ARCHIVES
Does the Catella Archive perform DICOM Query/Retrieve?
First of all, we were one of the first companies to implement Level 5 RAID architecture. Tapes are slow and can break. CD's or DVD's can multiply quickly and become unruly to manage. RAID, (Redundant Array of Independent Drives) uses highly reliable, rapid access hard drives. Using RAID architecture allows images to be stored on-line using a technology that allows rapid access to your data. By comparison, access to images using tapes or CD's takes minutes. RAID access takes seconds. The transfer of data from a RAID archive to your workstation is only dependent upon the speed of your network. Also the cost of hard drives is constantly dropping and the capacity of these units is increasing at an equal or greater rate. Therefore, when you need additional storage, upgrading is easy and increasingly cost effective.
The Catella RAID archive has the added advantage of including an automatic backup system. All Catella RAID archives come with a system that makes a copy of your archives on a removable hard drive. When this hard drive is filled, it can be replaced and the backup copies can be stored offsite for safekeeping. In fact, the Catella archive architecture makes a back up copy even before it is logged on to the archive. This backup system also acts as a Gateway that routes the images to workstations and other destinations that you select. Because we understand that this is the critical component in our imaging network, all Catella archives come with a redundant Gateway backup system.
Does the Catella Archive perform DICOM Query/Retrieve?
Yes. The AMS Cat-Arch product not only supports DICOM Query/Retrieve (which allows a doctor to "pull" images from it), but it also has the capability to allow a tech to "push" images from it to a particular destination. This allows a scheduling nurse to preload a doctor's Catella workstation so that the doctor doesn't need to spend time retrieving patient studies.
How much memory do I need to purchase for my archive?
While the number of images produced by modern x-ray equipment is increasing (example: multi-slice CT), the price of storage continues to drop. We recommend that you purchase archive capacity for approximately two years' storage needs. There is no reason to buy storage too far in advance. Call AMS to help you determine your need.
AMS' archives are quoted in size based on the number of sheets of film that they can hold. This makes it easier to estimate what is needed. Determine how many sheets of film your institution uses in a year and multiply that by 2. That is the approximate size archive you want to start with. You will need to increase it in two years (to allow for storage of new images – the first two years' images are stored and will remain on the archive), but costs should be much less then. To roughly size an archive in bytes, you will need about 1/2 terabyte for every 10,000 studies .
Is a UPS necessary on an archive?
Most power outages last less than one second. A UPS that can handle one or two minutes will solve over 95% of the electrical problems that most sites experience. However, longer outages certainly can occur. If you feel that it is appropriate to protect against those, large UPS systems can be obtained. We can provide you with requirements depending on the perceived need.
We have done testing on the archive that includes turning it off in mid-transfer (inbound). While the file being received is damaged, the Archive knows that it has not finished the image and reprocesses it. We have not seen any image loss on the archive. And, remember, Catella archives also include a removable copy. We understand that you can never have too much protection, but it needs to provide value (be worth the extra cost). What about the Web Server and the Image Router? Should they be protected also? UPS systems that can support an archive for 10 to 15 minutes cost less than $200. Larger UPS systems can also be specified, but they are significantly more expensive. To specify a UPS, we basically need to know how long a power outage you want to be able to ride through.
What happens to image files that are in the process of being accepted by the Archive should the Archive shut down before the image save is complete?
In the Catella system, images first go to the Catella Gateway before being sent to the archive, workstations, and other destinations. If the Archive does not complete its save function, the Gateway will not receive a “received” message back from the Archive. The Gateway will attempt to re-send the image to the Archive until it has been saved.
What are the “benchmarks” that determine the color of the Gateway Screen and can these be changed?
The background color of the Image Gateway screen is a visual reminder of how much unused storage remains on the image backup removable hard drive. Green means there is plenty of remaining storage. Yellow is a warning that storage levels are dropping…be prepared to change the removable hard drive. Red means a change is required.
These changes are determined based on the amount of storage remaining on the hard drive. Factory settings change the screen from green to yellow when there is 10 gig of free storage capacity. The screen changes from yellow to red when there is less than 2 gig of free storage capacity left.
These amounts can be changed. Contact AMS with your request.
How are we going to handle distribution of images when a new reading doctor is added?
There are currently three practical ways to manage multiple diagnostic Catella workstations on a system. All of them require a device called the Image Gateway. Instead of images going directly to a single Catella workstation, all images are routed to the Image Gateway, which is typically located at the main reading site. The Image Gateway's job is to distribute images to the proper places, including workstations, archives and Web servers.
The three distribution models are:
1). Send all images to all diagnostic workstations. Doctors are responsible for determining who is assigned to each patient. This is a manual communications process (e.g. by telephone or paper orders or files).
2). Rules are established that allow a patient's images to be sent only to the workstation of the doctor who is responsible for reading that patient. For example, the Image Gateway could send all images that arrive between the hours of 8am and 5pm to workstation 1. All off-hours images could go to workstation 2. At any time, either workstation could Query and Retrieve images not originally sent to it. A different rule could be that every MRI goes to workstation 1 and all other images go to workstation 2.
3). All images are sent to all workstations. An automatic locking scheme is implemented so that workstations will skip any image that is being looked at on another workstation. When a patient is diagnosed on one workstation a message is sent that marks the image as diagnosed on all other workstations.
Method 3 is preferable. Being automatic, it takes the least amount of doctor intervention. Method 2 can be advantageous in situations where limited bandwidth in communications lines makes it desirable not to send images to workstations where there is a high likelihood that they will not be needed.
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