Assistant Professor of Radiology
Department of Clinical Radiology
University Hospital of Mannheim,
The University Hospital of Mannheim is a medical faculty affiliated to the University of Heidelberg in southwest Germany. The hospital has 18 clinical departments (including surgery, internal medicine, ophthalmology and gynaecology) and 12 departments for diagnostics and research. Approximately 4,500 employees care for nearly 300,000 in- and outpatients each year.
The Department of Clinical Radiology oversees most of the hospital’s radiological practice, from conventional radiology, computed tomography (CT), magnetic resonance imaging (MRI), pediatric radiology and interventional radiology to nuclear medicine and neuroradiology. Radiology staff rely on approximately 150 radiology information system (RIS) workstations to access patient data to plan and report examinations. Eighty image visualisation and postprocessing workstations handle the 40 TB of image data stored by a central picture archiving and communication system (PACS). In addition, four PACS department servers, each from a different solution vendor, support data buffering and image distribution.
Managing growth in imaging data
Imaging data is seeing rapid growth in both volume and complexity. New scanning and measurement devices capture up to 1,000 times more data than in previous generations. While more – and better – imaging data brings obvious benefits, it also has triggered the need for powerful viewing and postprocessing workstations that allow fast and multidimensional access to high-resolution volumetric data sets.
However, processing large data volumes is not the only challenge for today’s workstations. For an imaging workstation to achieve optimal productivity, it must, for example, be able to fuse data gathered from different modalities and/or apply special analytic algorithms that allow radiologists to visualise only the relevant diagnostic information. Because few doctors are experts in image processing, networking and 2D/3D algorithms, all these features should be accessible via an intuitive user interface.
Leading vendors of medical imaging tools offer workstation solutions that target those needs. Yet most 2D/3D Digital Imaging and Communications in Medicine (DICOM) workstations cost as much as $40,000–$60,000, with the bulk of costs driven by software licences. As a result, budget-strapped hospitals and clinics may be forced to care for patients without the advantage of advanced radiological imaging tools.
And this triggers another, more serious, cost: without proper resources, radiology teams may face a disrupted workflow that could keep them from quickly and efficiently delivering lifesaving diagnoses and treatment.
Open-source ideology is well established in the software industry but is still relatively new in healthcare. With the constant introduction of new regulatory requirements, IT costs, software licensing fees and other liabilities now push healthcare managers to look to open-source technology to resolve the challenges of health IT integration and digitalisation.
IT industry analyst and consultant Michael Goulde says: “Open source is increasingly likely to become the dominant model for creating software to improve the quality of care in a cost-effective way because companies such as RedHat, MySQL and JBoss have demonstrated that the model is viable; because computer companies such as IBM, HP and Sun Microsystems support the model; and because several healthcare-oriented open-source projects have proved it works.”(1)
With open source, development accompanies adoption. Its greatest benefit is the community support it offers. Development is realised by anyone who expresses a need for the application, thereby favouring a community “pull” rather than a commercial “push”. And the contribution and testing by many often results in better and more reliable products, with a fast update rate. The key drawback is that adopting open source also means taking on more responsibility for one’s own support and often hiring third-party intervention. Many vendors, however, are moving to a support-centred business model for open source.
The benefits of OsiriX
With OsiriX (www.osirix-viewer.com), an open-source imaging workstation application available only for Mac computers running OS X, doctors have access to most of the common features of radiological imaging provided by proprietary solution vendors. OsiriX supports virtually all modality types and features DICOM networking functions, sophisticated image organisation tools and 2D, 3D and 4D reconstruction tools.
The application features multiplanar, surface-shaded and volume-rendering algorithms and includes many of the same advanced functions as commercial DICOM workstations such as 4D imaging (required for cardiac MRI or CT) and sophisticated image-fusion methods. OsiriX is also highly customisable via third-party plug-ins and can be integrated into a wide range of workflows and PACS.
OsiriX benefits from its genesis in the open-source community. This has allowed it to mature rapidly into one of the most complete and feature-rich radiological software solutions currently available. Numerous open-source developers regularly incorporate new features at the request of end-users. Although free radiology-oriented software projects exist for other operating systems, including Linux and Microsoft Windows, none can equal the features and performance of OsiriX. Similarly, it is difficult for any single medical imaging vendor to match the blistering pace of innovation that this project enjoys.
Meeting FDA and CE regulations
In most countries, software used for medical image reading has to fulfill certain legal requirements. These include developing the software in a well-defined and managed process and under quality and risk management controls. Requirements also cover aspects such as software documentation (eg, DICOM conformance statements, technical and user documentation) and an incident management system. Using a system developed according to these standards results in reliable, reproducible and consistent outputs under stable conditions.
The fluid nature of open-source software development, however, makes the process difficult. Ongoing community development means that open-source code can change constantly, and this may render the application unstable – and would also make any QA result invalid.
Fortunately, third-party institutions can select a defined development state for an application and use that version for bug fixes, enhancements and modifications.
Once the software clears the processes required for use under US Food and Drug Administration (FDA) and European Conformité Européenne (CE) regulations, the application can be offered as a complete solution that includes software, manual, service and support. This enables hospitals to acquire OsiriX versions that have been processed according to either US or European regulations.
The Open Source OsiriX version may be used for some professional clinical work, but this is not recommended, as any malpractice issues caused by software errors must then be resolved by the user.
Aycan workstation OsiriXPRO is a modified version of OsiriX (www.aycanus.com, www.aycan.de). The software has earned 510(k) clearance for use as a medical device according to the US FDA (510(k) Number: K063470), and it has a CE certificate for use throughout the European Union and Turkey.
Available commercially, Aycan workstation OsiriXPRO incorporates bug fixes and validated and exclusive plug-ins. Furthermore, the software comes with a comprehensive user manual, a computer-based training CD and various training and service options.
dcm4chee (www.dcm4che.org) is an open-source, flexible and scalable PACS server software that integrated smoothly with infrastructure and with all our modalities and workstations. It is a cross-platform system developed in Java and distributed as embedded components in a Java Enterprise Edition (JEE) application server. Acting as a PACS archive, dcm4chee is able to store, query and retrieve any type of DICOM object. In addition, support is included for MPPS (modality performed procedure step), GPWL (general-purpose worklist management), MWL (modality worklist), storage commitment, instance availability notification, study content notification, output content to CD media, and more. The archive includes an integrated Health Level 7 (HL7) server, which can act on ADT (admission, discharge and transfer), ORM (object-relational mapping) and ORU (order result) message types. WADO (DICOM Part 18: Web Access to DICOM Objects) and RID (IHE retrieve information for display) interfaces enable access to the archived content from the web.
The components work together to provide a reference implementation of many IHE actors and integration profiles.
Apple Mac Pro and Mac OS X
Apple Mac OS X is commonly regarded as the most advanced operating system available, combining the powerful and security-aware techniques of UNIX systems with a user-friendly interface. Via modern programming techniques such as Objective-C and the Cocoa framework, Mac OS X can support new generations of highly stable and scalable tools for use in professional environments. And with Apple Mac Pro systems, the requirements of a high-performance radiological workstation can be easily met, with a single workstation powered by four or eight Intel Xeon processor cores, up to 16 GB of memory, as much as 3 TB of disk storage and three graphics card options, one of which offers stereo viewing capability.
Our dmc4chee PACS has been installed on a Mac OS X Server, which provides top-performance components. Apple Server tools ease remote monitoring and administration and also offer many more possibilities for future usage (eg, iCal Server, file and print services).
Integrating Mac in the hospital IT infrastructure
Directory services help organise users and control their access to computers, peripherals and network resources in a multiclient IT setting. They allow IT managers to implement uniform-access policies across the organisation by structuring users and computers in units and groups. This allows users to log on to any computer system to access their specific working environment. For directory services, however, heterogeneous IT environments can prove troublesome.
Due to the popularity of Microsoft Active Directories, many Mac OS X or UNIX/Linux clients are not supported by IT departments, and some medical facilities even forbid the introduction of alternative operating systems.
The first step is to enable the OsiriX workstation to access directory services so that users can provide transparent authentication at file and print servers and make use of the hospital’s email and address book architectures on a single sign-on basis. Current Mac OS X versions provide powerful tools for integrating a Mac client system into an Active Directory and for providing transparent authentication of users at associated services such as LDAP or Microsoft Exchange Server. Administrators can use the Mac OS X Directory Access application to specify integration details and to sign up the Mac system to the Microsoft Active Directory.
“Managed” Microsoft Active Directory users logging in to the Mac OS X environment access a temporary local home directory structure similar to the standard Microsoft Windows desktop. This includes the personal files normally found on Windows clients and synchronises with the user’s Active Directory profile on logging out. Users also can transparently access network resources such as file servers and printers via the Mac OS X dialogues without use of redundant authentications.
We also configured Apple Mail and Address Book applications to access Microsoft Exchange accounts and associated LDAP services, which means no futher action need be taken to integrate the Mac with the hospital’s email and address book architecture.
Access to hospital and radiology information systems
Today, radiology departments rely on a radiology information system (RIS) to manage patient and examination information, scheduling and accounting. Although an increasing number of RIS implementations are available for the Apple Mac OS X platform, most RIS clients are accessible only on Microsoft Windows.
Our radiology team members access the GE Medora RIS version 3.9.12 in two ways: first, via a dedicated database front end for examination planning and documentation; and secondly, through a set of Microsoft Word plug-ins for report generation and online speech recognition using Philips SpeechMagic 5.1 SR1. Both are Windows-only applications.
Because the RIS is not integrated with the Active Directory, users must log on to the database separately — IT administration views this as an additional security enhancement. For our hospital information system (HIS), we use SAP R3 Release 4.7.2, which provides general patient information and interfaces to our ordering and accounting processes. The HIS, RIS and PACS systems interconnect via HL7 protocols, allowing capabilities such as automatic patient data transfer. This means that radiology workstations can still access relevant HIS information without the HIS client application being installed on a radiology viewing and reporting system.
Creating a virtual PC
To access the RIS from the Mac platform running OsiriX, we leveraged virtualisation software that emulates standard PC hardware so users can run Windows and Windows-compliant applications on Macs. The “guest operating system” behaves as it would on a PC, and the advanced central processing units driving today’s Mac Pro systems derive very acceptable performance from this “virtual machine”.
Several Windows virtualisation options are available for Apple Mac OS X. We chose Parallels Desktop for Mac to run a virtual Microsoft Windows XP system and provide OsiriX workstation users with access to the department’s standard RIS clients. We configured the virtual machine to start up automatically at the user’s login. Optionally, under a so-called “coherence” mode, virtualised applications running on Windows can seamlessly integrate into the Mac OS X desktop. Built-in network address translation eliminates the need to assign a separate IP (internet protocol) address to the virtual machine.
Access to PACS
OsiriX enables seamless integration into a PACS architecture because the application’s built-in networking technologies are DICOM-compliant. At our facility, OsiriX handles DICOM images from 15 different modalities, and it networks with several PACS components without any reported problems. When it is integrated with OsiriX, other workstations can query OsiriX and pull images from its database. It also supports simultaneous queries from multiple systems, and this enables much more efficient image distribution by department servers. In addition, the OsiriX image database can be shared (using password protection) with other OsiriX stations over the Apple Bonjour powerful “zero-configuration” communication protocol. Bonjour networking to share images is notably faster than DICOM transfers.
Ensuring display quality
Computer performance, memory capacity and interoperability are all important aspects of a modern radiological workstation. But none of these is of much significance if radiologists view imaging data on a monitor with unreliable or substandard display quality. Indeed, the value of even the most detailed 2D and 3D images is dramatically diminished when displays do not meet accepted quality standards.
Legislation and medical society standards all over the world specify the requirements that all displays must fulfill if they are used for primary radiological reporting. Depending on the type of images displayed, these generally include limits for brightness, contrast, resolution and homogeneity. Different standards can apply to the various imaging modalities and differing use of images.
Conformity and constancy tests
To confirm that displays meet minimum image-quality standards, administrators must perform special tests. On setup, an initial conformity test ensures that the display is applicable to a given environment. Regularly performing constancy tests documents the changing visual quality of the system. The display’s lighting settings influence the frequency of these tests. While many monitors allow automatic adjustment of brightness and contrast, many others – including Apple Cinema Displays – do not. These require constancy tests every three months. And every day, workstation users must conduct a visual check of the grayscale presentation and geometrical accuracy by examining the SEMPTE (Society of Motion Picture and Television Engineers) test pattern. To conduct conformity tests for the 30-inch Apple Cinema Displays, we used a subset of the given test criteria, according to the intended use.
Apple Cinema Displays meet image-quality requirements for radiology reporting in all application categories, including grayscale presentation standards, constancy tests for brightness/contrast and they have passed conformity tests. However, in homogeneity tests, variations in luminance in the panel corners call for more frequent constancy testing in the future. The antireflection coating also causes slight blurring on brighter parts of chest X-rays, but many radiologists found that it had no negative impact. However, we recommend that future Apple Cinema Display models should be re-evaluated for homogeneity and coating. These few shortcomings may lead some hospitals to reserve the use of this system for Category B applications. Display-independent calibration software allows users to implement other display types for Category A applications. (Category A covers digital radiographic images such as chest X-rays; Category B covers all other types of images, such as CT or angiographic data.)
Mac-based workstation security
Mac-based workstations can be comprehensively secured, and they support the management of Active Directory users. We installed a Sophos Anti-Virus client and integrated it with the hospital’s signature and engine updating service. Mac OS X firmware password protection, device access control, application blocking and other detailed settings enable per-user or general-access controls. To apply these controls to Active Directory users, administrators must either expand the Active Directory scheme to support Mac-specific rule sets or set up an Open Directory on a separate Mac OS X server system and then configure both Active Directory and Open Directory services.
After 10 weeks of routine work on the Mac-based OsiriX workstation, six radiologists provided feedback on the workflow solution and image quality. Speed and stability were rated Very Good, especially compared with several other (old and new) workstations used in the department. Learning curve difficulty was rated Average, although most colleagues were not specialists in 2D/3D image processing and were new to Mac systems. RIS and PACS integration was rated Good, and all the services needed for daily work could be accessed easily. Users noted that online speech recognition on the Mac-based virtual machine worked as it does on a “real” Windows PC. The dcm4chee on Xserve performance was very satisfactory. The only drawback is that installation/upgrades require manual work on the console. This calls for a basic server knowledge or third-party intervention. There has been no failure in accessibility, speed or reliability since installation and the whole system manages seamlessly the terabytes of data pushed from the different modalities. Overall, users said they were satisfied with the workstation. Only the slightly inhomogeneous display and relatively coarse antireflection coating were cited as major disadvantages for chest X-rays.
The OsiriX/Mac imaging workstation is a reliable, stable and affordable system for daily work in a radiology department. The combined solution meets the imaging and display standards set out by international and German regulatory bodies and was easily integrated into a Windows-based IT infrastructure.
- Goulde M, Brown E, Rymer J, Hartzband D. Open source software: a primer for health care leaders. IHealth Reports, Forrester Research, Mar 2006. p. 5.
For the original white paper visit http://images.apple.com/science/pdf/Radiology_White_Paper20070814.pdf