One of the biggest problems in radiology when you consider enterprise and multi-enterprise image distribution, becomes managing workflow and data flow," says Gary Wendt, M.D., M.B.A., vice chairman of informatics for the University of Wisconsin department of radiology in Madison. Images generated on any number of modality scanners must be routed to specific workstations for post-processing procedures and to the clinicians who require that information to provide appropriate patient care.

For example, if a spinal imaging study is acquired, will it be read by an orthopedic surgeon, neurosurgeon or other specialist, and where will that clinician be located physically within the enterprise to view the post-processed image data set?

Wendt uses a McKesson Horizon system with a central common RAID (redundant array of independent disks) repository on-demand system that is integrated via their EMR (electronic medical record) system to clinical data maintained by their HIS/RIS capabilities.

Warren S. Edwards, Ph.D., vice president of engineering at McKesson Medical Imaging stresses the importance of a logically centralized architecture where all of the data that comes into the system is stored using a high availability configuration, with no single point of failure. They recommend use of a WAN (Wide Area Network) infrastructure with built-in redundancy in two or more database servers.

Coupling distribution challenges with the massive volume of image data sets produced by today's multislice scanners requires careful allocation of network resources.

"With some of the CTAs [computed tomography angiograms], you can have 1,000 to 2,000 images, and you can be pushing a Gigabyte of data. If it's sent into the PACS, and it's brought up once or twice in the workstation, you multiply your total data flow by two or three," continues Wendt. "If you have an auto-routing situation, and you push that data set to 30 workstations, you've multiplied your traffic over the network so that you're now pushing 30 Gig over your network."

John C. Weiser, Ph.D., diagnostic imaging physicist for Xtria Healthcare in Frederick, Md., explains that a standard chest x-ray file would contain about 10 megabytes per image. However, with digital mammography, the typical image file is closer to 40 megabytes. He describes one network configuration solution involves use of a VLAN (virtual local area network), to remove imaging data flow from their primary IT network, thereby providing its own dedicated bandwidth.

In addition to their VLAN network design, Weiser explains that the Lahey Clinic (Boston) utilizes three levels of image compression between the server and the workstation. Lossless compression is used for primary diagnostic functions. In that scenario, the image remains mathematically unchanged once it has been decompressed. They use lossy compressions for clinical compression that provides images to referring physician offices, and deep compression is used for archiving image data sets. Most clinicians would find it difficult to discern which images had undergone lossy or lossless compression.

Another issue involves adherence to HIPAA regulations for patient privacy. Peter McClennen, general manager of global market for GE Medical Systems Information Technology, explains that Centricity Enterprise Web used as a data and image distribution system requires password access. If the user is within the hospital, they use a workstation located on a secured network. Outside the institution, they access the network through a VPN (virtual private network) or SSL (secure socket layer).


MORE DIAGNOSTIC INFO

Current workstations leverage computing power to offer advanced applications that benefit clinical management of patients who often exhibit complex disease processes.

Silicon Graphics, Inc. (SGI) has worked for many years with OEMs to provide components that they could integrate into their various modalities. Volumetric visualization is a trend that they see in enhanced workstation capabilities.

Michael Brown, SGI marketing team manager for advanced graphics explains that they can take the entire volume of data from a CT scan, enable the clinician to view images from whatever angle they prefer, manipulate various levels of transparency to see through certain structures, or even allow them to be time varying so that they can see a heart beating or muscles contracting.

The Advantage Workstation from GEMS offers software analysis tools that permit clinicians to accomplish 3D renderings of the original data sets. At RSNA 2003, GEMS launched several new post-processing capabilities including AutoBone for CT imaging studies. With a single click of the mouse, the user can remove all bone from the image data set, to enhance visualization of critical structures that would otherwise be obscured. The CardEP function provides a geometric model to assist in planning for electro-physiological ablation procedures. And the OneTouch protocol offers tight synchronization between the Advantage Workstation, CT scanner and PACS, according to GEMS general manager of Advantage Workstation and Clinical software, Jennifer Dible.

The Leonardo workstation was launched by Siemens Medical Solutions a few years ago, but they have since added new functionality. Rik Primo, manager of marketing and strategic relationships for Siemens, explains that because multislice scans are becoming the industry standard, they have incorporated advanced 3D reconstructions into the core capabilities for Leonardo. Once the MR or CT scan is obtained, images are presented in 3D format, so that the clinician can scroll through, select an area of interest, and immediately see the corresponding 2D slices. For example, if a neurosurgeon were interested in the pituitary gland, the 3D rendering would show the entire brain, and the physician could select the area of the eyes, and begin to see the cross-section of the pituitary gland.

Chris DeAngelo, RTR/CT, the CT coordinator for Alamance Regional Medical Center in Burlington, N.C., is using two Leonardo workstations for both CT and MRI to post-process their digital images. Because their department is not yet filmless, the capability of this workstation enables them to perform functions they would otherwise be unable to execute.

"InSpace is a Siemens software package that enables the user to perform quick volume-rendered 3D images to correlate with conventional CT images," DeAngelo explains. "Then the radiologist can visualize four different images in four different planes: axial, sagittal, coronal and the 3D image in the bottom right hand corner." In addition they can scroll through each individually or simultaneously.

For radiation therapy applications, NOMOS Corp. offers the CORVUS planning workstation that can be connected to the IT network from the institution's various imaging modalities. Rick Chevalier, the product manager for planning systems, explains that CORVUS is capable of fusing MRI to CT images and PET (positron emission tomography) to CT images to assist in defining tumor mass for delivery of IMRT (intensity modulated radiation therapy).

Dan Pavord, M.S., director of radiation oncology at Western Pennsylvania Hospital in Pittsburgh, is using the CORVUS system. He describes a smooth deployment of this system on their existing network, involving the establishment of IP addresses and utilization of DICOM parameters.

One slight problem that required additional consideration was the fact that PET imaging studies use a data format known as DICOM-nucmed which is incompatible with either CT or MR DICOM since PET studies are rendered in 3D. With some image conversion, they have developed the methodology to fuse MR/CT and CT/PET image data sets.

Additionally, they use their network to send a completed treatment plan to the Report and Verify system to insure that all of the settings on the linear accelerator match the plan before the radiation beam is activated.

AMICAS in Boston has released their LightBeam web-based diagnostic workstation. Employing an on-demand viewing approach means that no pre-fetch is required.

"LightBeam is a software-only thin client workstation, so in contrast with traditional PACS approaches, the radiologist or advanced clinician doesn't have to go to a specific workstation to accomplish their tasks," says Brad Levin, director of strategic marketing for AMICAS. So long as there are a sufficient number of licenses available (which is tracked locally on the server), physicians across the enterprise can access the functions of a diagnostic workstation using authenticated access.

Planar Systems Inc. offers three different workstation configurations depending on the needs of the particular users. The software application known as Cxtra works across all platforms and provides consistent DICOM calibration.

"This means that an IT person doesn't have to learn a number of different ways to calibrate their different displays," explains Steve Flieder, vice president and general manager of the medical business unit. Additionally CXtra offers remote monitoring of all workstations to review calibration, brightness and 70 other performance parameters. CXtra proactively notifies the IT professional of any problems using SNMP (simple network management protocol) function. "Because of SNMP, it can be set to notify via email, voice mail, send a page or whatever way the IT person prefers."

A final challenge with maintenance of image data files is the importance of providing access to stored data over many years. 3Ware works with major vendors to provide Serial ATA, low cost storage utilizing RAID so that data could be reconstructed easily in the event of a drive failure.

"The alternative technology that was available is called SCSI, which is expensive," explains 3ware's vice president of marketing Barbara Murphy. "Serial ATA allows you to buy inexpensive drives with this interface. In the event of a drive failure, the IT person can come, replace that drive, and then we rebuild that data from another drive."


CONCLUSION

With all of the capabilities of today's workstations, appropriate network allocation to provide essential connectivity and function remains critical to the smooth flow of image data sets and other information throughout the enterprise.