Richard Vercillo

Development Of A High Resolution X-Ray Imaging Device For Use In Coronary Angiography

This paper describes a high resolution x-ray imaging device which is being developed through NIH sponsorship by the University of Arizona. It consists of an external modular x-ray sensor, a proximity focussed image intensifier and six CCDs coupled to the output of the image intensifier via six fiber optic tapers. The tapers are joined at the large ends to form a coplanar fiber optic taper assembly. The spatial resolution is expected to be determined by the external sensor up to the Nyquist frequency of the CCD which is (after magnification by the tapers) 3.9 1p/mm. The intended application is coronary angiography.

A Fiber-Optic Network System for PACS

This paper describes installing the first two portions of a fiber-optic based image-transmission network. The network topology is a star. The system is controlled by logical circuit switching of broadcast signals. High-speed operation is attained by two means: First, the signalling speed of the network is 144 Megabits/second. Second, wavelength multiplexing is used to separate the control signals and image-transmission signals. This paper describes the installation and integration of two arms of the network star. The arms include: the star coupler (SC), two network interface units (NIU), two interface translation units (NIU), and two units of imaging equipment (IE). Development of the system components was done separately at the Department of Radiology, University of Arizona (UofA) in the U.S.A. and at the Toshiba Medical Imaging Laboratories in Japan. The SC and NIUs were constructed by Toshiba while the ITUs and IEs were constructed by the UofA. The system integration was done at the University of Arizona by a team with members from both locations.

Prototype Performance Of A High Resolution X-Ray Imaging System For Use In Coronary Angiography

This paper describes preliminary performance data of the components of a high resolution x-ray imaging device, under development at the University of Arizona through NIH sponsorship for application in coronary angiography. The system will consist of an external modular x-ray sensor, a proximity focussed image intensifier and six CCDs coupled to the output of the image intensifier via six fiber optic tapers. The tapers are joined at the large ends to form a coplanar fiber optic taper assembly.One taper has been delivered whith distortion of less than 1.2 %.One channel of the camera and display electronics is operational. The limiting resolution of a pilotsystem, consisting of a 40 mm Gen.II image intensifier, the fiber optic taper and a CCD is 3.9 1p/mm, the Nyquist frequency of the CCD magnified by the taper.

Advanced image memory architecture

A workstation for radiographic images, known as the Arizona Viewing Console (AVC), was developed at the University of Arizona Health Sciences Center in the Department of Radiology. This workstation has been in use as a research tool to aid us in investigating how a radiologist interacts with a workstation, to determine which image processing features are required to aid the radiologist, to develop user interfaces and to support psychophysical and clinical studies. Results from these studies have show a need to increase the current image memorys available storage in order to accommodate high resolution images. The current triple-ported image memory can be allocated to store any number of images up to a combined total of 4 million pixels. Over the past couple of years, higher resolution images have become easier to generate with the advent of laser digitizers and computed radiology systems. As part of our research, a larger 32 million pixel image memory for AVC has been designed to replace the existing image memory.

Maximizing End-to-End Throughput in Image Communication Systems

We describe two systems designed and constructed in the Radiology Department of the University of Arizona.

Experimental high-speed network

Many existing local area networking protocols currently applied in medical imaging were originally designed for relatively low-speed, low-volume networking. These protocols utilize small packet sizes appropriate for text based communication. Local area networks of this type typically provide raw bandwidth under 125 MHz. These older network technologies are not optimized for the low delay, high data traffic environment of a totally digital radiology department. Some current implementations use point-to-point links when greater bandwidth is required. However, the use of point-to-point communications for a total digital radiology department network presents many disadvantages. This paper describes work on an experimental multi-access local area network called XFT. The work includes the protocol specification, and the design and implementation of network interface hardware and software. The protocol specifies the Physical and Data Link layers (OSI layers 1 & 2) for a fiber-optic based token ring providing a raw bandwidth of 500 MHz. The protocol design and implementation of the XFT interface hardware includes many features to optimize image transfer and provide flexibility for additional future enhancements which include: a modular hardware design supporting easy portability to a variety of host system buses, a versatile message buffer design providing 16 MB of memory, and the capability to extend the raw bandwidth of the network to 3.0 GHz.