The other basic part of the ultrasound system is the recording equipment – that is, a range of devices such as multiformat cameras, video printers and video recorders used to store information from the patient’s examination.<ref>Ellwood, D.A. (1995) The Role of Ultrasound in Prenatal Diagnosis. In Trent, R.J. (Ed.), Handbook of Prenatal Diagnosis. Cambridge, England: Cambridge Uiversity Press, pp. 28-31</ref> | ||
Sending one ultrasound pulse into the body will generate a line of dots – this represents one line of echo information, or one scan line. (DIAGRAM) Not all of that pulse bounces back off one single anatomical structure; instead, most of the pulse continues through to deeper structures where some of the pulse bounces back from each structure it passes through. This is what generates the line of dots representing an internal view of the patient. Since the echoes of a single pulse generate one scan line of information, generating several pulses parallel to one another in a line will generate a cross-sectional image of the patient (DIAGRAM). This would generate a rectangular image or linear image of the patient. An alternative to this is to generate all the pulses from the same starting point, but have subsequent pulses move in slightly different directions, creating a sector scan which is shaped like a fan (DIAGRAM OF LINEAR VS SECTOR SCANS). A modified sector scan combines the two – pulses begin from several different areas and also travel in different directions, creating a fan shape but with a curved top (DIAGRAM). <ref>Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-9</ref> | |||
===Doppler Ultrasound=== | ===Doppler Ultrasound=== | ||
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===Comparison of Ultrasound Imaging Types=== | ===Comparison of Ultrasound Imaging Types=== | ||
==Current Uses in Prenatal Diagnosis== | ==Current Uses in Prenatal Diagnosis== | ||
Revision as of 13:18, 2 September 2010
Ultrasound
Introduction
History
How It Works
The basic principle of ultrasound is similar to that of sonar – that is, sending out pulses of high-frequency sound waves, receiving back the echoes of those waves after they bounce off surrounding materials, and constructing a picture of those materials from the received sounds. In medical ultrasound, or sonography, pulses of ultrasound are sent into the body where they bounce off the edges of organs and tissues, relaying that anatomical information back to the ultrasound machine.[1]
There are three main elements in an ultrasound system:
- The transducer
- The machine
- Recording devices
The transducer is the piece of equipment in contact with the patient. It emits the ultrasound pulses and receives the echoes of those pulses. Since air diminishes the integrity of the ultrasound signals, a medium such as a water-soluble gel is applied between the transducer and the patient’s skin or body structure to improve the interface between the two (similar to the way that oil is applied to a high-power microscope objective to decrease distortion of the image by refraction and scattering). There are several kinds of transducers producing different kinds of ultrasound images, discussed below. Transducers can be non-invasive (for prenatal diagnosis, pressed against the woman's pelvis or abdomen) or they can be invasive (transvaginal transducers, for example, are inserted into the vagina to obtain better views of the ovaries, fallopian tubes, uterus, and surrounding structures).[2]
Within the transducer are elements made of silicon crystals. The pulses of ultrasound are created using the pizoelectric effect – when silicon crystals experience electrical impulses they mechanically deform on a microscopic level, producing high-frequency sound waves. Returning sound waves (echoes) will similarly deform the silicon crystals, and these deformations are converted to electrical impulses which are then sent to the ultrasound machine for processing. Different kinds of transducers will produce different kinds of images, or scans. Linear or curvilinear transducers generate rectangular images with a wide viewing field. Phased array transducers create a sector image by electronically “phasing” the elements to give off pulses. High-frequency transducers (5MHz or greater) give better resolution of images, but low frequency transducers penetrate deeper into tissues and so give deeper images. [3]
Information about the patient’s tissues is generated by calculating the time it takes for the ultrasound pulses to bounce off those tissues and travel back to the transducer. The ultrasound waves will take longer or shorter amounts of time to travel through different tissues depending on their properties. A real-time image of the patient is generated by rapidly turning the elements in the transducer on and off, allowing the generation of many still frames in a small amount of time.[4]
The ultrasound machine itself is comprised of the computer hardware and software needed to convert the signals picked up by the transducer into an image that can be viewed. The image is in greyscale, using various shades from black to white to indicate different tissues and tissue features (PICTURE.)[5]
The other basic part of the ultrasound system is the recording equipment – that is, a range of devices such as multiformat cameras, video printers and video recorders used to store information from the patient’s examination.[6]
Sending one ultrasound pulse into the body will generate a line of dots – this represents one line of echo information, or one scan line. (DIAGRAM) Not all of that pulse bounces back off one single anatomical structure; instead, most of the pulse continues through to deeper structures where some of the pulse bounces back from each structure it passes through. This is what generates the line of dots representing an internal view of the patient. Since the echoes of a single pulse generate one scan line of information, generating several pulses parallel to one another in a line will generate a cross-sectional image of the patient (DIAGRAM). This would generate a rectangular image or linear image of the patient. An alternative to this is to generate all the pulses from the same starting point, but have subsequent pulses move in slightly different directions, creating a sector scan which is shaped like a fan (DIAGRAM OF LINEAR VS SECTOR SCANS). A modified sector scan combines the two – pulses begin from several different areas and also travel in different directions, creating a fan shape but with a curved top (DIAGRAM). [7]
Doppler Ultrasound
3D Ultrasound
Comparison of Ultrasound Imaging Types
Current Uses in Prenatal Diagnosis
Subheadings: Normal uses during pregnancy/Diagnosing abnormalities?
Risks and Regulations
Current Research and Future Uses in Prenatal Diagnosis
Advantages and Disadvantages
Glossary
Linear image: A rectangular image produced by a transducer with elements next to each other, giving off ultrasound pulses in parallel lines
Modified sector scan: A fan-shaped image with a curved top produced by a transducer with elements next to each other that also emit pulses in different directions
Pizoelectric effect: When silicon crystals experience electrical impulses they mechanically deform on a microscopic level, producing high-frequency sound waves
Pulse-echo technique: A technique in ultrasound where short pulses of ultrasound are emitted into the area to be studied, and echoes are received and interpreted to give information about the internal anatomical structures by calculating the time taken for the ultrasound echoes to return to the transducer
Scan line: the line of dots representing the information from one pulse of ultrasound
Sonographer: a trained ultrasound technician
Sonography: medical anatomical imaging using ultrasound
Sonologist: a medical practitioner who is a trained ultrasound technician
Sector scan: A fan-shaped image produced by a transducer with ultrasound pulses emitting from the same point but in different directions
Transducer: The part of the ultrasound apparatus that is in contact with the patient; it emits the pulses and receives the echoes of ultrasound
References
- ↑ Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-5
- ↑ Ellwood, D.A. (1995) The Role of Ultrasound in Prenatal Diagnosis. In Trent, R.J. (Ed.), Handbook of Prenatal Diagnosis. Cambridge, England: Cambridge Uiversity Press, pp. 28-31
- ↑ Ellwood, D.A. (1995) The Role of Ultrasound in Prenatal Diagnosis. In Trent, R.J. (Ed.), Handbook of Prenatal Diagnosis. Cambridge, England: Cambridge Uiversity Press, pp. 28-31
- ↑ Ellwood, D.A. (1995) The Role of Ultrasound in Prenatal Diagnosis. In Trent, R.J. (Ed.), Handbook of Prenatal Diagnosis. Cambridge, England: Cambridge Uiversity Press, pp. 28-31
- ↑ Ellwood, D.A. (1995) The Role of Ultrasound in Prenatal Diagnosis. In Trent, R.J. (Ed.), Handbook of Prenatal Diagnosis. Cambridge, England: Cambridge Uiversity Press, pp. 28-31
- ↑ Ellwood, D.A. (1995) The Role of Ultrasound in Prenatal Diagnosis. In Trent, R.J. (Ed.), Handbook of Prenatal Diagnosis. Cambridge, England: Cambridge Uiversity Press, pp. 28-31
- ↑ Kremkali, F.W. (2006) Diagnostic Ultrasound Principles and Instruments (7th ed.) St Louis: Saunders Elsevier. pp3-9
2010 ANAT2341 Group Projects
Project 1 - Ultrasound | Project 2 - Chorionic villus sampling | Project 3 - Amniocentesis | Group Project 4 - Percutaneous Umbilical Cord Blood Sampling | Project 5 - Fetal Fibronectin | Project 6 - Maternal serum alpha-fetoprotein | Group Assessment Criteria
Glossary Links
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Cite this page: Hill, M.A. (2024, April 30) Embryology 2010 Group Project 1. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/2010_Group_Project_1
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G
