PACS Archiving & Peripherals

Archive

a place where records or documents are preserved

electronic archive

it serves as the new file room and warehouse for all Dicom imaging modalities

PACS Archive

• It stores all the patient and image data, often on magnetic tape the recior optical disk

• it controls the receipt, storage and distribution of new and historic images

• complex arrangement of computers and storage space, consists of several components, both hardware and software

1. Image manager

2. Image storage

2 Major categories of PACS

Image Manager

• contains the master database of everything that is in the archive

• controls the receipt, and distribution of the images it stores and also controls all the DICOM processes running within the archive

• runs a reliable commercial database such as Syabase

Image Manager

• this database contains only the image header information, not the image data.

• It is also mirrored, meaning there are two identical databases running simultaneously so that if one goes down, the system can call on the mirror and continue to run as normal

Image manager

plays a key role in populating image information into the hospital Electronic Medical Record (EMR)

1. An order is placed in the RIS for a radiology study

2. The images are acquired and sent to the archive

3. The image manager strips the image header from each image and assigns a pointer to each image or series of images

4. The database files the information in various fields & communicates back to the RIS to verify certain information

5. The study is then queried, and the pointers locate the images on the

archive server and send the images to the workstation

Process for Image manager

Image Storage

• Consists of the physical storage device of the archive system

• Consists of two or three tiers of storage: A tier is a level, layer, or division of something

• In an archive server, a tier represents a specific level of archive: short-term, mid-term, or long-term

SHORT-TERM Image Storage

Being online or available very quickly, 3-5 seconds

LONG-TERM Image Storage

Means near line, images that must be retrieved from a tape or disk storage device, 1-5 minutes & brought to a Redundant Array Of Independent (Inexpensive) Disks (RAID

SHORT-TERM Storage

• commonly a RAID

RAID-(Redundant Array of Independent Disks

composed of several magnetic disks or hard drives that are linked together in an array. Size ranges from Several Hundred Gigabytes to Several Terabytes

(500 GB – 3T)

David Patterson, Garth Gibson & Randy Katz

They coined the term RAID in an article entitled “A Case for Redundant Arrays of Inexpensive Disks (RAID)”

1. Magneto-optical Disk

2. Digital Versatile Disk

3. Ultra Density Optical

4. Tape

5. Magnetic Disk

types of Optical Disk

MAGNETO-OPTICAL DISK

▪ Very similar to a compact disk (CD) or digital versatile disk (DVD)

▪ Read optically with a laser, but the disk itself is housed within a plastic cartridge

▪ More reliable than some of the other long-term storage options

▪ Disks are robust and can withstand many years of reading

DIGITAL VERSATILE DISK

▪ 1st introduced for use in video

▪ Have much higher capacity than CD

▪ Holds up to 17 GB compared to CD 650 MB

▪ Least expensive method for long-term archiving per gigabyte

ULTRA DENSITY OPTICAL

▪ New generation MOD

▪ Uses blue laser technology in its Read & Write activities

▪ Cost less than MODs

TAPE

▪ Tape libraries provide the greatest scalability of the longterm archive options

▪ Hundreds of terabytes to even a petabyte

▪ Fairly low-cost archive medium that comes in various sizes

MAGNETIC DISK

These tapes are contained within a jukebox or library that has multiple drives & a robot arm to move the tapes in & out of the drives

Disadvantage:

Unreliability over multiple uses

1. Linear Tape Open (LTO)Open-format technology- multiple sources

2. Digital Linear Tape (DLT)

3. Advanced Intelligent Tape (AIT)

3 Types of Magnetic Tape