WEB PLATFORM TO SUPPORT THE SHARE AND REMOTE

ACCESS TO MEDICAL IMAGES

Sérgio Lima, Natércia Sousa

IEETA – University of Aveiro, Aveiro, Portugal

Carlos Costa, Augusto Silva

IEETA – University of Aveiro, Aveiro, Portugal

Keywords: Medical Images, PACS, DICOM, WADO, WebServices, Image Network.

Abstract: The production of digital medical images has been growing in every healthcare institution, representing

nowadays one the most valuable tools supporting the medical decision process and treatment procedures.

One of the most important advantages of these digital systems is to simplify the widespread sharing and

remote access of medical data between healthcare institutions. However, due to security and performance

issues, the usage of these software packages has been restricted to Intranets. In general, the storage and

transmission of digital medical image is based on the international DICOM standard and PACS systems.

This paper analyses the traditional PACS communication limitations that contribute to their reduced usage

in the Internet. It is also proposed an architecture, based on Webservices and encapsulation of DICOM

objects in HTTP, to enable trans-institutional medical data transfers.

1 INTRODUCTION

It is widely known the enormous importance that IT

technologies have been acquiring in all sectors, and

the health services field is not immune to that

reality. Effectively, a vanguard clinical service,

properly equipped to administrate medical care in

quantity and, most of all, in quality, cannot neglect a

proper investment in IT, i.e. "in information systems

and telematic infra-structures capable of assuring a

set of activities related to medical care".

Along with the evolution of the information

systems, it also grows the medical applications

needs of computational processing, i.e. the

management of patient demographics, as well as all

the inherent process of diagnostic and/or medical

intervention (acquisition, processing, transmission

and storage). It is here that utilization of the most

advanced multimedia technologies enters, making

perfectly viable the co-existence of text elements

and digital information that characterizes medical

images formats. The main idea will be, therefore, to

improve the acquisition, processing, transmission

and storage of medical images, making trustworthy

the diagnosis, improve the staff motivation, and still

achieve a reduction in global costs.

2 DICOM STANDARD AND PACS

SYSTEMS

With the increase in the use of electronic medical

equipments and consequent amount of digital

information, was necessary to develop a set of

recommendations and base lines responsible for the

inter-operability of medical equipment provided by

different suppliers. It became essential the creation

and adoption of a series of standards such as the

DICOM (Digital Imaging and Communications in

Medicine), developed by the consortium ACR-

NEMA. It broadly defines the formats and processes

of storage and transmission in medical imaging.

Moreover, it not only promoted the data

communication but also the development and

expansion of the storage systems, converging to

hardware and software platforms usually designated

as PACS (Picture Archiving and Communication

Systems) (Huang, 2004). Finally, it also defines

291

Lima S., Sousa N., Costa C. and Silva A. (2007).

WEB PLATFORM TO SUPPORT THE SHARE AND REMOTE ACCESS TO MEDICAL IMAGES.

In Proceedings of the Ninth International Conference on Enterprise Information Systems - SAIC, pages 291-294

DOI: 10.5220/0002392202910294

 SciTePress

interfaces with other medical information systems,

namely RIS (Radiology Information Systems) and

HIS (Healthcare Information Systems).

As a summary, we can say that DICOM protocol

covers the following aspects (Philips, 1997):

 the commands syntax and associated data, so

different devices can communicate;

 the file service syntax with respect to format

and directory structure necessary;

 the operations in networked environments

using, the existing standards (TCP/IP, …);

 support for new emerging services resulting

from new medical image applications.

DICOM is now a well established standard in the

medical community. Its global and versatile

characteristics provide the interoperability of

systems (modality equipments and information

systems) in heterogeneous environments, featuring a

variety of conformity levels.

The PACS concept encompasses several

technologies including hardware and software for

acquisition, distribution, storage and review of

digital images on networked environments. There

are several benefits associated with this technology

are:

 unnecessary physical storage mechanism;

 permanent storage, without quality degradation;

 digital image processing;

 augment of clinical quality information.

PACS offers, to clinical staff, one technological

environment that endows them with the possibility

to remotely access the desired information. This

system makes possible inter-institutional services

such as image based telemedicine.

3 DICOM ARCHITECTURE

ISSUES

PACS-DICOM architecture may now be considered

as a key component in the health care sector. It is

commonly recognized that the data access and

distribution time can be drastically reduced (inter or

intra-institutional), making the image data available

immediately after procedure accomplishment.

In the last decade the sharing of data inside the

institution local-area networks (LAN) (controlled

environments) brings no problems. However, when

we want to promote the remote access to the PACS

from any part of the world, through the Internet,

great barriers appear. In fact, the security measures

implemented by institution network administrators,

which usually grant access exclusively to the HTTP

protocol, blocking all other connections, are limiting

the usage of this architecture on an inter-institutional

basis. Consequently, two major usage scenarios are

compromised:

 Outsource of fully digital image services are

difficult to deploy;

 Cooperative work among the healthcare

professionals cannot be performed.

To cope with this issues, the norm recently added

support the encapsulation of DICOM objects

through HTTP (DICOM-P18, 2004), attempting to

overcome the limitations indicated above.

4 ARCHITECTURE PROPOSAL

A healthcare institution is composed by several

departments like, for instance, radiology and

cardiology ( v.g: Figure 1). In what concerns the IT

infra-structure, each one can have several PACS

servers to store their medical images which can be

accessed by dedicated workstations all connected

through network DICOM protocol (over TCP/IP).

Normally, these servers can communicate

between them and with the institutional public web-

server, which is protected from the outside world by

a firewall that only allows HTTP protocol traffic.

Objecting an unrestricted mobility of image data,

our approach uses the new DICOM 18 part standard,

denominated as WADO (Web Access to DICOM

Persistent Objects), to implement a Web based

platform capable of supporting external access to a

“firewalled” PACS. Moreover, the proposed solution

makes possible to interact with several internal

PACS servers from any outside point.

The developed platform contemplates two

operation modes:

Figure 1: Architecture Implemented.

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 visualization mode: search (by name, study

date, type of study, etc) and listing all the

patients registered in the system;

 reception mode: select a registered (internal)

PACS server and remotely upload some

studies, since the system configuration and

security policies allows that.

In Figure 2 is shown a diagram of the supported

processes by our platform. It is also possible to

observe the workflow for each functionality.

Figure 2: Processes Diagram.

The proposed solution is based on webservices

technology and, consequently, the access to

available DICOM services is done defining (in the

URL) all the fields’ necessary for that purpose. The

DICOM norm (part 18) defines the parameters to

support that service request:

 requestType: the value should be WADO;

 studyUID, seriesUID, objectUID: values that

explicit one object, of a specific series of

studies;

 contentType: mime type(s) desired by the web

client for the response of the server;

 annotation: write patient information on the

retrieved image;

 anonymize: removal of all patient identification

information from within the DICOM object.

http://dicomproject.ieeta.pt/WadoDicom?requestType=W

ADO&studyUID=1.2.250.1.59.40211.12345678.678910&

seriesUID=1.2.250.1.59.40211.789001276.14556172.6778

9&1.2.250.1.59.40211.2678810.87991027.899772.2&cont

entType=application%2Fdicom&anonymize=yes

In the above example an image is requested for a

specific patient using UID's (identifier). The image

format requested is DICOM (defined by the

contentType field), without any patient identification

information.

5 IMPLEMENTED SOLUTION

The solution deployment leads us to create a set of

software modules to support the proposed services.

The visualization of image information in a

given study is also possible. Because presently web

browsers do not have native capacity for processing

and viewing images in DICOM format, it was

necessary to develop a specific viewer. To simplify

the web browser integration, it was chosen to

develop the viewer module in Java, as an Applet that

runs on the client side workstation.

At this moment, the DICOM viewer (Figure 3)

allows basic image manipulation (brightness,

contrast, zoom, etc.), and also the visualization of

dynamic medical image sequences (i.e. films).

In reception mode, the platform allows the

upload of external studies to a selectable internal

PACS storage server. The exams services

outsourced to a private entity can be received in this

way. In every internal PACS server it was necessary

to create a new “organizational instance” to separate

the incoming studies from the other studies produced

inside the department/institution.

The upload service is an extra functionality, not

specified in the DICOM-WADO standard. However,

its implementation has been pertinent, enabling one

scenario of extreme importance to the healthcare

units.

At this moment, we are studying strategies to

implement transmission with data compression. In

fact, there are some medical image modalities with

high requirements of bandwidth to transmit the

information with acceptable temporal costs. Namely,

cardiologic modalities like the XA or the US.

Figure 3: DICOM Image Viewer (Applet).

WEB PLATFORM TO SUPPORT THE SHARE AND REMOTE ACCESS TO MEDICAL IMAGES

293

5.1 Aspects of Software and Network

Engineering

This platform was mainly developed with JAVA

technology. The server’s units were implemented as

Servlets (Hall, 2003) and the clients as Applet

(Prokhorenko).

The WadoClass is the critical module of this

platform, because it contains methods and data

structures necessary to interact with all the servers.

Some servlet-modules were created to work as

interface between the client browser and the

WadoClass (Figure 4). The manipulation of DICOM

objects was handled with the help of PixelMed Java

DICOM Toolkit (Clunie, 2006).

IMA GE S

WADO

Class

WEB SERVER

SERVLET

GET

RET RI EV E

QUERY

RESPONSE

DATA

EXCHANGED

CLI ENT

Figure 4: Interface between client and storage server.

Concerning the communications protocol layer

(Figure 5), all the interactions between the client and

the institution’s portal (i.e. the WebService) are

WADO based, i.e. DICOM objects encapsulated in

HTTP protocol. The communications between the

WebService and PACS servers are implemented

with the conventional DICOM network protocol.

Client

Web Server / Dicom Storage SCP

Through Web Server

HTTP transfer protocol

Through Dicom Storage SCP

Dicom SOP class transfer protocol

Dicom Servers

Temp Directory

Client

Figure 5: Data communications protocol.

Aiming to implement a scalable and easily

reconfigurable solution, a configuration

“WEB.XML” file was used. It allows the storage of

several definitions, necessary for image

communication inside the clinical institution.

6 CONCLUSIONS

Aiming the trans-institutional sharing and remote

access to image patient information, we developed a

platform that encapsulates DICOM objects in the

HTTP protocol, providing a transparent integration

with the traditional departmental of PACS-DICOM

infra-structures. With the actual solution it is

possible to promote, in a secure way, the remote

access to departmental medical images and the

upload of exams produced outside institution.

The paper focus has been on the description of

the overall architecture, since the complexity of

several and important components, namely the

DICOM objects manipulation, cannot be clearly

presented just in the scope of this paper.

The overall result is a cost-effective system with

reduced computational requirements, making

possible its deployment in any existent web server of

any healthcare institution.

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