PACS.ppt

PACSPACS

What is PACS ?What is PACS ? PPicture icture AArchiving and rchiving and CCommunications ommunications

SSystem (actually more than name implies)ystem (actually more than name implies) PACS provides the ability to electronically PACS provides the ability to electronically

(ie, computer and network technology) to:(ie, computer and network technology) to:– Input images from (digital) modalitiesInput images from (digital) modalities– Distribute images to PCs and workstationsDistribute images to PCs and workstations– Read on computer display (diagnostic & clinical)Read on computer display (diagnostic & clinical)– Store (both long and short term) imagesStore (both long and short term) images– Transmit (to other areas or off-site)Transmit (to other areas or off-site)

Reasons for PACSReasons for PACS More Efficient Workflow:More Efficient Workflow:

– RTs spend up to 50% of time “handling” filmRTs spend up to 50% of time “handling” film– Reader cannot effectively interpret exams on Reader cannot effectively interpret exams on

film consisting of hundreds of images (eg, film consisting of hundreds of images (eg, MSCT) MSCT)

Faster Medical Care DeliveryFaster Medical Care Delivery::– Images available to reader at exam completionImages available to reader at exam completion– Clinical consults possible via remote accessClinical consults possible via remote access

Potential Cost Savings:Potential Cost Savings:– Eliminate lost filmEliminate lost film– Improved productivity Improved productivity – Eliminate lost film preventing lost revenueEliminate lost film preventing lost revenue

PACS COMPONENTSPACS COMPONENTS Network Network (to acquire/distribute/transmit)(to acquire/distribute/transmit) Servers Servers (to maintain/control database)(to maintain/control database) Storage Storage (secondary storage devices)(secondary storage devices)

– Short term (current studies)Short term (current studies)– Long term (archives)Long term (archives)

Workstations Workstations (reading and clinical (reading and clinical review)review)

In many cases, specials requirements In many cases, specials requirements for PACS push the limits of technologyfor PACS push the limits of technology

PACS Basics: “Size” of StudiesPACS Basics: “Size” of Studies

Useful Facts and Terms to Know:Useful Facts and Terms to Know: 1 K x 1 K = 1 M (eg, 2K x 1.5 K = 3 M) 1 K x 1 K = 1 M (eg, 2K x 1.5 K = 3 M) 1 K x 1 M = 1 G (Gig), etc1 K x 1 M = 1 G (Gig), etc Digital images consist of a “matrix” of Digital images consist of a “matrix” of

“pixels”“pixels” Each pixel contains a binary number Each pixel contains a binary number

representing the gray level of the pixelrepresenting the gray level of the pixel One or two bytes/pixelOne or two bytes/pixel

– One: (US, NM)One: (US, NM)– Two (CT, MR, DR)Two (CT, MR, DR)

PACS Basics: “Size” of StudiesPACS Basics: “Size” of Studies Example 1: 4-View Digital Radiography Example 1: 4-View Digital Radiography

Exam:Exam:– 2K x 2.5K matrix: 2K x 2.5K = 5 MegaPixels (MP)2K x 2.5K matrix: 2K x 2.5K = 5 MegaPixels (MP)– 5 MP x 2 bytes/pixel = 10 Megabytes (MB)/Image5 MP x 2 bytes/pixel = 10 Megabytes (MB)/Image– 4 images/exam x 10 MB/image = 40 MB/Exam4 images/exam x 10 MB/image = 40 MB/Exam

Example 2: Average CT Exam (300 images):Example 2: Average CT Exam (300 images):– 512 x 512 matrix: 0.5K x 0.5K = 0.25 MegaPixels512 x 512 matrix: 0.5K x 0.5K = 0.25 MegaPixels– 0.25 MP x 2 bytes/pixel = 0.5 Megabytes/image0.25 MP x 2 bytes/pixel = 0.5 Megabytes/image– 300 images/exam x 0.5 MB/image = 150 MB/exam300 images/exam x 0.5 MB/image = 150 MB/exam

Example 3: Large CT Exam (1200 images):Example 3: Large CT Exam (1200 images):– 0.5 Megabytes/image (same as above)0.5 Megabytes/image (same as above)– 1200 images/exam x 0.5 MB/image = 600 MB/exam1200 images/exam x 0.5 MB/image = 600 MB/exam

PACS Components: NetworkPACS Components: Network ““Communications” part of PACommunications” part of PACCS:S:

– Acquire/ distribute/transmit imagesAcquire/ distribute/transmit images– Entirely “standards” basedEntirely “standards” based

Network Hardware:Network Hardware:– Ethernet (most common) using 10- or 100-Base TEthernet (most common) using 10- or 100-Base T– Gigabit (1000Base-T) & Fiber channel Gigabit (1000Base-T) & Fiber channel

“backbones”“backbones” Protocols and Software:Protocols and Software:

– Network protocol: Network protocol: TCP/IPTCP/IP (the Internet Standard) (the Internet Standard)– Image Formats: Image Formats: DICOM 3 (this is key)DICOM 3 (this is key)

PACS Components: Network IssuesPACS Components: Network Issues Average CT Exam (150 MB) on 100-Base TAverage CT Exam (150 MB) on 100-Base T

– 100 Base-T: maximum 100 Mbits/sec (60 average)100 Base-T: maximum 100 Mbits/sec (60 average)– 150 Mbytes x 8 bits/byte = 1200 Mbits150 Mbytes x 8 bits/byte = 1200 Mbits– 1200 Mbits/60 Mbits/second = 20 seconds 1200 Mbits/60 Mbits/second = 20 seconds

Large CT Exam (600 MB) on 100-Base TLarge CT Exam (600 MB) on 100-Base T– 100 Base-T: maximum 100 Mbits/sec (60 average)100 Base-T: maximum 100 Mbits/sec (60 average)– 600 Mbytes x 8 bits/byte = 4800 Mbits600 Mbytes x 8 bits/byte = 4800 Mbits– 4800 Mbits/60 Mbits/second = 80 seconds 4800 Mbits/60 Mbits/second = 80 seconds

(seems like forever if you’re sitting and waiting)(seems like forever if you’re sitting and waiting)

PACS COMPONENTSPACS COMPONENTS

– Must maintains database for 5 or more yearsMust maintains database for 5 or more years– Size and speed requirements depend on facilitySize and speed requirements depend on facility– May have multiple servers to share dutiesMay have multiple servers to share duties– May have “mirrored” servers for high availabilityMay have “mirrored” servers for high availability

Network Network (to acquire/distribute/transmit)(to acquire/distribute/transmit) Servers: maintain/control databaseServers: maintain/control database (database (database is the exam directory: is the exam directory: patient demographics, patient demographics, what exams what exams performed and when, where the performed and when, where the images images are stored, etc):are stored, etc):

PACS COMPONENTSPACS COMPONENTS Network Network (to (to

acquire/distribute/transmit)acquire/distribute/transmit) Servers Servers (to maintain/control database)(to maintain/control database) Storage Storage (using secondary storage (using secondary storage

devices)devices)– Short term (current studies):Short term (current studies):– Long term (archives)Long term (archives)

PACS Components: StoragePACS Components: Storage

– For current studies (and relevant prior studies)For current studies (and relevant prior studies)– Need fast retrieval: when reader selects exam to Need fast retrieval: when reader selects exam to

read, server must deliver it within secondsread, server must deliver it within seconds– Most Common: RAIDMost Common: RAID– Typically need 3-4 weeks of short term storageTypically need 3-4 weeks of short term storage– Prefer to have ~ 1 year (rapid access to priors)Prefer to have ~ 1 year (rapid access to priors)– Actual amount is cost/performance trade-offActual amount is cost/performance trade-off

Short Term Short Term Storage: Storage:

PACS Components: StoragePACS Components: Storage

– Speed not as critical (usually exams pre-fetched)Speed not as critical (usually exams pre-fetched)– Must have copies at two sites (JCAHO, HIPAA)Must have copies at two sites (JCAHO, HIPAA)– Need to archive at least 5 years (CT state law)Need to archive at least 5 years (CT state law)– Type of archive basically cost/speed tradeoffType of archive basically cost/speed tradeoff

Archive Technologies:Archive Technologies:– Hard disk based: fastest, most expensiveHard disk based: fastest, most expensive– DVD: intermediate speed, moderate costDVD: intermediate speed, moderate cost– Tape (DLT, LTO, etc): cheap but slow (reliable??)Tape (DLT, LTO, etc): cheap but slow (reliable??)– Offsite archiving (Service Provider)Offsite archiving (Service Provider)

Long Term Storage: Long Term Storage: For For “archived”studies“archived”studies

PACS Storage Issues: Data VolumePACS Storage Issues: Data Volume

– CT:CT: 40,000 exams x 150 MB/exam = 6 Terabytes 40,000 exams x 150 MB/exam = 6 Terabytes – Radiography:Radiography: 75,000 x 40 MB/exam = 3 Terabytes 75,000 x 40 MB/exam = 3 Terabytes– All others:All others: 1 Terabyte 1 Terabyte TOTAL: 10 TB/yearsTOTAL: 10 TB/years

Archive Requirements:Archive Requirements:– 5 years x 10 TB/year = 50 Terabytes5 years x 10 TB/year = 50 Terabytes

Note:Note: 50 TB = 51,200 Gigabytes !! 50 TB = 51,200 Gigabytes !! 50 TB = 52,428,800 Megabytes !!50 TB = 52,428,800 Megabytes !!

Volume of Radiology Data (HH):Volume of Radiology Data (HH):

PACS COMPONENTSPACS COMPONENTS Network Network Servers Servers StorageStorage WorkstationsWorkstations

–reading/clin viewreading/clin view–usually high end usually high end PCPC

–Diag: 2-4 Diag: 2-4 monitors monitors

–Often 3rd monitor Often 3rd monitor (for color/text) (for color/text)

PACS Components: WorkstationsPACS Components: Workstations

Diagnostic Quality Displays (expensive)Diagnostic Quality Displays (expensive)– Very High Resolution: Very High Resolution:

• 2K x 1.5K for radiography (1280x1024 max-2K x 1.5K for radiography (1280x1024 max-avg PC)avg PC)

• 2K x 2.5K common (required for digital 2K x 2.5K common (required for digital mammo)mammo)

– Very High Brightness: to display graylevelsVery High Brightness: to display graylevels• 10 bits/pixel (1024 graylevels displayed 10 bits/pixel (1024 graylevels displayed • 700 cd/m2 (70-120 for normal CT monitor)700 cd/m2 (70-120 for normal CT monitor)

Diagnostic Workstation: (for Diagnostic Workstation: (for radiologists)radiologists)