Bluetooth emergency teleradiology gets green light

The mobility of personal digital assistant technology incorporated into cell phones has attracted attention in the teleradiology field. When combined with Bluetooth technology, PDA phones permit radiologists to access remote PACS when necessary, such as when contacted for emergency consultation by emergency physicians during off hours. Korean researchers were the first to exploit the marriage of these technologies for teleradiologic purposes (J Digit Imaging 2007;20[2]:131-139)."A PACS screen in an emergency room can be shared instantly among on-duty emergency physicians and remote specialists without distortion or image synchronization problems," said Sun Ho Kim, Ph.D., of the Center for Emergency Medical Informatics, Yonsei University, in Seoul.The proposed system has been tested over a CDMA 1x EV-DO network to demonstrate feasibility and evaluate performance. CDMA (code-division multiple access) refers to any of several protocols used in second- and third-generation wireless communications. When combined with 1x EV-DO (evolution-data optimized) protocol, in-office applications can be converged with mobile applications. Hence, PACS can now be accessed from a PDA cell phone.

Kim summarized the procedure:

• emergency physician initiates image transmission by designated one-button click
• PACS terminal captures screen as digital image, compresses it in multiresolution format
• using Bluetooth interface, image is transmitted to emergency physician's PDA phone
• emergency physician's PDA phone relays compressed image received from PACS terminal to remote radiologist's PDA phone over CDMA network

Progressive image compression and security mechanisms (SAFER+) are incorporated in the system to avoid most bandwidth and data exposure issues.

Transmission time is related to the bandwidth performance of Bluetooth and CDMA networks. "Maximum uplink bandwidths of CDMA 1x EV-DO networks and maximum Bluetooth bandwidth are 153 Kbps and 723 Kbps, respectively," Kim said. Measured bandwidth over a CDMA 1x EV-DO is, however, subject to fluctuation, depending on variations such as movement speed of the remote user and number of concurrent users in that cell. Measured Bluetooth bandwidth can vary, depending on the distance between the PACS terminal and the attending physician. The measured mean bandwidths without movement for DCMA 1x EV-DO in an urban setting surrounded by high-rise buildings and for Bluetooth at 5 m are 120 Kbps and 110 Kbps, respectively, Kim said.Tests performed by the Korean researchers show low-resolution images can be transmitted to a remote specialist walking 20 km away within 7.2 seconds for rapid emergency assessment. Fine-resolution image transmission can be achieved within 25.3 seconds, with a compression ratio of 10.