Online doctors offering advice based on standardized symptoms are the most obvious example. Increasingly, however, remote diagnosis, that is telemedicine, will be based on real physiological data from the actual patient. A group from the University of the Kentucky has shown that by using an off-the-shelf PDA(personal data assistance) such as a Palm Pilot plus a mobile phone, it is perfectly feasible to transmit a patient’s vital signs over the telephone. With this kind of equipment in a first-aid kit, the cry asking whether there was a doctor in the house could well be a thing of the past.
Other medical technology groups are working on applying telemedicine to rural care. And at least one team wants to use telemedicine as a tool for disaster response -- especially after earthquakes. Overall, the trend is towards providing glob al access to medical data and expertise.
But there is one problem. Bandwidth is the limiting factor for transmitting complex medical images around the world -- CT scans being one of the biggest bandwidth consumers. Communications satellites may be able to cope with the short-term needs during disasters, such as earthquakes, wars or famines. But medicine is looking towards both the second-generation Internet and third-generation mobile phones for the future of distributed medical intelligence.
Doctors have met to discuss computer-based tools for medical diagnosis, training and telemedicine. With the falling price of broadband communications, the new technologies should greet an era when telemedicine and the sharing of medical information, expert opinion and diagnosis are common.
The main idea of this passage is ______.

A. what the future of health care is like
B. how online doctors operate on patients
C. first-aid kit found wider uses
D. bandwidth is the limiting factor for transmitting images