HTML5 DICOM viewer

Infomedica, provider of integrated RIS/PACS solutions in Croatia and region, is anouncing first HTML5 DICOM viewer beta release.

  

HTML5 DICOM concept

  

Infomedica, provider of integrated RIS/PACS solutions in Croatia and region, is anouncing concept of plugin-less DICOM web viewer.

  

1.     Introduction

  

World of RIS and PACS has, already for more then 10 years, been enriched with web browser access to RIS data and PACS images. After all, RIS/PACS systems are still advertised as „web access from anywhere“ systems. While web access to RIS data was not an issuse, access to PACS images was always playground of different technological approaches and interesting ideas. The reason was 16 bit-ness of DICOM images from PACS archives.

Namely, web browser are not capable of displaying 16 bit gray images (65536 gray values), but only 8 bit gray images (256 gray values), because of graphical hardware limitations. Therefore, well known transformation of 16 bit gray images to 8 bit gray images had to be taken into account – windowing/leveling.

Vendors have taken advantage of different technologies (Java from Sun, ActiveX and Silverlight from Microsoft, Flash from Adobe) to achieve PACS workstation usability in web browser. We call such concepts „plugin concepts“, because web browser has to download DICOM viewer plugin and run it inside web browser.

We want to propose real „plugin-less“ concept where image rendering and windowing/levelling is done directly in browser without downloading anything except HTML code. We achieved that by using advanced features of the new HTML5 standard. Idea is to have access to PACS anywhere, anytime from web browser.

  

2.     HTML5

  

HTML stands for „HyperText Markup Language“ which is used to display content on web pages. It is devloped by World Wide Web Consortium (W3C). HTML is currently in 4.01 version. Next release of HTML standard will be HTML5 standard. HTML5 brings some interesting new features which developers round the world have already recognized as a new platform for software development. Among different new features we will consider here only those that we have used to build „plugin less“ DICOM web viewer:

  

·        Canvas element – the new tag in HTML5 standard which is used for immediate 2D drawing with related Canvas 2D API

·        Web workers – new API which provide means to run scripts in web browser background thread (multithreading Javascript)

·        Offline storage and Web SQL – new API for storing data in web browser for offline use

·        Drag and drop functionality for intuitive user interface

  

3.     Concept

  

During february 2010 we have sucesfully displayed first DICOM image in browser. In the next few days we have already had full windowing/levelling. We continued with development of new software and here we can present concept.

  

  

Image 1. Concept of DICOM web viewer

  

Server side

  

First of all, we need PACS archive which supports C-GET or C-MOVE of DICOM images. Second item on server side is web server application, which is basically WADO (Web Access to DICOM Persistent Objects) server, but slightly customized for this demonstration. WADO server loads images from PACS and sends them over the network to web browser. It is important to notice that WADO server sends 16 bit DICOM data over the network.

  

Web browser (client side)

  

When user logs to web PACS interface and selects image serie for loading, web application starts loading images from PACS and transferring them to browser. One of the first thing we wanted to achieve after windowing/levelling is asynchrounous image loading. Usually, if one wants to perform parallel activites in web browser, one must use unhandy Javascript timers. HTML5, like we already noticed, brought to us „Web workers“, therefore user can work on images while they are loading from network. DICOM module is javascript engine that transforms 16 bit DICOM image to 8 bit – performing window/level.

  

Testing

  

System was tested in major browsers: Firefox, Chrome, Opera, Safari and Safari mobile for iPad, and on wide range of computer configurations. We still wait for official release of Internet Explorer 9. Window/level transformation performance was measured. One W/L change was measured in miliseconds. After few optimization techniques we get next results:

  

Image 2. Window/level performance in different browsers (miliseconds)

  

As we can see Google Chrome is definitely fastest browser, but all other browsers provide fluent interaction as well. Our testing computer was Windows XP Intel Pentium Core2Duo 2.13 GHz with 2GB RAM for Chrome, Firefox and Opera. For Safari we used Mac Leopard 10.5.8 Mac Pro 2 x 2.8 GHz Quad Core Intel Xeon with 2GB RAM. Just for fun we tested system on old HP laptop with Windows XP and Intel Pentium M 1.60 GHz and 512 RAM – we got 30ms for W/L on Chrome and system worked really fluent.

  

4.     Demonstrations

  

In this section we will show proof-of-concept videos.

Google Chrome and Mozilla Firefox video:

  

  

5.     Future

  

First release

  

First HTML5 viewer release is scheduled for the end of 2010 or sooner. We expect to have both integrated and stand-alone viewer. We would like to bring stable and fast web viewer, which runs seamesly on all browsers.

  

Tablets

  

Our focus is on tablet market too. We see tablets as important devices in healtcare, especially in radiology field. There, we see potential for our HTML5 DICOM viewer. At this moment we have adopted our HTML5 viewer for Webkit based browsers (Android and iPad tablets).

  

Offline storage

  

Already mentioned new feature of HTML5 standard will help developers to build web applications that hold downloaded data even when users are offline. We will include this feature in our concept, so that viewer holds session data (images) for the offline use.

  

Source : http://www.infomedica.hr/html5/