where expertise comes together - since 1996 -

The Largest Open Access Portal of Nondestructive Testing (NDT)

Conference Proceedings, Articles, News, Exhibition, Forum, Network and more

where expertise comes together
- since 1996 -

TecScan Systems
We offer a complete line of NDT scanners, Immersion Tanks & Gantry systems which incorporate Ultrasonic, Phased Array & Eddy Current technologies.
881 views
Technical Discussions
yuan xu
Student
Texas A&M University, USA, Joined Jan 2000, 4

yuan xu

Student
Texas A&M University,
USA,
Joined Jan 2000
4
02:23 Jun-28-2000
Why I can not image the curve surface in pulse-echo mode?

Dear NDT experts:

I am a graduate student of Biomedical engineering. I am trying to image a muscle with a curved surface(you can just think it is a sphere with a radius of 2cm) buried in fat in pulse-echo mode. I scan the tranducer in one direction and get a 2-D image. The transducer I use is a 1MHz central frequency, 0.6 MHz bandwidth focused transducer, whose active element size is 0.75 inch and focal length is 1 inch. But the image I get is only two parellel lines with the length about 0.5cm , which are perpendicular to the acoustic axis. I just can not get an image of curved surface. Could anyone tell me the reason and how to overcome it?

Thanks!

Best regards

Yuan Xu



 
 Reply 
 
Dipl.-Ing. Martin Heinz
Dipl.-Ing. Martin Heinz
09:04 Jun-29-2000
Re: Why I can not image the curve surface in pulse-echo mode?
Dear Yuan Xu,

for answering exactly a breef description of your experimental setup would be helpful:
Is your muscle sample in a water tank, or are you coupling the sound using ultrasonic gel by contact your transducer on the surface? How do you scan exactly (geometrical setup)? How are the dimensions of your sample muscle? If it is very small ( a few millimeters) , you should get problems to "see" your muscle, because 1 MHz is a very low frequency for medical imaging. Although the acoustic impedance of fat and muscle is not very different, thus you won`t get a very big echo.
Remember that on ultrasonic imaging systems the common used frequency is between 3,5 and about 10 MHz, and there although the difference between muscles and fat is difficult to see, because specle and other ultrasonic artefacts are in the range of the echoes obtained by the dividing layers between fat and muscles. For the characterization of tissue differences commonly very high frequencies are used.

Best regards,

Martin Heinz.





 
 Reply 
 
Dave Lines
R & D,
Diagnostic Sonar Ltd, United Kingdom, Joined Nov 1998, 8

Dave Lines

R & D,
Diagnostic Sonar Ltd,
United Kingdom,
Joined Nov 1998
8
00:20 Jun-29-2000
Re: Why I can not image the curve surface in pulse-echo mode?
: Dear Yuan Xu,

: for answering exactly a breef description of your experimental setup would be helpful:
: Is your muscle sample in a water tank, or are you coupling the sound using ultrasonic gel by contact your transducer on the surface? How do you scan exactly (geometrical setup)? How are the dimensions of your sample muscle? If it is very small ( a few millimeters) , you should get problems to "see" your muscle, because 1 MHz is a very low frequency for medical imaging. Although the acoustic impedance of fat and muscle is not very different, thus you won`t get a very big echo.
: Remember that on ultrasonic imaging systems the common used frequency is between 3,5 and about 10 MHz, and there although the difference between muscles and fat is difficult to see, because specle and other ultrasonic artefacts are in the range of the echoes obtained by the dividing layers between fat and muscles. For the characterization of tissue differences commonly very high frequencies are used.

: Best regards,

: Martin Heinz.

Martin is correct in pointing out the difference in frequency that you are using. Other points that you will have to consider are the dynamic range of the imagings system that you are using and the number of elements in the active aperture.

Your description matches what was seen in the early days of medical ultrasound when viewing the foetal head. The interface behaves more like a specular reflector rather than a scattering surface. The interface perpendicular to the beam reflects back strongly while those at an angle deflect this strong reflection away from the probe.

The early medical imagers had either bi-stable or linear displays and so did not show the full shape. This effect can be significantly improved by logarithmic compression of the received signal which allows the scattered signals from the curved surface to be presented on the same display. Edge-enhancement is also often used on these scanners & this boosts the response all the way round the curve but the dynamic range of the log amp is still the critical factor.

Another feature of current medical imagers is the use of much larger apertures (the group of elements which contribute to the transmit & receive signal for a given beam). The elements at the edges of the active aperture are able to catch these oblique reflections and so help to fill in much of the curved interface.

Dave Lines


 
 Reply 
 
Yuan Xu
Student
Texas A&M University, USA, Joined Jan 2000, 4

Yuan Xu

Student
Texas A&M University,
USA,
Joined Jan 2000
4
09:28 Jul-01-2000
Re: Why I can not image the curve surface in pulse-echo mode?
br>Best Regards


Yuan Xu


-------------
: Dear Yuan Xu,

: for answering exactly a breef description of your experimental setup would be helpful:
: Is your muscle sample in a water tank, or are you coupling the sound using ultrasonic gel by contact your transducer on the surface? How do you scan exactly (geometrical setup)? How are the dimensions of your sample muscle? If it is very small ( a few millimeters) , you should get problems to "see" your muscle, because 1 MHz is a very low frequency for medical imaging. Although the acoustic impedance of fat and muscle is not very different, thus you won`t get a very big echo.
: Remember that on ultrasonic imaging systems the common used frequency is between 3,5 and about 10 MHz, and there although the difference between muscles and fat is difficult to see, because specle and other ultrasonic artefacts are in the range of the echoes obtained by the dividing layers between fat and muscles. For the characterization of tissue differences commonly very high frequencies are used.

: Best regards,

: Martin Heinz.




 
 Reply 
 

Product Spotlight

IntraPhase Athena Phased Array System

The Athena Phased Array system, manufactured by WesDyne NDE Products & Technology, consists of a pha
...
sed array acquisition system and PC running IntraSpect software. A PC is used to perform acquisition, analysis and storage of the data. System hardware is capable of operating up to four data sets with any combination of phased array or conventional UT probes. NOW AVAILABLE IN 64-64 CONFIGURATION.
>

TraiNDE UT

TraiNDE UT is a virtual tool associated with a signal database which simulates real inspection con
...
ditions for numerous applications (Type A/V1 block, DAC block, welds and plates).
>

New PHAsis module for longitudinal weld seam inspection

PHAsis® Phased Array manual ultrasonic spot weld inspection device is now ideally suited for test
...
ing of longitudinally welded seams (e.g. Arplas® seam, short line seams) with a length of 3 to 12 mm.
>

TESTD-PT SYSTEM

Pulse thermography is a non-contact test method that is ideal for the characterization of thin fil
...
ms and coatings or the detection of defects. With a remarquable short test time and a high detection sensitivity, the Telops TESTD-PT is the perfect tool for non- destructive testing. With such high frame rates, it is even possible to investigate highly conductive or diffusive materials.
>

Share...
We use technical and analytics cookies to ensure that we will give you the best experience of our website - More Info
Accept
top
this is debug window