impact of various imaging modalities on pacs archiving and storage eugene mah, m.sc. jay crawford,...
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Impact of various Impact of various imaging modalities on imaging modalities on PACS archiving and PACS archiving and storagestorage
Eugene Mah, M.Sc.Eugene Mah, M.Sc.
Jay Crawford, MHAJay Crawford, MHA
Medical University of South Medical University of South CarolinaCarolina
PACS Archive AnalysisPACS Archive Analysis
11 years worth of archived studies 11 years worth of archived studies were analyzedwere analyzed
Monthly data obtained for 7 Monthly data obtained for 7 modalitiesmodalities
Storage requirements computed Storage requirements computed based on estimated image file sizesbased on estimated image file sizes
Did not consider compression by Did not consider compression by the archivethe archive
Modalities ExaminedModalities Examined
CTCT Computed TomographyComputed Tomography
MRMR Magnetic Resonance ImagingMagnetic Resonance Imaging
CRCR Computed RadiographyComputed Radiography
NMNM Nuclear MedicineNuclear Medicine
MGMG Digital MammographyDigital Mammography
PTPT PET/PET CTPET/PET CT
USUS UltrasoundUltrasound
Image File SizesImage File Sizes
ModalityModality Matrix SizeMatrix Size File Size File Size (MB)(MB)
CTCT 51251222 0.50.5
MRMR 51251222 0.50.5
CRCR 2048x24942048x2494 1010
NMNM 25625622 0.1280.128
MGMG 4096x33284096x3328 26.626.6
PTPT 12812822 0.0320.032
USUS 640x480640x480 0.30.3File sizes based on 2 bytes/pixel except for US which are screen captures (1 byte/pixel)
PACS Archive AnalysisPACS Archive Analysis
Looked for changes in storage Looked for changes in storage requirements due torequirements due to– additional modalitiesadditional modalities– additional equipmentadditional equipment– changes in technologychanges in technology– protocol changesprotocol changes– increased volumeincreased volume
Data collected from DB Data collected from DB queryquery Number of studies per monthNumber of studies per month Total images per monthTotal images per month Average images/study per monthAverage images/study per month Maximum images in a studyMaximum images in a study Minimum images in a studyMinimum images in a study
Computed statisticsComputed statistics
GB per monthGB per month For CT and MR:For CT and MR:
– Number of studies per month per Number of studies per month per scannerscanner
– Number of images per month per Number of images per month per scannerscanner
– GB per month per scannerGB per month per scanner
Archiving strategy at Archiving strategy at MUSCMUSC Archive everythingArchive everything Better data integrityBetter data integrity
– Validated against the Validated against the RIS RIS
– Full data set archivedFull data set archived– Can retrospectively Can retrospectively
reconstruct any study reconstruct any study without date limitswithout date limits
More storage More storage consumptionconsumption– Increased archival Increased archival
costscosts– Increased Increased
transmission and transmission and retrieval timesretrieval times
PACS Workflow Manager
Recon WorkstationReading Area 2
Recon WorkstationReading Area 1
Thin Client Server
DIC
OM CT Studies
AutoRouted
Query/Retrieve
Thin Clients
20 Tb Disk Storage
2 Tb Disk Storage
Th
in S
lice
s
Full Data Set Storage
CT
Query/R
etrieve
Qu
ery
/Re
trie
ve
Notable time pointsNotable time points
CT scannersCT scanners– Upgraded from single to dual/quad Upgraded from single to dual/quad
slice scanners in 2000/2001.slice scanners in 2000/2001.– Dual/quad slice replaced with 16 slice Dual/quad slice replaced with 16 slice
in 2003.in 2003.– Replaced 1 16 slice with 64 slice, Replaced 1 16 slice with 64 slice,
added CT-Sim, 1 64 slice in added CT-Sim, 1 64 slice in 2004/2005.2004/2005.
– 1 16 slice replaced with dual source 1 16 slice replaced with dual source scanner in 2006.scanner in 2006.
Notable time pointsNotable time points
Converted to all digital Converted to all digital mammography in 2005 (4 units)mammography in 2005 (4 units)
3T MRI magnet (#4) added in 3T MRI magnet (#4) added in 20022002
Open MRI magnet (#5) added in Open MRI magnet (#5) added in 20052005
PET added in 2001. Upgraded to PET added in 2001. Upgraded to PET/CT-16 in 2006PET/CT-16 in 2006
Studies Per MonthStudies Per Month
Images Per MonthImages Per Month
Storage RequirementsStorage Requirements
Storage RequirementsStorage Requirements
Studies Per GBStudies Per GB
Images Per GBImages Per GB
Case Study: CRCase Study: CR
Relatively stableRelatively stable Majority of growth tends to come Majority of growth tends to come
from additional service locationsfrom additional service locations Large images, low volumeLarge images, low volume Generally used to dictate PACS Generally used to dictate PACS
requirementsrequirements
CR: Studies/MonthCR: Studies/Month
CR: Total CR: Total images/monthimages/month
CR: GB Per MonthCR: GB Per Month
Case Study: CTCase Study: CT
CT contributes most in terms of # of CT contributes most in terms of # of imagesimages
Small images but high volumeSmall images but high volume Majority of archive storage is now used Majority of archive storage is now used
for CT imagesfor CT images Increased use of 3D reconstructions Increased use of 3D reconstructions
and multi-planar reformats means and multi-planar reformats means studies containing 10 000 images are studies containing 10 000 images are now routinenow routine
CT: Studies/MonthCT: Studies/Month
CT: Studies/scannerCT: Studies/scanner
CT: Total CT: Total images/monthimages/month
CT: Average CT: Average Images/StudyImages/Study
CT: Max images/studyCT: Max images/study
CT: Average CT: Average GB/ScannerGB/Scanner
Case Study: Case Study: Technology changes in Technology changes in CTCT One physical CT scanner location One physical CT scanner location
analyzed from 1998 to 2006analyzed from 1998 to 2006 Outpatient settingOutpatient setting Location changed from single Location changed from single
slice to 16 slice to dual-source slice to 16 slice to dual-source scanner during this time periodscanner during this time period
Studies/monthStudies/month
Total images/monthTotal images/month
Images/study/monthImages/study/month
Case Study: MRICase Study: MRI
Few changes in technology aside Few changes in technology aside from additional scannersfrom additional scanners
Acquisition protocols tend to be Acquisition protocols tend to be relatively staticrelatively static
Changes in storage requirements Changes in storage requirements mostly due to increases in volumemostly due to increases in volume
MRI: Studies/MonthMRI: Studies/Month
MRI: Studies/ScannerMRI: Studies/Scanner
MRI: Total MRI: Total Images/MonthImages/Month
MRI: Average MRI: Average Images/StudyImages/Study
MRI: Max images/studyMRI: Max images/study
MRI: Average MRI: Average GB/ScannerGB/Scanner
Case Study: PET/CT Case Study: PET/CT
Started with dedicated PET Started with dedicated PET scanner shared with neighbouring scanner shared with neighbouring hospital in 2001hospital in 2001
Upgraded to non-shared PET/CT-Upgraded to non-shared PET/CT-16 in 200616 in 2006
Current PET/CT workload is 6-7 Current PET/CT workload is 6-7 patients/daypatients/day
Case Study: PET/CTCase Study: PET/CT
Data sent to PACSData sent to PACS– CT (3.75 mm slice thickness)CT (3.75 mm slice thickness)– Non-attenuation corrected PETNon-attenuation corrected PET– Attenuation corrected PETAttenuation corrected PET– Screen captures of axial, coronal, Screen captures of axial, coronal,
sagittal fused slicessagittal fused slices
PET/CT: Studies Per PET/CT: Studies Per MonthMonth
PET/CT: Images Per PET/CT: Images Per MonthMonth
PET/CT: Average PET/CT: Average Images Per StudyImages Per Study
PET/CT: GB Per MonthPET/CT: GB Per Month
Data RetentionData Retention
Using the GB/Month data, we can Using the GB/Month data, we can calculate how many months of calculate how many months of online storage a given size of disk online storage a given size of disk array can holdarray can hold
Can also calculate how large the Can also calculate how large the disk array must be to maintain N disk array must be to maintain N months of data onlinemonths of data online
Study RetentionStudy Retention
24 Month Retention24 Month Retention
Storage Storage ConsiderationsConsiderations
Changing storage Changing storage requirementsrequirements Changes significantly with Changes significantly with
widespread implementation of widespread implementation of MDCTMDCT
In the early days of PACS, CR In the early days of PACS, CR dominated storage requirementsdominated storage requirements
Major contributors to PACS storage Major contributors to PACS storage requirements are CR, CT, MR, MGrequirements are CR, CT, MR, MG– Make up about 98% of storage Make up about 98% of storage
requirements at MUSCrequirements at MUSC
Changing storage Changing storage requirementsrequirements Digital mammography has a large Digital mammography has a large
effect on storage requirementseffect on storage requirements– Low volume but very large imagesLow volume but very large images
Dynamic multi-frame data looked Dynamic multi-frame data looked at brieflyat briefly– Not a major contributor to storageNot a major contributor to storage– Currently ~10% of totalCurrently ~10% of total– US is the biggest contributorUS is the biggest contributor
Growth PatternsGrowth Patterns
MDCTMDCT– Exponential growth in CT images Exponential growth in CT images
during early phase as new protocols during early phase as new protocols are developed and implemented and are developed and implemented and scanner capabilities are exploredscanner capabilities are explored
– Growth rate expected to level off as Growth rate expected to level off as capacity is reached and scan capacity is reached and scan protocols establishedprotocols established
Predicting Storage Predicting Storage RequirementsRequirements Obtain monthly data on storage Obtain monthly data on storage
history (# images each month for CR, history (# images each month for CR, CT, MR, MG) for the past yearCT, MR, MG) for the past year
Estimate total storage per month Estimate total storage per month based on image file sizesbased on image file sizes
Examine data for trendsExamine data for trends Apply a realistic model (linear, Apply a realistic model (linear,
polynomial, power, exponential) to polynomial, power, exponential) to forecast future growthforecast future growth
Future NeedsFuture Needs
CR, CT, MR, MG are the Big 4CR, CT, MR, MG are the Big 4 Planning for future PACS archiving Planning for future PACS archiving
or archive expansion needs to or archive expansion needs to consider current storage trendsconsider current storage trends
MDCT and digital mammography MDCT and digital mammography places large demands on storage places large demands on storage and must be consideredand must be considered