Denis Tack, MD

The Reseau Hospitalier de Medecine Sociale (RHMS), a not-for-profit organization, comprises five hospitals and four clinics in the Belgian Hainaut province. RHMS relies on 1800 employees, 300 of whom are doctors, to treat 30,000 patients a year. It is the fourth largest medical institution in the Walloon region of Belgium, with a total of 755 beds among its five hospitals. Radiology services are available in each of the sites, which together handle more than 125,000 examinations every year. 

An increasing number of hospitals are accepting the switch from radiographic plates to a filmless PACS environment as a logical transition. The practical benefits of this move were less evident for RHMS, however, because the distributed nature of its medical services required linking information systems over relatively slow long-distance networks, bridging up to 40 km. 

The hospital's IT department chose an in-house information portal, known as SecMed, in addition to linking the geographically dispersed IT systems. The portal provided a single user interface for viewing images from PACS as well as information from other databases containing patient records. Relevant data from all radiology facilities thus became accessible at every desktop in every RHMS site.

The switch from film to filmless required two key steps. RHMS first had to find a PACS solution suitable to the needs of the complex multisite environment. Project managers chose the Telimis Medical PACS, which was capable of integrating with the hospitals' hardware and with preexisting radiology information system, electronic patient record, and hospital information system software. 

RHMS then selected a solution for storage, archiving, and backup to meet predefined criteria for performance, volume of data stored, integration, data protection, and multisite scalability. Budget constraints ruled out the use of an expensive storage area network (SAN) covering the different sites. Instead, managers chose a NAS (network attached storage) application from Telindus. Use of a NAS requires servers that are located between the local area network (LAN) and the SAN. Unlike a SAN, the NAS is connected directly to the LAN and does not require a server to provide archives (images) to users. Access to data is therefore much faster with a NAS. 

The PACS and archiving solutions complemented each other well. 

PACS implementation over five hospital sites required a software and hardware storage infrastructure that is both scalable and reliable. The archiving vendor proposed a combination of decentralized and centralized storage systems, allowing for online replication and nearline backup storage. This solution guarantees ready availability of information and data security. 

For the backup of the NAS for the hospital sites, all images taken during the day are sent to Baudour Hospital at night, using another NAS located in a different building from the Baudour NAS. This is done in case of fire. Because the backup images are on a NAS as well, the crash of the first-line NAS would result in an automatic query to the images of the second NAS, which is identical to the first. This corresponds to a "nearline backup"; for security reasons, a second backup is done on tapes that do not provide direct access. 

Every site has two servers for the local storage administration of the PACS. The main server at each site is coupled with a local hard disk-based NAS-filer (NetApp), which has sufficient capacity to suit image volume at that particular location. The second server is used as a backup to ensure local availability of images if the main server breaks down. About 80% of medical images are consulted locally in everyday practice. The local NAS system provides a first layer of fault tolerance with excellent response times. A local copy of PACS images is also available on the visualization workstations. If all servers and networks go down, physicians can continue working with the most recent images. 

In addition to the local storage infrastructure, all data are replicated every night to the central site at Baudour, which has a centralized NAS system with tape backup. All images produced by the 10 CR systems, six ultrasound scanners, four CT scanners, and one MR unit housed at the five medical facilities are consolidated there. The centralized NAS manages short- and medium-term image archiving as follows: 

*All CR images are compressed with wavelet compression (enabling transfer back to modalities in full DICOM format). The compressed images are stored on the NAS for one month. 

*The same CR images are also compressed with JPEG2000 compression (a compressed DICOM format with higher compression ratio) and stored on the NAS for 30 months. 

*All thick-section CT images (almost always 5 mm) are compressed and archived on the NAS for 30 months. 

*Thin-section CT images are stored on the NAS for one year. This enables 3D comparisons to be made. 

*Long-term image archiving (over 30 years) is based on integration of JPEG images into the preexisting electronic patient record. All ultrasound, MR, CR, and thick-section CT images are included. 

RHMS managers hoped to avoid upgrading existing network bandwidth to save additional expenditure. The PACS vendors used image compression and innovative network management strategies to achieve this goal. Bandwidth remains at 6 Mb/sec between main sites, and 2 Mb/sec between smaller sites. The ability to quickly access full-quality images obtained at any site has contributed greatly to physicians' acceptance of PACS and to the success of the filmless project. 

The RHMS radiology PACS workstations are based on Pentium IV 2.4-GHz processors, each with 2-GB RAM and an 80-GB hard disk (Figure 3). We equipped each workstation with two 1.5-megapixel high-resolution 19-inch screens and one standard 17-inch screen for RIS. The PACS was fully integrated and synchronized with our local RIS software. Each workstation is equipped with dedicated voice recognition software. 

Ten radiographic installations had to be digitized simultaneously, but budgetary constraints prevented the purchase of 10 DR systems. RHMS instead chose to keep its standard radiology equipment and add nine CR systems (Kodak's CR 950 and CR 850), while also replacing film printers with five dry laser printers in 20 x 25-inch film format. 

All film printing for physicians within the RHMS ceased as soon as the CR equipment and PACS workstations were installed. Physicians could instead review images on networked PCs. 

A smart image management solution permits the distribution of images to external referring physicians. Patients' radiological data are automatically burned onto CD-ROMs. Each CD contains images in DICOM and JPEG format, as well as the appropriate viewers. Each of the three main hospitals has three such solutions, including a total of three CD-burner robots. The other, smaller hospitals also use these solutions. 

Film usage declined by 80% six months after the PACS installation. Conventional film is still used for mammography and for CR images if they are requested by patients or referring physicians. RHMS provides only CD-ROMs for CT and MR examinations. 

Prior to PACS, RHMS spent over British Sterling 600,000 per annum on film and British Sterling 150,000 annually on general maintenance. Expenditures fell to well below film expenses after the change, assuming that capital investment in PACS could be written off over five years, and capital investment in CR equipment could be written off over 10 years. Operational cost reductions resulted in net savings from the first year, thanks to the 80% drop in film consumption. 

The PACS enables RHMS imaging services to operate with fewer staff members and allows for flexible workforce planning and improved service levels during holiday periods. Remote diagnoses and assistance from specialized colleagues located at different sites are available when needed. 

Specialists can provide urgent expertise from home through a secure teleworking solution, using a PC and an ADSL-based broadband Internet connection. One radiologist can thus manage evening and weekend cover across all sites. The teleworking application is now fully operational from all sites and causes little perceivable difference in image transfer times. Wavelet and JPEG2000 compression for CR images reduces transfer times for PA and lateral chest radiographs to just a few seconds. A head CT may take just 30 seconds to transmit to a remote location, and an abdominal CT sequence takes two or three minutes. 

The SecMed portal integration also allows individual RHMS hospitals to access and/or exchange records and medical data entered at different sites. Staff can share back-office responsibilities, and administrative tasks due to patient transfer within the RHMS group have been minimized. 

The success of teleworking required several procedural changes. Because radiologists working at any of the five hospitals had to become familiar with the standards of images produced at other RHMS sites, all CR and CT acquisition parameters were unified across the facilities. Close collaboration with the emergency department was also established to obtain a medical survey of patients who were administered intravenous contrast agents for emergency CT scans. Low-dose techniques for CT scanning were instituted. 

The new organizational setup has reduced the number of on-call sessions for radiologists from one every four to five days to one every 13 days, or approximately 2.3 on-call days per month, including just four weekends per year. These reporting duties can be performed from home via the teleworking system, avoiding the need for radiologists to travel long distances to different hospitals. Teleworking solutions are particularly helpful during holidays. 

PACS has also improved the efficiency and quality of image interpretation. Image transfer time between hospitals is at least four times faster than between a hospital and external locations (2 MB/sec). Efficient wavelet compression enables doctors to examine CR images as soon as 50% resolution has been transferred. A chest radiograph received from another RHMS hospital is often interpreted before the transfer of a full DICOM-formatted image is complete. 

Archived images are used for comparisons and are almost always available; this was rarely the case before PACS. CT comparisons are always based on thin-section CT images, permitting 3D reformatting and measurements. All multislice thin-section CT images are archived in DICOM format (compressed) for more than a year. And if a second opinion on a radiological assessment is needed, a colleague with the required expertise is always available, even if that person is located in another building. 

DR. TACK is head of the department of radiology, Reseau Hospitalier de Medecine Sociale in Hainaut, Belgium. PIERRE COLASSE and DIDIER HENNEKENS assisted in the preparation of this article. 

Articles

The Reseau Hospitalier de Medecine Sociale (RHMS), a not-for-profit organization, comprises five hospitals and four clinics in the Belgian Hainaut province. RHMS relies on 1800 employees, 300 of whom are doctors, to treat 30,000 patients a year. It is the fourth largest medical institution in the Walloon region of Belgium, with a total of 755 beds among its five hospitals. Radiology services are available in each of the sites, which together handle more than 125,000 examinations every year.

Multisite organization migrates to filmless

An increasing number of hospitals are accepting the switch from radiographic plates to a filmless PACS environment as a logical transition. The practical benefits of this move were less evident for RHMS, however, because the distributed nature of its medical services required linking information systems over relatively slow long-distance networks, bridging up to 40 km.

The hospital's IT department chose an in-house information portal, known as SecMed, in addition to linking the geographically dispersed IT systems. The portal provided a single user interface for viewing images from PACS as well as information from other databases containing patient records. Relevant data from all radiology facilities thus became accessible at every desktop in every RHMS site (Figure 1).

The switch from film to filmless required two key steps. RHMS first had to find a PACS solution suitable to the needs of the complex multisite environment. Project managers chose the Telimis Medical PACS, which was capable of integrating with the hospitals' hardware and with preexisting radiology information system, electronic patient record, and hospital information system software.

RHMS then selected a solution for storage, archiving, and backup to meet predefined criteria for performance, volume of data stored, integration, data protection, and multisite scalability. Budget constraints ruled out the use of an expensive storage area network (SAN) covering the different sites. Instead, managers chose a NAS (network attached storage) application from Telindus. Use of a NAS requires servers that are located between the local area network (LAN) and the SAN. Unlike a SAN, the NAS is connected directly to the LAN and does not require a server to provide archives (images) to users. Access to data is therefore much faster with a NAS.

The PACS and archiving solutions complemented each other well.

PACS implementation over five hospital sites required a software and hardware storage infrastructure that is both scalable and reliable. The archiving vendor proposed a combination of decentralized and centralized storage systems, allowing for online replication and nearline backup storage. This solution guarantees ready availability of information and data security.

For the backup of the NAS for the hospital sites, all images taken during the day are sent to Baudour Hospital at night, using another NAS located in a different building from the Baudour NAS. This is done in case of fire. Because the backup images are on a NAS as well, the crash of the first-line NAS would result in an automatic query to the images of the second NAS, which is identical to the first. This corresponds to a "nearline backup"; for security reasons, a second backup is done on tapes that do not provide direct access.

Every site has two servers for the local storage administration of the PACS. The main server at each site is coupled with a local hard disk-based NAS-filer (NetApp), which has sufficient capacity to suit image volume at that particular location (Figure 2). The second server is used as a backup to ensure local availability of images if the main server breaks down. About 80% of medical images are consulted locally in everyday practice. The local NAS system provides a first layer of fault tolerance with excellent response times. A local copy of PACS images is also available on the visualization workstations. If all servers and networks go down, physicians can continue working with the most recent images.

In addition to the local storage infrastructure, all data are replicated every night to the central site at Baudour, which has a centralized NAS system with tape backup. All images produced by the 10 CR systems, six ultrasound scanners, four CT scanners, and one MR unit housed at the five medical facilities are consolidated there. The centralized NAS manages short- and medium-term image archiving as follows:

 All CR images are compressed with wavelet compression (enabling transfer back to modalities in full DICOM format). The compressed images are stored on the NAS for one month. 

 The same CR images are also compressed with JPEG2000 compression (a compressed DICOM format with higher compression ratio) and stored on the NAS for 30 months. 

 All thick-section CT images (almost always 5 mm) are compressed and archived on the NAS for 30 months. 

 Thin-section CT images are stored on the NAS for one year. This enables 3D comparisons to be made. 

 Long-term image archiving (over 30 years) is based on integration of JPEG images into the preexisting electronic patient record. All ultrasound, MR, CR, and thick-section CT images are included. 

RHMS managers hoped to avoid upgrading existing network bandwidth to save additional expenditure. The PACS vendors used image compression and innovative network management strategies to achieve this goal. Bandwidth remains at 6 Mb/sec between main sites, and 2 Mb/sec between smaller sites. The ability to quickly access full-quality images obtained at any site has contributed greatly to physicians' acceptance of PACS and to the success of the filmless project.

The RHMS radiology PACS workstations are based on Pentium IV 2.4-GHz processors, each with 2-GB RAM and an 80-GB hard disk (Figure 3). We equipped each workstation with two 1.5-megapixel high-resolution 19-inch screens and one standard 17-inch screen for RIS. The PACS was fully integrated and synchronized with our local RIS software. Each workstation is equipped with dedicated voice recognition software.

Ten radiographic installations had to be digitized simultaneously, but budgetary constraints prevented the purchase of 10 DR systems. RHMS instead chose to keep its standard radiology equipment and add nine CR systems (Kodak's CR 950 and CR 850), while also replacing film printers with five dry laser printers in 20 x 25-inch film format.

All film printing for physicians within the RHMS ceased as soon as the CR equipment and PACS workstations were installed. Physicians could instead review images on networked PCs.

A smart image management solution permits the distribution of images to external referring physicians. Patients' radiological data are automatically burned onto CD-ROMs. Each CD contains images in DICOM and JPEG format, as well as the appropriate viewers. Each of the three main hospitals has three such solutions, including a total of three CD-burner robots. The other, smaller hospitals also use these solutions.

Film usage declined by 80% six months after the PACS installation. Conventional film is still used for mammography and for CR images if they are requested by patients or referring physicians. RHMS provides only CD-ROMs for CT and MR examinations.

Prior to PACS, RHMS spent over British Sterling 600,000 per annum on film and British Sterling 150,000 annually on general maintenance. Expenditures fell to well below film expenses after the change, assuming that capital investment in PACS could be written off over five years, and capital investment in CR equipment could be written off over 10 years. Operational cost reductions resulted in net savings from the first year, thanks to the 80% drop in film consumption.

The PACS enables RHMS imaging services to operate with fewer staff members and allows for flexible workforce planning and improved service levels during holiday periods. Remote diagnoses and assistance from specialized colleagues located at different sites are available when needed.

Specialists can provide urgent expertise from home through a secure teleworking solution, using a PC and an ADSL-based broadband Internet connection. One radiologist can thus manage evening and weekend cover across all sites. The teleworking application is now fully operational from all sites and causes little perceivable difference in image transfer times. Wavelet and JPEG2000 compression for CR images reduces transfer times for PA and lateral chest radiographs to just a few seconds. A head CT may take just 30 seconds to transmit to a remote location, and an abdominal CT sequence takes two or three minutes.

The SecMed portal integration also allows individual RHMS hospitals to access and/or exchange records and medical data entered at different sites. Staff can share back-office responsibilities, and administrative tasks due to patient transfer within the RHMS group have been minimized.

The success of teleworking required several procedural changes. Because radiologists working at any of the five hospitals had to become familiar with the standards of images produced at other RHMS sites, all CR and CT acquisition parameters were unified across the facilities. Close collaboration with the emergency department was also established to obtain a medical survey of patients who were administered intravenous contrast agents for emergency CT scans. Low-dose techniques for CT scanning were instituted.

The new organizational setup has reduced the number of on-call sessions for radiologists from one every four to five days to one every 13 days, or approximately 2.3 on-call days per month, including just four weekends per year. These reporting duties can be performed from home via the teleworking system, avoiding the need for radiologists to travel long distances to different hospitals. Teleworking solutions are particularly helpful during holidays.

PACS has also improved the efficiency and quality of image interpretation. Image transfer time between hospitals is at least four times faster than between a hospital and external locations (2 MB/sec). Efficient wavelet compression enables doctors to examine CR images as soon as 50% resolution has been transferred. A chest radiograph received from another RHMS hospital is often interpreted before the transfer of a full DICOM-formatted image is complete.

Archived images are used for comparisons and are almost always available; this was rarely the case before PACS. CT comparisons are always based on thin-section CT images, permitting 3D reformatting and measurements. All multislice thin-section CT images are archived in DICOM format (compressed) for more than a year. And if a second opinion on a radiological assessment is needed, a colleague with the required expertise is always available, even if that person is located in another building.

DR. TACK is head of the department of radiology, Reseau Hospitalier de Medecine Sociale in Hainaut, Belgium. PIERRE COLASSE and DIDIER HENNEKENS assisted in the preparation of this article.