DICOM Special Cases

Sometimes the interpretation of DICOM data is unequivocal and PMOD may organize the images in an unexpected manner. To solve this situation SPECIAL CASEs can be defined which impose a specific interpretation of data from a certain Manufacturer model and Software version.

To create a new special case select Add new case, specify a name, and then select the appropriate behavior from the Case list. The requested information can be entered manually, but it is easier and safer to select Get from file, browse to the directory where the data resides, and select the appropriate series. PMOD reads the required information from the DICOM attributes and fills it into the Manufacturer, the Manufacturer model and Software version fields. Note that * can be used to indicate applicability for all possible strings, while an empty field requires that information is also empty in the corresponding DICOM field.

To transfer these definitions between systems there is an Export button for saving the special cases, and Import button for loading them.

The Case selections are listed below with some example systems. However, the need and applicability of these special cases may depend on specific software versions of the originating system.

• Non identical images times for single volume: Select this option if the slices of a single volume are interpreted as separate frames in a dynamic series (e.g. series with no positioning information like SC).
• Multivolume (sort by volume times): To be used when the time sorting of a dynamic series is wrong (Siemens Sonata, Siemens Symbia).
• Multivolume (sort by slice position): Another situation where the time sorting of dynamic volume data is wrong (Siemens Evolution EBCT scanner, GE Discovery LS, GE Discovery HR, GE Signa Excite).
• Multivolume MR (sort by trigger times): A third situation with wrong time sorting (GE Signa Genesis).
• PET frame times in sec (instead of ms): To be applied if the acquisition times presented in PMOD for PET objects are 1000 times too small.
• Volume SC: For situations when a screen capture series representing a volume is displayed as a big number of separate series (GE Advantage Windows, GE Discovery HR, Siemens Somatom Emotion Duo).
• Wrong slice spacing (use slice thickness): Try this case in case the slice thickness presented in PMOD differs from what you expected (some GE Xeleris versions).
• Wrong Image Index in PET objects: Some PET/CT systems do not construct the Image Index (0054,1330) as specified in Dicom PS3.3 paragraph C.8.9.4.1.9. As a result PET images may be sorted wrongly (GE Discovery LS via Xeleris).
• Wrong frame reference time (use acquisition time): Instead of the PET specific element 0054,1300 (Frame Reference Time) the general element 0008,0032 (Acquisition Time) is used to determine frame start and end times. If the acquisition time element is present and it is filled with the frame start time this usually solves the problem. (Philips, Protocol Guardian Bod; SUINSA animal PET system).
• Reference time at frame half (calc from duration): The default behavior for PMOD is to calculate frame start and end times based on frame reference time and duration assuming that the reference time points to frame start. This special case uses the assumption that the reference time is at frame mid-time. (Philips)
• Times start not at zero (move to zero): This case was introduced for Philips data that had a substantial offset in the 0054,1300 Frame Reference Time. It just offsets the times so the first frame starts at 0. It does the same as Set acquisition start time to zero in the loading parameters dialog.
• Wrong image class unique id: This special case is to allow PMOD reading images that have wrong DICOM object class specified in the file.
• Use acquisition times for frame times: This special case is instructs PMOD to use the acquisition time instead of the content time when determining the frame times for single slice objects.

Note: The DICOM server will use these case definitions when receiving the images and storing them in the database. So if series are not correctly entered into the database, please export the data and define a suitable Case using the Get from file facility. Then, delete the database entry, restart the DICOM server, and transfer the series again.