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Bolt on Performance Tools for your PACS systems. Get that extra hidden network horsepower by using the right tools.


Abstract: This is to report the discovery of an insidious, but repairable impediment to the efficient flow if DICOM images in our PACS systems. It was found that the network IP frames were mysteriously being set to 590 bytes as compared to the upper limit of 1518 bytes. Exempla Network and PACS IT staffs were able to engineer a solution that brought them a 80 + percent improvement in PACS image speed from the Dicom servers to the Radiologist workstations.
The intent of this article is to be of benefit to others in order to increase PACS image delivery speeds and efficiency of Administrative and Radiology personnel, thereby improving patient satisfaction, care, and safety.

Introduction:  At SCHLS – Sisters of Charity Of Leavenworth a 11 hospital network in several states in the US, they are always striving to improve their operating efficiency and lower costs. The IT division in their Denver Region has implemented impressive speed improvements through innovative thinking, select registry tweaks coupled with the industry standard, proactive PACS monitoring tool, – DICOMetrix. SCLHS is using several versions of the DICOMetrix software’s from the 5, 10, 25 channel to the 125 channel and the Radiologist workstation dual channel version. So that all levels of personnel can see how the PACS system is operating and receive slowdown alerts, they also have the Web DES system installed and operating.

Technical Report:
SCLHS using DICOMetrix to provide some visual and analytical methods to measure images and network traffic arriving at a Radiologists workstation.  In a collaborative effort, PACS and Network IT Analysts are able to determine two separate settings that can be made in a Dicom Image server registry that will allow the 590 byte packet sizes to grow to 1314 bytes.  By setting these registry setting manually, the PACS DICOM server’s Image Download speed improved 87.5%
 With help from Microsoft Technical support, changes were made to the Dicom Server’s registry keys,   By setting the frame sizing up, the frame sizes grew to 1314 bytes and combined with the windowing setting,  a total of 87.5% increase in network speed was established.  The same set of images were used in each measurement - a 2,313 image CT scan downloaded from a HP Pro-liant DL380 G3 server using a Fuji Synapse PACS system and running on a Windows 2000 Server platform. To make sure there were no anomalies in the measurements, three separate measurements were made after each registry change. The measured values at each stage of the process showing the images per second (IPS) average, as displayed in the DICOMetrix GUI shown below:

To begin, the IPS was measured as the images were received at the workstation; no changes to the registry were made:  ( Average shown in 15 Min Gauge = 13.6 Images per second

Microsoft suggested that the Windowing size be set to 65,535.  After incorporating their suggestion, another reboot and loading the same image set, a 23.18% increase in speed was shown ( 25.5 – 20.7  = ‘4.8’ IPS or 4.8 / 20.7 = ’23.18 %) In order to show all three measurements and all three tests, the DICOMetrix Graph feature was utilized and the slider was adjusted so that the entire 3 hours of measurements could be viewed simultaneously, as shown below:

     The calculations are -  ( 25.5 – 13.6 =  11.9 IPS  or  11.9 / 13.6 =  87.5 % Overall increase in Speed) 


Below is a screen shot of the three studies using a cool feature of  DICOMetrix called the mini-mode. It is a symbiotic view of their Gauge and graph superimposed onto one display:


  In conclusion, outstanding results were achieved with the 2 registry changes. Immediate changes to all system wide servers were made and they now enjoy the improved image speed performance system wide.

 Regarding the improvements in speed and monitoring that Exempla has experienced, Tamara Havenhill-Jacobs, Manager of Exempla’s Imaging Information Systems group has stated, “Due to the use the DICOMetrix products, we are now able to see, in real time, how this tool can help us pro-actively measure and easily share our PACS systems speed analysis findings with other IT and Medical Imaging staff members. We knew things were slow at times but we had no method or tool of which to measure and visualize our PACS systems speed until now.  We are testing the DICOMetrix server software on our PACS Test server to begin base lining our new system speeds as we roll out these registry changes to all our Dicom servers enterprise wide.  We also look forward to base lining the speeds of the incoming modalities so we know what a ‘normal’ speed is when the network is healthy. “

For specific information on the registry changes, please contact -  Michael Lunsford   - Spectrum PACS Company at mike@spectrumpacs.com

For trial versions of DICOMetrix please email us at Mike@SpectrumPACS.com

For more detailed information on DICOMetrix, please visit their Web site at – http://www.DICOMetrix.com