A compression and transmission method of
ultrasound RF signal for tele-diagnosis

Toshihiro Seko

abstract
　Health-care is a critical issue nowadays. Much emphasis is given to the quality care for all people. The tele-diagnosis attract public attention. We propose a new method of ultrasound image transmission for tele-diagnosis. In conventional methods, video image signals have been transmitted. In our method, the RF signals which are acquired by ultrasound probe, is transmitted. The RF signals can be transformed to color Doppler images or high resolution images by receiver.
　In this research, I describe a lossless compression method which is specialized in transmission of the RF signals. One of the methods uses the character of the RF signal. Another method, quantity of the data is reduced.

keyword
　{tele-diagnosis, ultrasound, RF signal, lossless compression,store form}

[ Introduction] [System]

Introduction
　Tele-diagnosis means that a medical specialist (after this, it is called with the place 'diagnosis site' which medical specialist is in.) diagnosis a transmitted image that was took picture in remote site (after this, remote site is called 'measurement site' of medical environment).
Benefits of tele-medicine are the leveling of regional differences, improvement of efficiency of medical care, and improvement of service for patients. Moreover tele-medicine can be a very effective method of international medical cooperation.
X-ray image, MRI image, ultrasound image and some medical images are used for the tele-diagnosis. The quality of ultrasound image is bad in comparison with others. But ultrasound image has some advantages for the tele-diagnosis.
The advantage are;
　1) ultrasound is noninvasive
　2) ultrasound device is cheep
　3) ultrasound equipment can capture dynamic images of the human organ
　4) ultrasound equipment doesn't need special facilities
　5) ultrasound equipment high diffusion.

Tele-diagnosis system has two forms (store form, real-time form). 　 　In conventional tele-diagnosis which use dynamic ultrasound image, standard video image signal or scan-line signal is compressed and transmitted. In these method, the process of converting RF signal (RF signal is raw ultrasound echo signals) into the the video signal injures asailable for information for medicine, such as a frequency shift (Doppler can be calculated fromfrequency shift), information of characteristics of tissue (Information on the %change received when ultrasound permeated or reflected organization.).
　 In this research, we propose to use RF signal to keep that information for tele-diagnosis by this system based on a store form. The receiver can transform the RF signal to color Doppler, high-resolution images and etc.
　Tele-medicine in home hearth (tele-care) can be used for patients who are in stable condition and who have received medical care from the same doctor for a long time.
This system is thought to be more effective in the tele-care. The measurement site consists of probe (include pulse generator), PC and network, this system is very useful for tele-care. In the measurement site, scanning data are stored in exclusive space. In diagnosis site, a doctor can access (request) data and acquire data. A doctor can have discussion with other doctors by using those data, as other function.

return top

System
 　System overview is shown in Figure 1.


Figure 1　system overview

First PC acquires RF signal from ultrasound diagnosis device in measurement site. Second, data compressed and stored in PC. Next, in diagnoses site, a medical specialist accesses and acquires data from measurement site. Finally, a medical specialist diagnosis data. If it is used for tele-care, data are updated at the fixed time of every day, and it thinks that a doctor does a diagnosis at the fixed time, too. %Time of everyday seeing a doctor regularly of the patient who has a This is convinient for the patient who has a chronic disease can be saved.
　The timing of data acquisition in the ultrasound equipment is shown in Figure 2.


Figure 2　Timing of data acquisition

In conventional methods, data were acquired at the timing of a point (2) or (3) in Figure 2 (after this, each data which is caused with scan-line signals, video signals). In propose method data acquisition is done at the timing of a point (1) in Figure 2. (RF signal) to prevent lose of the information.