wiki:DicomBrowserDemo

DICOM files come in batches of many files with related metadata in each. We have written a browser that displays an organized summary of this metadata in a tree and also displays a preview of some image files.

This browser is also small enough to be a manageable introduction to wxPython. It runs under OS X, Linux and Windows provided wxPython is installed.

The browser does just a few things. It allows one to select a directory containing DICOM files, it reads the metadata in each file while providing feedback, and then it displays the files organized in a tree. Finally, when the user chooses a file (or hits cancel), it closes and prints out the user's selection.

In order to run it, you'll need to install the pydicom library.

To run it, cd to the directory where main.py lives and type python main.py.

If you don't have any DICOM files with which to test, you can download some from our SVN repository (see the siemens_dicom_export directory): https://scion.duhs.duke.edu/svn/sample_data

There are three versions, each an improvement on the previous. They live in the orphans SVN repository (https://scion.duhs.duke.edu/svn/orphans/) in the directory philip.

The simple version is in orphans/philip/dicom_browser-1.0/. This version doesn't offer image preview. It also assumes that all DICOM files contain a Siemens-specific tag.

A more sophisticated version is in orphans/philip/dicom_browser-2.0/. This offers image previewing (for certain files, notably the 55* series in our sample data). It differentiates between Siemens and non-Siemens files, and it makes the dialog easy to subclass for coders who want to change how the dialog constructs the tree item description string.

The most recent version in orphans/philip/dicom_browser-2.1/ adds optional multi-select capability and a subclass-friendly dialog class method that can filter files out of the tree.

The Files

  • browser_ui.wxg is the wxGlade file that describes the user interface. wxGlade generates gui_browser.py for me.
  • dicom_browser.py subclasses the dialog created in gui_browser.py.
  • util_dicom.py contains the code that talks to the pydicom library and generates a list of DICOM files for the dialog box.
  • util_dicom_generic.py contains the DicomFile class which is a generic container for DICOM files.
  • util_dicom_siemens.py contains a Siemens-specific subclass of the DicomFile class.
  • main.py creates a dummy main window that launches the dialog.

Technical Notes

  • It might be tempting to combine dicom_browser.py and util_dicom.py, but separating them is useful. It allows the latter to be used with a dependency on wx. It can be used, for example, on a server to generate a DICOM file list for a Web application. In that context a wx dependency would be a headache.

  • Similarly, we want to be careful with integrating dicom_browser.py with our library of wx utilities since it has a depedency on the pydicom library. We can add it to the library but it should remain a separate file so that only applications that import dicom_browser will have a dependency on pydicom. The rest of the files in the wx utilities library will remain free of this depedency.

  • wxPython code is always a little awkward because Python and wxWidgets follow different naming conventions. Python naming convention uses lower_case_variables_names while wx uses TitleCaps. This results from the fact that wxWidgets is written in C++ and wxPython is a thin, auto-generated wrapper around it. In practice, it's unusual to find a Python library that doesn't follow Python's naming conventions.

In our code we've introduced a third style (from Java, I think) for naming GUI controls and event handlers which is firstLetterLowerThenUpper (e.g. the dialog has an event handler called onTreeItemActivated()).

Using two different naming conventions is confusing enough; I do not recommend following our example and introducing a third. In this code, I used firstLetterLowerThenUpper only to be consistent with our existing libraries.

  • The function util_dicom.get_files() is a Python generator which is something you might not be familiar with. There's a lot of tutorials online about generators, all of which I find much harder to grasp than the actual code. Maybe it's just me! Here's one such article: http://www.ibm.com/developerworks/library/l-pycon.html
Last modified 9 years ago Last modified on Nov 5, 2010, 2:34:13 PM