Three-Dimensinal Frontal Imaging Method Using a Ultrasonic Ring Array Probe

items

1. Concept
2. Ring Array Probe
3. Three-Dimensional Image Reconstruction
4. Experimental Results of a Rabbit Heart

1．Concept

Back Ground

With a commercial ultrasonic endoscope, only cross-sectional images can be got. However three-dimensional frontal images can not be obtained.

Advantages

In conventinal ultasonic imaging method which needs scanning an ultrasonic beam, it is impossible to image 2-D or 3-D mea- surement domain. Since scanning speed is restricted by ultra- sonic velocity which is not fast in vivo, there is a time gap in a echogram. On the other hand, beam scanning is not needed and 3-D measurement domain is illuminated by a spherical puls- ed wave in this method. Therefore our method is suitable to image moving objects like blood vessels or human heart.

2. Ring Array Probe

The ring array probe has eight ultrasonic transducers. One of them is used as a transmitter and the others as receivers.

3. Three-Dimensional Image Reconstruction

The three-dimensional image reconstruction is performed as 
follows;
1) the measurement domain is quantized into voxels,
2) the propagation time of the pulsed wave (the tansmit-
   ter → each of the voxels → the receiver) is calcu-
   lated for each receiver,
3) an ultrasonic spherical pulsed wave is transmitted,
4) the echo signals from the objects are received by 
   the seven elements of the ring array, and stored in 
   each memory after A/D conversion,
5) the output data of each receiver at the time corres-
   ponding to the the propagation time are taken from the 
   memory and these are summed,
6) the summed data is converted into intensity and dis-
   played in the 3-D domain.

4. Experimental Results of a Rabbit Heart

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