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ProgramProgram�� Monday:Monday:

•• The Role of the Physicist in the Planning and Design of The Role of the Physicist in the Planning and Design of Digital Image Management Systems Digital Image Management Systems

oo D Peck and M Flynn, Henry Ford Health SystemD Peck and M Flynn, Henry Ford Health System

�� Tuesday:Tuesday:•• Characteristics and Performance Evaluation of Digital Image Characteristics and Performance Evaluation of Digital Image

Displays Displays oo HH RoehrigRoehrig, University of Arizona, University of Arizona

�� Wednesday: Wednesday: •• Digital Image Processing in RadiographyDigital Image Processing in Radiography

oo DD FoosFoos, X Wang, Kodak Research Laboratories, X Wang, Kodak Research Laboratories

�� Thursday: Thursday: •• Design and Performance Characteristics of Digital Design and Performance Characteristics of Digital

Radiographic ReceptorsRadiographic Receptorsoo J Seibert, UC Davis Medical Center J Seibert, UC Davis Medical Center

The Role of the Physicist in the The Role of the Physicist in the Planning and Design of Digital Image Planning and Design of Digital Image

Management SystemsManagement Systems

Donald Peck, PhDDonald Peck, PhDandand

Michael Flynn, PhDMichael Flynn, PhD

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OutlineOutline

�� Part 1Part 1•• Digital image acquisition/modality options Digital image acquisition/modality options •• Modality integration Modality integration

�� Part 2Part 2•• Bandwidth and storage requirementsBandwidth and storage requirements•• Softcopy viewing requirementsSoftcopy viewing requirements•• Performance/QA monitorsPerformance/QA monitors

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Modality OptionsModality Options

�� Similar diagnosis can be done using different Similar diagnosis can be done using different modalitiesmodalities

•• Plane XPlane X--Ray/CTRay/CT•• Mammography/US/MRIMammography/US/MRI

�� All imaging studies can be done utilizing a digital All imaging studies can be done utilizing a digital acquisition systemacquisition system

�� Many studies can be performed using different Many studies can be performed using different detector systemsdetector systems

•• Storage Phosphor/DirectStorage Phosphor/Direct

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Modality RequirementsModality Requirements

�� Acquisition requirementsAcquisition requirements•• Spatial and Temporal resolutionSpatial and Temporal resolution

�� Backup/redundant systemsBackup/redundant systems•• Multiple cassette based systems vs. single direct radiography Multiple cassette based systems vs. single direct radiography

�� WorkflowWorkflow•• Can all views be obtained with the detector?Can all views be obtained with the detector?

oo Positioning, detector size, grid usage, etc.Positioning, detector size, grid usage, etc.

•• Direct radiography may allow increased productivityDirect radiography may allow increased productivity

�� CostsCosts

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Modality InstallationModality Installation

�� Site planningSite planning•• Shielding, HVAC, power, etc.Shielding, HVAC, power, etc.•• NetworkNetwork

oo # drops, bandwidth from modality, switch settings, etc.# drops, bandwidth from modality, switch settings, etc.

�� Communication standardCommunication standard•• HL7HL7

oo Primarily between HIS and RISPrimarily between HIS and RIS

•• DicomDicom

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DicomDicom�� Part 3: Information Object DefinitionsPart 3: Information Object Definitions

•• Image objectsImage objects•• NonNon--image objectsimage objects

�� Dicom elementsDicom elements•• Defines specific information about the objectDefines specific information about the object

oo Information stored in Information stored in ““TagsTags””

•• Requires specific value representation (VR) Requires specific value representation (VR) oo Structure/Format, Information order, etc.Structure/Format, Information order, etc.

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NonNon--Image Objects (33)Image Objects (33)

�� ST ST -- Stand Alone ObjectStand Alone Object�� OV OV ––OverlayOverlay�� CV CV –– CurveCurve�� Mod LUT Mod LUT –– Modality lookModality look--upup--tabletable�� VOI LUT VOI LUT –– ValueValue--ofof--interest lookinterest look--upup--tabletable�� PET CV PET CV –– PET CurvePET Curve

�� Basic Study DescriptionBasic Study Description�� Gray Scale Presentation StateGray Scale Presentation State�� Stored PrintStored Print�� Enhanced MREnhanced MR

�� SpectroscopySpectroscopy�� Raw DataRaw Data�� RT RT –– Radiation TherapyRadiation Therapy

�� DoseDose�� StructureStructure�� PlanPlan�� Beam RecordBeam Record�� BrachyBrachy RecordRecord�� SumSum

�� WF WF –– WaveformWaveform�� Basic Voice Audio Basic Voice Audio �� 12 Lead ECG 12 Lead ECG �� General ECGGeneral ECG�� Ambulatory ECGAmbulatory ECG�� HomodynamicHomodynamic�� Basic Card EPBasic Card EP

�� SR SR –– Structured ReportStructured Report�� Basic TextBasic Text�� EnhancedEnhanced�� ComprehensiveComprehensive�� Key Object SelectionKey Object Selection�� Mammography CADMammography CAD�� Chest CADChest CAD

Image Objects (26)� CR - Computed Radiography� CT - Computed Tomography� MR - Magnetic Resonance

� Enhanced MR� NM - Nuclear medicine� DX – Digital X Ray� US –Ultrasound

� MF - Multi-Frame � SC – Secondary Capture

� MF - Multi-Frame� SB - Single Bit� GB - Grayscale Byte� GW - Grayscale Word� TC - True Color

� XA –X Ray Angiography � RF – X Ray Fluoroscopy � RT - Radiation Therapy Image� PET – Positron Emission Tomography � DX – Digital Radiography� MG – Digital Mammography� IO – Digital Intra Oral� VL – Visible Light

� EN - Endoscopy� MC - Microscopic� SL - Slide� PH - Photographic

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Dicom HeaderDicom Header

�� Information utilization:Information utilization:•• Determine acquisition system and Determine acquisition system and

locationlocation•• Radiographic technique QARadiographic technique QA•• Dose determinationDose determination•• Setup display annotationsSetup display annotations•• Verify acquisition or processing Verify acquisition or processing

parameters usedparameters used

�� Private TagsPrivate Tags•• Used for proprietary or vendor Used for proprietary or vendor

specific informationspecific information•• may not be visiblemay not be visible

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What Does a Physicist Need to KnowWhat Does a Physicist Need to Know

�� What elements does Modality populate?What elements does Modality populate?•• Majority of elements are optionalMajority of elements are optional

oo Dicom committee knows more mandatory elements need Dicom committee knows more mandatory elements need to be included in future standardto be included in future standard

�� What elements can PACS use?What elements can PACS use?•• Many optional elements are not supported by PACSMany optional elements are not supported by PACS

�� Is Modality supporting current and/or Is Modality supporting current and/or ““retiredretired””object standard?object standard?

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Example: CT/MR ObjectExample: CT/MR Object�� Originally developed over 10 years agoOriginally developed over 10 years ago�� New objects include advanced features:New objects include advanced features:

•• MultiMulti--slice dataslice data•• Specialized data interchange and archivingSpecialized data interchange and archiving

oo Raw data storageRaw data storageoo Post processed data handlingPost processed data handling

MRIMRICTCT

949410310339394141New StandardNew Standard224444001818Original StandardOriginal Standard

Mandatory Mandatory ElementsElements

Total Total ElementsElements

Mandatory Mandatory ElementsElements

Total Total ElementsElements

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Dicom Modality Worklist Dicom Modality Worklist (DMWL)(DMWL)

�� Defines transfer of information from Radiology Defines transfer of information from Radiology Information System (RIS) to ModalityInformation System (RIS) to Modality

�� DMWL Elements (over 50) DMWL Elements (over 50) •• (0040,0002)(0040,0002) Scheduled Procedure Step Start Date Scheduled Procedure Step Start Date •• (0040,0003)(0040,0003) Scheduled Procedure Step Start TimeScheduled Procedure Step Start Time•• (0040,0007)(0040,0007) Scheduled Procedure Step DescriptionScheduled Procedure Step Description•• (0008,0050)(0008,0050) Accession NumberAccession Number•• (0010,0010)(0010,0010) PatientPatient’’s Names Name•• (0010,0020)(0010,0020) Patient IDPatient ID•• (0008,0060)(0008,0060) ModalityModality

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Workflow Workflow –– Pre PACSPre PACS

Obtain Patient

Patient ManagementInformation Management Image Processing

RIS Scheduled Study

RIS Forms Print

Study Folder Prep.

Reload/retrieve CR Cassettes

Submit for processing

Review Films

File & send folder

�1

�2

�3

�4

�5

�6

�7

�8

�9

�10

? repeats

RIS exam complete

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Position Patient

Acquire Image

Select, window and print images

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Workflow Workflow –– Fully Functional PACSFully Functional PACS

QC and send

PPS exam compl.

Modal. Worklist

Obtain Patient

Patient ManagementInformation Management Image Processing

RIS Scheduled Study

RIS Forms Print

Study Folder Prep.

Reload/retrieve CR Cassettes

Submit for processing

Review Images

File & send folder

�1 �2

�3

�4

�5

�6

�7? repeats

RIS exam complete

Modality Worklist

Position Patient

Acquire Image

X

PerformedProcedure Step

Select, window and print images

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New FeaturesNew Features

�� Scheduled Procedure Step Description Scheduled Procedure Step Description •• Institution generated description of study Institution generated description of study

�� Stores a description or classification that is used Stores a description or classification that is used at a local levelat a local level

•• Can allow integration of xCan allow integration of x--ray generator control to ray generator control to be preset for scheduled exams/viewsbe preset for scheduled exams/views

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Utilization by ModalityUtilization by Modality�� For each study received For each study received

from DMWL an icon or from DMWL an icon or listing of each ordered listing of each ordered view is displayed view is displayed

•• e.g. AP and Late.g. AP and Lat

�� For each listed view the For each listed view the appropriate technique is appropriate technique is automatically set:automatically set:

•• kVpkVp•• mAmA•• time/AECtime/AEC

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Image Storage and DisplayImage Storage and Display�� Modalities may acquire, Modalities may acquire,

locally store and send data locally store and send data differentlydifferently

•• Raw Raw –– ““For ProcessingFor Processing””•• Processed Processed -- ““For PresentationFor Presentation””

�� For CR/DX Objects, values For CR/DX Objects, values sent can be variedsent can be varied

•• 88 –– 12 bit12 bit•• Optical Density (OD)Optical Density (OD)•• Presentation values (PPresentation values (P--values)values)•• Log (exposure)Log (exposure)

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OD values OD values �������� FilmFilmImage values intended for Image values intended for film are printed to optical film are printed to optical

densitiesdensities

Image Value Optical Density

4000

1000

2000

3000

0

1.0

2.0

3.0OD

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OD values OD values �������� SoftcopySoftcopyOD values presented on a OD values presented on a

softcopy display have a softcopy display have a luminance ratio of ~350luminance ratio of ~350

Image Value Log(luminance)1 to 350 cd/m2

4000

1000

2000

3000

350

35

3.5

OD

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OD values OD values �������� SoftcopySoftcopyTo allow OD values presented on To allow OD values presented on a softcopy display to have a similar a softcopy display to have a similar appearance to film, window/level appearance to film, window/level

must be usedmust be used

Image Value Log(luminance)1 to 350 cd/m2

4000

1000

2000

3000

OD

350

35

3.5

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OD values OD values �������� SoftcopySoftcopyTo see dark regions of To see dark regions of image the window level image the window level

can be changedcan be changed

Image Value Log(luminance)1 to 350 cd/m2

4000

1000

2000

3000

OD

350

35

3.5

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Luminance responseLuminance responsesoftcopy vs. filmsoftcopy vs. film

�� OD values sent to film produce a luminance response with OD values sent to film produce a luminance response with log(luminance) proportional to image valuelog(luminance) proportional to image value

�� DICOM calibrated display characteristics produce a response DICOM calibrated display characteristics produce a response with increased contrast in darker portions of imagewith increased contrast in darker portions of image

0.1

1

10

100

1000

0 100 200 300 400 500 600 700 800

Lum

inan

ce(c

d/m

2 )

P value (JND index)

DICOMCalibratedresponse

Film, OD

Softcopy

OD values sent to a calibrated display produce

increased brightness and

decreased contrast in

darker regions

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Modality OutputModality Output

�� Modalities should be configured to send OD Modalities should be configured to send OD values to a printer and Pvalues to a printer and P--values to PACS values to PACS

�� If printing is done by PACS only, modalities If printing is done by PACS only, modalities should be setup to send Pshould be setup to send P--values onlyvalues only

•• PACS needs to send OD values to printerPACS needs to send OD values to printer•• Printers may be able to take PPrinters may be able to take P--values and map these values and map these

to OD values prior to printingto OD values prior to printing

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Image VOIImage VOI(CR/DX Objects)(CR/DX Objects)

�� Image processing algorithms determine specific value Image processing algorithms determine specific value of interest (VOI) range for data of interestof interest (VOI) range for data of interest

�� Log (exposure) values are converted to OD or P values Log (exposure) values are converted to OD or P values using a Look Up Table (LUT) using a Look Up Table (LUT)

Raw Image Value Stored Image Value0

4000VOI

LUT

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Application of VOI/LUTApplication of VOI/LUT

Raw Image Value

4000

1000

2000

3000

VOI

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Window/Level with preWindow/Level with pre--set set VOI/LUTVOI/LUT

Image Value

VOI

1000Window/Level

Setting

4000

3000

2000

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The DICOM VOI LUT sequenceThe DICOM VOI LUT sequence

�� Instead of storing data after VOI/LUT is applied, Instead of storing data after VOI/LUT is applied, modality modality ““maymay”” be able to send Presentation Values be able to send Presentation Values and VOI/LUT information in Dicom Headerand VOI/LUT information in Dicom Header

Raw image values P- values

VOI/LUT

1000

4000

2000

3000

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The DICOM VOI LUT sequenceThe DICOM VOI LUT sequence

�� Instead of storing data after VOI/LUT is applied, Instead of storing data after VOI/LUT is applied, modality modality ““maymay”” be able to send Presentation Values be able to send Presentation Values and VOI/LUT information in Dicom Headerand VOI/LUT information in Dicom Header

Raw image values P- values

VOI/LUT

1000

4000

2000

3000

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Application of VOI/LUTApplication of VOI/LUT

Raw Image Value

4000

1000

2000

3000

VOI

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Using VOI/LUTUsing VOI/LUT

Raw Image Value

4000

1000

2000

3000

VOI

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The DICOM VOI LUT sequenceThe DICOM VOI LUT sequence

�� Configuring CR/DX modality to send Configuring CR/DX modality to send VOI/LUT removes the need for applying VOI VOI/LUT removes the need for applying VOI and and ““removingremoving”” acquired informationacquired information

�� Requires PACS to apply and vary the VOI/LUT Requires PACS to apply and vary the VOI/LUT on the softcopy display workstation in real timeon the softcopy display workstation in real time