Fast web queries but slow DICOM query access

[orr...@gmail.com]

Hi Sébiastien,

thank you for a great program. I use it as an intermediary database for images coming from CDs, examples, demo data, etc..

However I have hit a problem recently. As the number of studies reached above 70 the DICOM queries are very slow, i.e. I have to wait for something like 1,5-2 minutes to get the query results on my viewer workstation. During this time the server computer with orthanc running is very busy, accessing the hard drive constantly.

On the contrary, the web access using a firefox browser is almost instant without any noticeable server activity.

Once the query results are displayed in my workstation software the study transfer proceeds at normal speed, i.e. there is no difference to speed of the transfer initiated from the web browser.

I am no programmer, but it looks to me that the web access uses some kind of index of studies, while the DICOM query mechanism results apparently in a full scan of every file the database.

Do you have any plans to relieve this situation?

Thank you very much again.

Pavel

[orr...@gmail.com]

I have forgot to include my configuration: Qrthanc 0.7.3 running on Windows XP 32-bit. P.

[Sébastien Jodogne]

Hello Pavel,

The asymmetry you noticed in the running times indeed looks like a bug. For me to be able to spot the problem, what is the DICOM client that you use?

You say you have about 70 studies, but how many DICOM instances are stored in your Orthanc database? This information can be retrieved by accessing the "http://localhost:8042/statistics" URL.

TIA,

Sébastien-

[orr...@gmail.com]

Hi Sébastien,

huh, the database really grew up last few days, this is the statistics as of today:

{

   "CountInstances" : 103686,

   "CountPatients" : 124,

   "CountSeries" : 1963,

   "CountStudies" : 193,

   "TotalDiskSize" : "46639065892",

   "TotalDiskSizeMB" : 44478,

   "TotalUncompressedSize" : "46639065892",

   "TotalUncompressedSizeMB" : 44478

}

I can probably remove some studies, but as I said previously, the web access speed is fully satisfactory, only the DICOM query mechanism is slow.

The DICOM client I use is called TomoCon Workstation (www.tatramed.sk). Unfortunately they do not provide a free download. However I use it to access our other PACS servers, including the main one (with patient data for 9 years of work), without any problems.

I can try to use other clients as well - as a test, do you recommend any free ones that are known to work well with Orthanc?

Thank you again.

Pavel

[Sébastien Jodogne]

Hello,

This is great to know that Orthanc scales well enough to store more than 100,000 DICOM instances (at least as far as the Web access is concerned)!

If you restart Orthanc with the "--verbose" command-line option, the content of the incoming C-Find DICOM requests will be displayed in the log. Please could you send us the content of this log? It should contain interesting information about the behavior of TomoCon Workstation.

As you noticed, it would also be useful to check whether the problem also appears in other DICOM viewers. Here is the list of open-source viewers that have been reported to work together with Orthanc:

• Ginkgo CADx (probably the easiest to give a try): http://ginkgo-cadx.com/en/
• medInria: http://med.inria.fr/
• 3D Slicer: http://www.slicer.org/
• OsiriX (only for OS X): http://www.osirix-viewer.com/
  

Sébastien-

[orr...@gmail.com]

hi,

so I checked with findscu from the OFFIS DCMTK toolkit and that takes only 6 seconds to check all the patient names.

I will try to get the log file of the Tomocon query and will report tomorrow.

P.

[Sébastien Jodogne]

Fine. This clearly indicates that Tomocon asks Orthanc to return a field that is not considered as one of the so-called "MainDicomTags": Such fields are not indexed in the SQLite database, so that Orthanc has to open all the DICOM instances one by one to extract the value of these fields.

The log file should indicate what is the problematic field. A patch specific to Tomocon could then be introduced in the Orthanc source code.

Sébastien-

[orr...@gmail.com]

Hi Sébastien,

well I have run the Tomocon query again with the --verbose option on the orthanc. But the time is down to approx. 10 seconds..! Could it be that the orthanc database needs some time to recover after a lot of store requests? Perhaps I was just unlucky to notice the time delay during the normal work day, when there was greater chance to have the database modified.

Looking at the log (file attached) the Tomocon query runs at the STUDY level. So I re-run the search with the findscu on the STUDY level as well and now it gives the same time - 11 seconds.

But then again the web page load is only 2 seconds and search is instant.. (visually and according to Chrome developer tools).

To put things into perspective Tomocon search against commercial workstation (Philips) with 3 times as many studies is 2 seconds as well. But this uses a dedicated database. Maybe the SQLite is too slow for this many instances..

I will try some of the programs you have provided and let you know.

P.

[orr...@gmail.com]

Hi Sébastien,

Gingko CADx and medInria take about the same time to make a query as the Tomocon software - approx. 10-11 seconds. 3D slicer was much slower, but it was really strange to configure, so maybe I made some mistakes.

Thanks.

P.