Using DICOM Hanging
Protocols to Create aMulti-Discipline DICOMViewer

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1Introduction
There is no question that DICOM Hanging Protocol is an importantfeature for busy physicians. One only needs to look at the vast numberof display layout options offered by different applications, and to thespecialized views for different medical disciplines such as radiology,cardiology, mammography, dental, etc. Naturally, these specializedviewing preferences for various specialties has led to equally specializedsoftware. That is great for individual practices, but in a larger setting suchas a hospital, all this disparate software creates additional costs since eachdepartment needs its own viewer, and possibly even its own PACS. What if
there was a better, faster, and more cost-efficient way for every physician,technician, nurse, and patient to view their images easily and intuitively
using a single viewer application with all the institution’s images stored in asingle archive?
This is not a new problem. In fact, the DICOM Standards Committee
addressed this concern by defining Hanging Protocols in Supplement 60
back in 2004:“The objective [of DICOM Hanging Protocols] is for a radiologist, ora department, to be able to set up Hanging Protocols for a varietyof reading situations on one workstation, and have the capability tohave those Hanging Protocols available on several other workstations,
independent of the manufacturer.

”

More simply, doctors can “hang” their digital images on their screen, andthen save the layout and viewing preferences for reuse. It’s much morethan just a reusable display layout though; DICOM Hanging Protocols canbe used by any user with proper access rights, on any viewer, and with any
compatible set of images!
Why then, after more than a decade, is DICOM Hanging Protocol such adifficult feature to find? Truth be told, it’s difficult and complex. Realizing
the importance of a standardized way to save and reuse layouts, theDICOM Standards committee created another specification in 2008 thatis easier to implement: Structured Display (Supplement 123). This is morestraightforward because a Structured Display is based on the instances of asingle patient. It is a great way to recall the same view, share with anotherdoctor in the same practice, or even embed on a CD viewer for the patient.
However, the same distinction that makes Structured Display simpler also
makes it fall vastly short of its potential for creating an interoperable andliving digital health care ecosystem.

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An argument can also be made that Hanging Protocol was before it’stime. Its drafting was ambitious given the fact that dial-up and CRT
monitors were still on the market as viable products. In addition to therapid advancement of computer displays and networking, today’s healthcare system is also seeing a shift towards VNAs (vendor-neutral archives).
Hanging Protocols can and should be a major piece of the puzzle when
implementing a VNA for a hospital or large medical organization.
Does implementing DICOM Hanging Protocol still sound like aninsurmountable challenge that’s not worth the effort? It doesn’t have to be!
There are software development tools that can nearly eliminate the learning
curve surrounding Hanging Protocols and help you produce a shipping
product in a fraction of the time. In particular, LEADTOOLS has developeda cross-platform Medical Viewer with DICOM Hanging Protocol support
that can be used with any third-party PACS.

Using DICOM Hanging Protocols inLEADTOOLSLEADTOOLS Medical Imaging SDKs remove much of the hassle out ofimplementing DICOM Hanging Protocols. In fact, software developers
hardly have to do a thing because it’s a built-in feature of the LEADTOOLS
HTML5 Zero-Footprint Medical Viewer. This incredible viewing framework
is fully customizable, and handles everything required for both in-office andremote viewing on any workstation or device with an HTML5-compatible
web browser.
Rather than writing a script or manually selecting and assigning values totags with a DICOM Data Set creation tool, end-users and admins can create
their Hanging Protocols visually. All they need to do is click and dragimages into the study layout, and set tools preferences to their liking andclick save. The Hanging Protocol wizard will then guide the user throughthe tags used for querying the PACS and selecting images to place into
the layout. Most DICOM tags are deciphered from your current layout:
Number of cells and subcells, scrolling type, modality, body part examined,
study description, etc. Users can easily remove these pre-selected tags fora broader match, or add precise selection criteria by selecting from a listof allowable DICOM tags and manually entering values. Once saved, theuser can load the Hanging Protocol by right-clicking on the study in thesearch screen to display a context dialog with all the Hanging Protocols
compatible with the study.

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Figure 1: Right-click dialog on search results showing available Hanging Protocols to apply.

Below are just a few examples of Hanging Protocols you can create with
the LEADTOOLS Zero-footprint Medical Viewer.

Hanging Protocol Example 1: Compare Current and Prior
X-Ray
Follow-up visits are very common, therefore a way to compare the current
study with prior studies is an incredibly useful, time-saving Hanging
Protocol for physicians. Rather than searching for multiple studies andloading them one at a time into the viewer, a DICOM Hanging Protocol canfind the desired number of prior studies on the same body part and display
them side by side for proper examination.
1. Identify a patient with multiple studies taken on different dates, andload the desired image or series from the current study into the viewer.
2. Set the Study Layout to 1x2 (Rows x Columns).
3. Click the Compose Layout button to bring up the study timeline
thumbnail browser on the bottom of the screen. Find the matching
image with a date older than the current study and drag it into theempty cell.

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Figure 2: Close-up of the Study Timeline. Note the dates of each series that will aid in selecting thecorrect prior.

4. Click the Save Hanging Protocol button and proceed through thewizard, giving it a name and description on the first screen. The secondscreen, Hanging Protocol Definitions, generates the Hanging Protocol
sequence, which serves as the primary selector when choosing which
Hanging Protocols are available to the user when right-clicking on astudy. More often than not, this requires no further tweaking since it
automatically detects the Modality and Body Part Examined from theDICOM tags in the displayed images.
5. Third is the Hanging Protocol Settings dialog is the Image Sets page,
which defines how to select the images within the study. The prepopulated values here are also very reliable. However, some care should
be taken with tags like Study Description since they might be freetext fields at some practices and any variance or typo could cause amismatch. Most importantly for this example is the Time Based Image
Sets area, where you can define how priors are selected. We will takethe default of 1 prior, but it’s also possible to alter the minimum andmaximum number of priors.

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Figure 3: Configuring the Priors in the Hanging Protocol Settings dialog.

6. Finally, the Display Sets in each study layout cell can be fine-tuned aswell. This is an important step for this study since, as shown in the study
timeline, both back and side images were captured. Without defining
the Image Laterality tag with a value of B, the Hanging Protocol might
select one of the side-view images.

Figure 4: Applying the new Hanging Protocol to a patient with multiple studies.

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6Hanging Protocol Example 2: Multiple MRI Priors
DICOM Hanging Protocols have their home outside of radiology as well.
For example, MRI studies often require follow-up visits as well to check on
the progression of a condition. Hanging Protocols are flexible enough bothto pick and display a variable number of priors. For example, the same
Hanging Protocol could be used on a patient with 5 studies over the courseof many years and a patient with only 3 studies. In each case, it will startat whichever study was selected as the current and go back in time finding
the studies with matching criteria, as shown below:

Figure 5: Using a Hanging Protocol with up to 5 priors for an MRI patient with many prior studies.

Figure 6: Same Hanging Protocol used on the same patient, but selecting an older “current” study.
From that point in time, there are only 2 priors instead of 4.

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Hanging Protocol Example 3: Side-by-Side Mammography
LayoutAnother medical discipline that can benefit greatly from DICOM Hanging
protocols is mammography. These studies are very routine and for nearly
every patient capture the same set of images. This means that doctors will
similarly want to view these four images the same way every time.
However, sometimes images might need to be re-taken or are simply doneout of order, so a traditional grid view for the series won’t guarantee thecorrect placement. Additionally, most physicians have additional viewing
preferences that stray from the industry standard of center-aligned images
and wish to see the images justified and mirrored against each other.
1. Find any MG study with four images and load it into the viewer. The
images are often placed into a single series, but it will also work if thestudy has four series with one image each.
2. Set the Study Layout to 2x2.
3. Click the Compose Layout button and drag the images into theirappropriate cells. In the case of a 4-image series, you will actually be
dragging the same series into each of the four cells.

Figure 7: Composing the Hanging Protocol layout by clicking and dragging from the Study
Timeline.

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84. Scroll the images in each cell as desired so that the matching left andright images and view positions align with each other as if they weremirrored.
5. Now set the image justification to align the right cells to the left marginand vice versa, finalizing the mirrored layout.
6. Now we are ready to save the Hanging Protocol. Name it on step 1 andaccept the defaults for step 2 to arrive at the Hanging Protocol Image
Sets definition page. Some of these automatically detected selectors
should be removed or edited, especially Image Laterality since it iscurrently only set to R. Deleting it will most likely be sufficient due
to the nature of mammography captures, but we will set its value to“R\L” just to be safe in the unlikely event of an image captured from adifferent laterality.
7. The real magic happens for this layout on the final Display Sets page.
Use the drop-down box to ensure that each corner of the layout isproperly filtering by the desired View Position and Image Laterality.
Without filtering these images strictly, duplicate images will appear, andeach of the cells would be scrollable. Instead, the strict filtering restricts
each cell to display only one image out of a possible 4 images in theseries.

Figure 8: Defining the Display Sets (Step 4) with the Hanging Protocol Settings Dialog.

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9Figure 9: Using the new MG Hanging Protocol on another patient’s images.

Hanging Protocol Example 4: Dental FMX
The dental market has some of the most specialized image layouts around.
Due to the curvature of the mouth, many images are taken from various
angles to give the dentists and hygienists the full picture on a 2D screen.
A full mouth series of x-rays (FMX) does not follow the typical grid layout
favored in radiology, but one that helps visualize and identify each toothand their location in the mouth.
The LEADTOOLS Medical Web Viewer is also able to display images ina non-grid layout. Precise layouts can be drawn and then saved to theserver for re-use. To make things even easier, LEADTOOLS already includes
built-in and customizable templates for many popular layouts, including
dental FMX 18 and FMX 20. Here are the steps for creating a dental FMX 18
hanging protocol:
1. Find a dental patient with an FMX 18 series and load it into the viewer.
2. Click the Study Layout button and select “FMX 18 Instance” from thetemplates drop down box.
3. You will now see the blank FMX 18 layout with non-grid cells.
4. Click Compose Layout to bring up the study timeline. Just as was donein the mammography study example, click and drag the same series into
each cell, then scroll so that the correct instance is displayed in eachcell.

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Figure 10: Dragging images from the study timeline into the non-grid FMX 18 Instance layout
template.

5. Click on Save Hanging Protocol, give it a name, and proceed to step #3
on the Hanging Protocol Settings dialog.
6. Since we are setting up this Hanging Protocol for a specific device thatwill save the FMX 18 images in the same order, we can reliably trust that
the Instance Number tag can be used to identify which image goes ineach cell. Therefore, in step 3, delete the Study Description and Image
Laterality tags and click Next.
7. On the Display Sets pane in step 4, delete the Image Laterality Tag fromall display sets with the Delete Similar Filter Operations button. Clickthe Add Filter Operation button and use the dialogs to select and add
Instance Number tag.
8. Click the Clone Filter Operation button, which will apply the selectedfilter operation (Instance Number in this case) to the remaining 17
display sets. This only clones the tag, and will check each cell’s currently
displayed image to get the value to apply in the filter operation, which
will result in properly matched images when studies are loaded with thishanging protocol.

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Figure 11: Applying the FMX 18 Instance to a study with a full set of FMX 18 dental images.

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12Conclusion
The long history of implementation difficulties, lagging supportive
technology, and vendors not working together in an interoperable
environment have dragged along the realization of true DICOM Hanging
Protocol support. The market is ripe and demand is growing for thisforgotten gem of the DICOM Specifications. Software developers keenon creating and integrating with VNAs can use medical imaging SDKs like
LEADTOOLS to capture the market on both ends of the spectrum. Its
HTML5 Zero-footprint Medical Viewer is a ready-built solution and canbe a go-to viewer for any desktop or mobile platform and includes both
DICOM Hanging Protocol support as well as all the other viewing tools
medical professionals need. LEADTOOLS also includes all the DICOM
communication and PACS support needed to easily build a VNA from theground up or to create a central hub for integrating any existing third-party
archive.
LEADTOOLS offers an incredible value with its comprehensive family oftoolkits for medical, document, multimedia, and raster imaging. For more
information on how LEAD Technologies can image-enable applications andboost ROI, visit www.leadtools.com to download a free evaluation, or give
us a call at +1-704-332-5532.

Additional Information
Read more about LEADTOOLS DICOM Hanging Protocol SDK
Watch a video overview of the LEADTOOLS DICOM Hanging Protocol SDK

2017 LEAD Technologies, Inc.

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Sales: +1(704) 332-5532
sales@leadtools.com
Support: +1(704) 372-9681
support@leadtools.com

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About LEAD TechnologiesWith a rich history of over 26 years, LEAD has established itself as the world’s leading
provider of software development toolkits for document, medical, multimedia, raster,and vector imaging. LEAD’s flagship product, LEADTOOLS, holds the top position in
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2017 LEAD Technologies, Inc.

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