Talk:Ultrasound

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    [edit] Comment 1

    This articles needs one or more sources, added tag.--FloNight 23:38, 26 November 2005 (UTC)

    [edit] Why can't humans hear ultrasound?

    Why can not human being hear sounds more than 20 kilohertz??

    Because above 20,000 Hertz (vibrations per second) the waves are too small and fast for the inner ear to transmit the vibrations. 20,000 Hertz is the typical upper limit of hearing, there may be individuals who can detect some frequencies slightly above this range, but not much higher. DuBose 14:06, 11 November 2005 (UTC)
    It should perhaps also be noted that this limit is lower for many persons - it decreases with age, and it is also decreased by repeated exposure to high-intensity sounds of lower frequencies (loud music being a common example). Osquar F 12:33, 5 December 2006 (UTC)

    WHATS THE STORY IN BALAMORY WOULDN'T YOU LIKE TO KNOW? NO!!!!!!!!!! —Preceding unsigned comment added by 81.132.224.222 (talk) 20:26, 3 December 2007 (UTC)

    [edit] Sonography

    Does anyone know why medical sonography uses a typical frequency of 1 to 10 MHz. Why not higher? Are there any constraints on this?

    -- I believe this is due to regulations on transmitted power - higher the frequency, the higher the energy in the transmission. To prevent localized heating, the transmitted energy (and thus the frequency) are limited. Also, the upper limit is more like 15MHz, IIRC, although that's flexible depending on the specific application.

    -- In addition, attenuation of an ultrasound beam is proportional to its frequency, which means that a 10MHz medical imaging beam can only penetrate around 3cm at "safe" power levels. Only very superficial structures can be scanned in this way. Higher frequencies can be used in small children where the size and relative depths of structures of interest are smaller, and can also be used in adults in situations where a modified probe can be put inside the body. Examples of this are trans-esophageal echocardiography, transvaginal sonography and intravascular ultrasound imaging.

    -- There are actually applications for ultrasound at higher frequency. A new field appeared about 10 years ago, which focuses on small animal imaging, in particular mouse and rat imaging. It is often referred to as ultrasound bio-microscopy (UBM). The frequency for UBM typically ranges from 20 MHz to 60 MHz, which translates to a resolution of 25 to 75 µm axially and about 50 to 150 µm laterally (depending on the geometry of the tranducer). Biology labs and pharmaceutical companies are the principal users of this technology, because it allows them to visualize the progression of model of diseases (for example cancer model) developed in small animals without having to sacrifice these animals at regular time interval (like it used to be done when histology only could provide information about diseased tissues). The efficiency of particular disease treatments can also benefit from this technology. Also, ultrasound scanners are also on the market for specific human applications. Intra vascular ultrasound is one of them (30-40 MHz, typically). Opthalmology is also an application for which high frequency ultrasound scanners are commercialized (20 MHz for imaging of the retina, 40-50 MHz for imaging of the cornea). Dermatology could also benefit from UBM technology.

    The increase of the attenuation as a function of frequency is for sure an issue when dealing with high frequency ultrasound, especially because it limits the depth of penetration (UBM scanner can image at a maximum depth of around 10 to 20 mm, depending on the frequency used). However, another type of limitations has prevented for a long time higher frequency to be used for imaging. And it has to do with the capability (or motivation, the market was maybe not there yet) of manufacturers to develop transducers operating in the high frequency range. To date, commercially available UBM scanners are still using a single element transducer collecting data from one particular location, and mechanically scanned across the sample to produce images. This mechanical scan limits drastically the imaging frame rate (60 fps, typically). Furthermore, the use of single element transducers limit the number of focal zones to a single one. Whereas in the clinical frequency range, single element transducers have been replaced a long time ago by transducers array, which in combination with beamforming techniques, can generate multiple foci, can steer the beam, and can scan across the sample without being actually physically moved spatially, allowing for frame rate well above 100 frames per second. Some research labs around the world are however working on the development of transducers array for UBM, but it is a very challenging task, because structures in these arrays that are 100's microns in size, would have to be let say 10 times smaller for high frequency arrays.

    You seem to be changing every use of "ultrasonography" with "sonography". I wish you'd discussed this on the relevant talk pages first. I think the correct term is "ultrasonography" if the test is called "an ultrasound". I've changed it back for now. Please provide some support for your changes. JFW | T@lk 14:32, 11 November 2005 (UTC)

    If you think the article medical ultrasonography should be called sonography instead, please do not create a duplicate page but suggest a move on the former page. JFW | T@lk 14:37, 11 November 2005 (UTC) Retrieved from "http://en.wikipedia.org/wiki/User_talk:DuBose"

    I do disagree with the term ultrasonography and ultrasound in this context. There is a historical place for the term ultrasound; however, ultrasound is a term of physics meaning frequencies above human hearing; you obviously know this. Ultrasound is not unique to medical imaging. Many use “ultrasound” for medical and non-medical purposes. Physical Therapists use it for deep heat, Dental Hygienist use it to clean teeth, Iron Workers use it for non-destructive testing, and jewelers use it to clean rings and watches. Only sonographers use ultrasonic energy to create medical images. Sonography, sonographer, and sonographic were coined 30 years ago to specifically refer to this type of medical imaging. Ultrasonography is unnecessarily long, pretentious, and redundant because the “ultra” goes without saying. Sonography is simple, unique, and specific to the profession.

    While ultrasound predates the term sonography and its derivatives, sonography is much more consistent with older medical nomenclature such as radiography. And while we use ultrasonic energy to create these images, to refer to the technique or image as an “ultrasound” is analogous to referring to a photograph as a “light”… photographs are reflected light.

    Sonography, Sonographer, & Sonographic are well accepted and because they are unique to the profession are more specific to it. There are ample examples of the acceptance of these terms:

    Definitions of sonography on the Web: • A imaging technique for visualizing the growth of ovarian follicles during infertility therapy. http://www.infertilitycentral.com/fertility/infertility-glossary,6.html • use of sound to form images eg ultrasound scanning http://www.nutrition-matters.co.uk/misc/glossary.htm • An imaging test which sends sound waves to and receives them back from an organ to create an image of that organ. http://www8.utsouthwestern.edu/utsw/cda/dept22047/files/144495.html • using the reflections of high-frequency sound waves to construct an image of a body organ (a sonogram); commonly used to observe fetal growth or study bodily organs wordnet.princeton.edu/perl/webwn DuBose 22:03, 11 November 2005 (UTC)

    This discussion should be conducted on talk:medical ultrasonography and not here. JFW | T@lk 01:50, 13 November 2005 (UTC)

    [edit] ultrasound communication for underwater

    Does anyone know anything about the communication devices used by divers?--Gbleem 01:28, 22 November 2005 (UTC)

    " to refer to the technique or image as an “ultrasound” is analogous to referring to a photograph as a “light”… photographs are reflected light."

    Is this not what people do when they call a light-produced image a "photo"?

    [edit] Ultrasound definition and Principles

    [edit] Principles

    The principles of ultrasound are the same irrespective of the application. Several contributors have defined ultrasound in terms of its use in medicine, with little more than a cursory nod toward it's use in industry. Although in modern times the use of ultrasound is much more widespread in medicine and thus more familiar to the public at large, it is in a comparitively narrow field and uses a small range of frequencies, in the MHz range, which are suited to human tissue and bone. In industrial nondestructive testing (NDT) the uses are far more varied and the range of frequencies varies from 100's of Khz up to many Ghz. Such applications include, crack detection and sizing, bond testing, material evaluation and ultrasonic microscopy. Hardware ranges from single probe in pulse-echo mode - ie sending and receiving its own pulse, thru inspection systems used in the oil and gas industry containing many probes up to multi-element arrays capable of producing a real-time image of the object under test (herein lies the parallel with medical imaging).

    [edit] Definition

    Quite correctly, ultrasound is defined as "above the frequency at which the average human can hear", i.e. approximately 16khz but then the rather bold statement is made that because Bats and certain other animals' threshold is higher, "they can hear Ultrasound". This is very misleading. Admittedly, certain species of bat can hear up to 160 khz but this is a minute proportion of the full spectrum of Ultrasound, which as I have already said is well into the Ghz range.

    Ghz range is not, and can not be used in industrial applications; inspections of metals. The grain structure of the material becomes obvious far below the Ghz range. The sound beam would not have the penetrating power to accurately allow for cogent interpretation. 5 Mhz is capable of sizing a defect to 0.5 mm. Even 10 Mhz is seldom used.

    It is important to distinguish between industrial application of Ultrasond and the full spectrum to which the term Ultrasound can be applied. You cannot claim that "5MHz can size a defect to 0.5mm", without specifying the material, the grain size and the technique being used.

    Ultrasound is indeed used up to the range of GHz in Acoustic microscopes. It is used well into the 20 and 30 MHz range for example in bond testing between Aluminium substrates.

    May I suggest some slight changes to the ultrasound page to encompass the various interpretations of the word "ultrasound". I think the opening section is looking good - it states the technical definition of the word, and briefly covers the various applications. But then the rest of the article assumes ultrasound == sonography, which is at odds with the opening. Here's my suggestion:

    The opening remains in close to its current form, with technical definition and common applications/interpretations.

    The next section is "From sound to image (sonography)" which includes dangers, producing, receiving, displaying, all covered in a scientific manner. Then a link is provided to the "medical ultrasonography" page for more practice perspective info.

    Then a section is added "From sound to graph (ultrasound testing)" which covers the NDT/NDE applications of ultrasound, in a scientific manner. I'm happy to provide a first draft for this section.

    Perhaps the baby in womb picture could be moved to "medical ultrasonography" and a frequency spectrum graph inserted instead?

    LightYear 00:02, 24 January 2006 (UTC)

    [edit] ESWL is not Ultrasound

    Extracorporeal shock wave lithotripsy is not an ultrasound application. Seejyb 23:54, 14 November 2006 (UTC)

    [edit] Additional images?

    Currently, all of the images are of fetuses. These are definitely valuable pictures for this article, as that's a common and well-known use of ultrasounds. I think it would also be beneficial, however, to have an image or two of other medical ultrasounds to further illustrate (no pun intended) that they have other medical uses as well. I don't have any, unfortunately, but it would be a nice addition if someone does. Maybe the CDC website or another US Government health-related department would? Just throwing that out there, as images by the US Government don't have the same copyright issues. --Icarus (Hi!) 18:47, 31 December 2006 (UTC)

    Since this article is about ultrasound, the frequency range, and its various applications, I've relegated one of the medical images to the medical section, and added a rough diagram of the ultrasound spectrum. LightYear 01:18, 11 January 2007 (UTC)

    We must not forget about our four legged friends. Ultrasound is growing rapidly in the field among veterinarians and animal breeders alike. Cost reductions due to R&D, and affordable units introduced from China have pushed the cost down drastically on diagnostic ultrasound units, so that the introduction of this tool into communities other than hospital and physician offices has increased very rapidly. Please see the several diagnostic images used for but not limited to equine, swine, cattle, cats and dogs at http://www.ameritechmedical.com/vet_ultrasounds.htm —Preceding unsigned comment added by AmeritechMed (talk • contribs) 15:53, 29 February 2008 (UTC)

    [edit] Non-linear propagation

    I really like this paragraph, but it just doesn't fit in this article at the moment. LightYear 01:18, 11 January 2007 (UTC)

    ==Nonlinear Effects of Propagating Acoustic Wave== When an acoustic wave propagates through a material, it acts as a force that creates localized pressure. When a material is under pressure (as compared to some lower equilibrium pressure), the speed of sound increases because the molecules transmitting the energy are closer together. As a result, the wave travels faster during the high pressure phase than for the lower pressure section of oscillation. Consider a sinusoidal wave with a high peak. As a result of this nonlinear effect, the peaks of the wave travel faster than the dips (near zero). When the peaks travel faster, the shape of the wave changes, as the higher amplitude sections shift farther forward than the lower pressure part of the wave and the signal approaches more of a square wave than a sinusoidal one. Fourier analysis will show that this single-frequency wave will be changed into one that has much more than a single impulse in the frequency domain! This implies a non-linear system, as a linear one cannot output frequencies that were not a part of the input signal.

    It is relevant to how ultrasound operates. I have restored it, until someone finds somewhere else to put it. Anthony Appleyard 06:57, 11 January 2007 (UTC)

    I really like it too, but I agree that it should go somewhere else. Right now I'm thinking of moving it to the "wave" article, although that's not exactly right either. Ideally there should be an article on non-linear wave propigation for this information, but it would need more mathematical models and some sources.Dudecon 19:06, 12 January 2007 (UTC)
    okay, I looked around and this kind of non-linear behaviour only occurs in pressure waves. This is primarily an acoustic effect, so it should go in an acoustic related article. I've created a stub for Nonlinear Acoustics and coppy-pasted the paragraph there as a seed. I don't know much about the topic personally, so I tagged it for attention by an expert. —The preceding unsigned comment was added by Dudecon (talk • contribs) 19:37, 12 January 2007 (UTC).

    [edit] "younger humans": the mosquito ring tone.

    I'm not saying that children can't hear it, I'm saying that most adults can and the NYT is full of baloney on this point. I'm 40 with a long history of listening to music much louder than I should and I can hear it clearly from a considerable distance, as can my 38 yr old wife, and co-workers ranging in age from 42 to 60. This is just silliness. Additionally, the statement begins, "Some have said that children can hear some high-pitched sounds that older adults cannot hear..." The sole reference does back up the point that there is a bogus ring tone that was alledgedly created (or at least used) because adults supposedly can't hear it, however untrue that reality may be, but there is no reference to back up the assertion that children (as a rule) can hear sounds that adults cannot (as a rule) hear. Darentig 16:56, 5 April 2007 (UTC)

    I agree the info on a mobile phone ring tone is trivial at best and nonsense at worst. I propose cleaning this section up by removing the mention of the ring tone, and explicitly stating that the upper limit of hearing is different for different folks, and that in general, this upper limit comes down as age increase. We are all happy to agree on this as fact, are we? LightYear 04:29, 10 April 2007 (UTC)
    It is definitely true that many adults over the age of around 40 begin to lose some of the very-highest-frequency hearing, and that this loss progresses into old age; I've added a reference about this to the article. The enormous variation in this phenomenon across the population means that, although the ringtone's creation has some basis in fact, it's essentially pointless because a significant proportion of adults will easily hear it. I do not think that the ringtone paragraph should be removed - it helps make the topic interesting to the casual reader. --mcld 20:41, 10 April 2007 (UTC)
    Sounds (haha) good. Thanks for the edit. I'm happy with that section now. LightYear 23:24, 10 April 2007 (UTC)

    [edit] Link clean-up

    None of the external links satisfied Wikipedia:External links, so I deleted them all. Details are given below. We need to find links of the "further reading" type, that provide more (and relevant) detail than is included here.

    • A special issue of Progress in Biophysics & Molecular Biology that focuses on ultrasound and infrasound — requires purchase
    • American Institute of Ultrasound in Medicine (Professional Association) — move to Medical ultrasonography
    • Ultrasound Safety Issues — move to Medical ultrasonography
    • Radiology Web Site Directory — nothing to do with ultrasound
    • Ultrasound Job Outlooks — nothing to do with the topic
    • Radiology Resources for Students and Professionals — nothing to do with ultrasound
    • Ultrasound Can Affect Fetal Brain Development — move to Medical ultrasonography
    • 3D Ultrasound Info - Includes sample images and studies — commercial site
    • Yahoo email groups:- — discussion forums usually not recommended

    — DavidMack 23:02, 4 July 2007 (UTC)

    • The Internation Ultrasound Forum [www.ultrasoundforum.com], nonprofit dicussion board.

    Extracorporeal Shock Wave Lithotripsy does not involve ultrasound jmak 08:53, 5 July 2007 (UTC)

    [edit] Emphasis on medical ultrasound risks rather that diagnostic use?

    Does it seem odd to anyone else that there is more content regarding the risk and dangers of ultrasound for medical purposes than there are in the dedicated 'Medical ultrasonography' page? I thought that for the page on general 'Ultrasound', there should be more about the various uses of ultrasound in diagnostic medicine rather than several paragraphs on the risks of it. Saket (talk) 04:40, 8 December 2007 (UTC)

    Perhaps all the content on risks and dangers which is now on both pages should be collected at Medical ultrasonography#Risks and side-effects. If that is done, then on this Ultrasound page there could be just one sentence saying that the risks and dangers are discussed further in the Medical ultrasonography article with an appropriate link. Dirac66 (talk) 20:17, 8 December 2007 (UTC)