di com basics

8/11/2019 Di Com Basics

1/78

DICOM

Basics forRadiographic and Fluoroscopic

SystemsS. Jeff Shepard, M.S.

Department of Imaging PhysicsUniversity of Texas M. D. Anderson Cancer Center

DICOM is the registered trademark of theNational Electrical Manufacturers Association forits standards publications relating to digitalcommunications of medical information.2004 AAPM Summer School2004 AAPM Summer School


2/78

2004 AAPM Summer School

DICOM for R&F Systems

DICOM Basics (Services, Objects, etc) DICOM Elements Essential to R/F

Networking Basics and Connectivity Assessing Functionality of DICOMServices on R/F Systems

Controlling the Quality of R/F ImagesUsing DICOM

The RFP for R/F Systems


3/78


DICOM BasicsOrganization Services Classes

Store

Print Query/Retrieve (Q/R)

Information Objects Modality work lists (MWL) Schedule lists

Status updates Images (CT, MR, RF, CR, DX, etc)


4/782004 AAPM Summer School

DICOM Basics Communication Event: Instance

Service-Object Pair (SOP) Store & RF Image (Store-RF) Print & DX image (Print-DX) Query/Retrieve & MWL (Q/R-MWL)

Service class Users and Providers Client is user

Server is provider


5/782004 AAPM Summer School

DICOM Basics

PACSService Class Provider (SCP)R/F systemService Class User (SCU) RF imageObject

StoreStore --RF SOPRF SOP


6/78


DICOM BasicsR/F systemSCUWork ListObjectRISSCP

Query Work ListQ/R MWL SOPQuery Work List

Retrieve Work ListRetrieve Work ListQ/R MWL SOPQ/R MWL SOP

Q/R MWL SOP


7/78


DICOM Basics DICOM

Storage Commitment Modality sends number of images in each

series PACS responds with failure message if all

are not received

Performed Procedure Step Modality informs RIS of exam begin/end

Problematic for multimodality exams


8/78


DICOM Basics

RFP (Conformance Statement) Supported SOPs (SCU)

Store (RF, XF) Print (RF, XF) Q/R Modality Work List Storage Commitment Performed Procedure Step (Optional)


9/78


DICOM Elements for R/F Viewing DICOM object header

information (Meta Data) PACS provides tools for examination DICOM tags (Group,Element)

(0008,1030) Exam description (0010,0010) Patient name (0018,1030) Protocol description (0028,0002) Samples per pixel


10/78


DICOM Elements for R/F Viewing header information

Presentation will depend on viewing tool Layered structure

Patient, Study information Consistent across all object types

Series, Image information Will depend on type of object


11/78


DICOM Elements for R/F Patient demographics

Patient Name

MRN DOB

Sex


12/78


DICOM Elements for R/F Image information Other Modalities(DX, CR, DR, etc)

Patient Dose Technique factors

Exposure Index Info. is specific to

modality type


13/78


Basic NetworkingAll devices must configured for TCP/IP (Transmission

Control Protocol / Internet Protocol)communications Host name

Identification to other machines IP Address

Internet Protocol address (xxx.xxx.xxx.xxx) xxx Octet (0 255)

Used by routers to route information packets(datagrams)


14/78


Basic Networking IP Address

May be fixed or assigned by a server Dynamic Host Configuration Protocol

(DHCP)

Host and IP may be required to

communicate Promiscuous mode if not required

DHCP is contraindicated for operation with PACS and RIS (non-promiscuous)


15/78


16/78


Basic Networking

Subnet Mask Defines the class of the devices

communications (router, gateway or client) Identifies which devices require traffic to be

routed through a gateway Netmask =255.255.255.0 means that any

devices on the subnet with the same first three

IPs can communicate directly without goingthrough a router (Class C operation)


17/78


Basic Networking

for DICOM Port #

Logical endpoint for connection Specific to type of activity (104

common for DICOM) Different SCs may use different ports

on same device


18/78


Basic Networking

for DICOM Application Entity Title (AE Title

or AET) Unique device name used for a

particular DICOM service on a device(like a password)

May have several for different serviceclasses (ct5 for Store,

PR-ct5_SCU for Print)


19/78


Basic Networking

for DICOM

Host table List of aliases used by applications

IP, AET and Port of all other DICOMdevices


20/78


21/78


22/78


Assessing Functionality Elements in the header affect:

Patient Identification (RIS) Image Quality (PACS and Print)

Hanging Protocols (PACS) Functional assessment consists of

assuring that the tags are preservedduring transmission and are properly

applied by the PACS, RIS, and printer.


23/78


24/78


25/78


26/78

Assessing Network Functionality

N

Correct IP, gateway,& mask configuration

on modality

Check IP, gateway, & mask configuration

N

Correct?Y Contact

network administrator

Ping Gateway

Successful?

Y


27/78


Y Contactnetwork

administrator

Ping PACS,RIS, Print

Successful?

Y

N

CorrectPACS, RIS, PrintIPs on modality

NCheck

PACS, RIS, PrintIPs on modality

Correct?

Failed toContact host

k l


28/78

Assessing Network FunctionalitySend image to PACS

(or request Association)

Successful?

Y

YVerify

configuration withPACS administrator

N

Correct PACShost, AET, and

port on modality

N

Check PACS

host, AET, and port on modality

Correct?

AssociationFailed


29/78


Assessing Functionality

Transmission speed and duplexoperation Speed : Baud rate (ie 10 Mbps or 100

Mbps) Duplex : Transmit/Receive mode

Full- (two-way) or half- (one-way only) Must be configured consistently on both

gateway and client

A i N k F i li


30/78


YContact network administrator to

check switch settings

Prompt?

Y


N

Correct baud rate& T/R mode

on modality

N Check baud rate& T/R modeon modality

Correct?

Send image to PACS

A i N k F i li


31/78

Assessing Network FunctionalitySend image to Print


Successful?

Y

N

Correct Printhost, AET, and

port on modality

N

Check Print


Correct?Y

Verify

configuration withnetwork administrator

A i N t k F ti lit


32/78

Assessing Network FunctionalityQuery RIS for worklist


Successful?

Y

N

Correct RIShost, AET, and

port on modality

N

Check RIS


Correct?Y

Verify

configuration withnetwork administrator


33/78



With RIS Configure RIS with Host name, IP, AET, port #, and object type for the modality

RIS responds with appropriate list ofscheduled exams

For the device For a time interval

A i g RIS F ti lit


34/78

Assessing RIS Functionality

N

WL received?

Y

Request worklist

Start

Check RIS host,

WLM AET and port on modality

Correct?

N

Correct RIS host,WLM AET and

port on modality

Y

Contact RIS

administrator to check modality configuration

on RIS



35/78


Correct listreceived?

Y

N Check

Sched. Sta. AETon modality

Correct?

N

CorrectSched. Sta. AET

on modality

Backto start

Y

Contact RIS

administrator to check modality configuration

on RIS


36/78


37/78



With PACS PACS configuration

Modality host, AET, IP, and port

Check: Correct Patient and study demographics Series and Study descriptions (Hanging

protocols) Extract from study name from RIS, if possible


38/78



With PACS (contd) Multi-Frame Verify that images can be sent one per series or

multiple images per series (multi-frame) Combining multiple single-image series into one

multi-frame series allows viewing in stack-mode Important for R/F studies (facilitates navigation) Verify functionality if supported


39/78



With PACS (contd) Presentation State (electronic masks, image

flip, image rotate, image reversal, annotationsand LUTs)

Detector exposure indices (Pt. dose andnoise)

Patient dose indicator accuracy Pixel spacing (measurements in mm, not pixels)

Image Quality


40/78


Image Quality

(PACS)

If PACS workstation is designed to post-process raw images,

Verify post-processing parameters are present in header Verify post-processing parameters are

applied properly by workstation

Image Quality


41/78


Image Quality

(PACS) Check header on PACS to verify:

Widow width (0028,1050) Window level or center (0028,1051)

Check that PACS applies modalityWW and WL

Turn off Modality Gamma on PACS

Image Quality


42/78


Image Quality

(PACS) LUT

Rescale Type (0028,0054) = US Rescale Slope (0028,0053) Rescale Intercept (0028,0052)

Apply W/L in DICOM tags at modality

to set filters appropriately

Image Quality


43/78


Image Quality

(PACS) Compare LUT on QC monitor to PS 3.14

Measure steps on the QC monitor with a photometer (See TG18)

Calculate JNDs at min and max L for themonitor (PS 3.14, Table B1)

Calculate target JNDs at each step assuming a

linear increase with pixel value Calculate JNDs at each step from measuredvalues

Calculate % of total JND range at each step Compare to DICOM at each step

Display Calibration


44/78

0

20

40

60

80

100

120

140

0 200 400 600 800 1000

Digital Driving Level

L u m

i n a n c e

( C d / m

2 )

QC DICOMJND Index

QC DICOMJND Index

QC DICOMJND IndexLuminance

ddl QC QC DICOM% JND

Error


45/78

512

488

464

440

416

390366

342

318

294

271

246

223199

174

149

125

105

512 512

488

464

440

416

390366

342

318

294

271

246

223199

174

149

125

105 105

512 512

488 488464 464440 440416 416390 392366 368342 345

318 321294 296271 273246 249

223 225199 201174 177149 153125 129105 105

1023 130

963.0 109.0903.0 91.2842.0 75.9782.0 63.0722.0 51.0662.0 41.9602.0 34.2

542.0 27.6481.0 22.2421.0 17.7361.0 13.7

301.0 10.7241.0 8.1181.0 5.9120.0 4.260.0 2.90.0 2.04

100% 100%

94% 94%88% 88%82% 82%76% 76%70% 71%64% 65%58% 59%

52% 53%47% 47%41% 41%35% 35%

29% 29%23% 24%17% 18%11% 12%5% 6%0% 0%

0%0%0%0%-1%-1%-1%

-1%0%0%-1%

0%-1%-1%-1%-1%


46/78


47/78

Display Calibration


48/78


0

100

200

300

400

500

600

0 200 400 600 800 1000

Pixel Value (DDL)

L u m

i n a n c e

( C d / m 2 )

QC

Display Calibration


49/78


200

300

400

500

600

700

800

0 200 400 600 800 1000

Pixel Value (DDL)

J N D

I n d e x

QCLinear (DICOM)

Display Calibration


50/78

0

50

100

150

200

250

300

0 200 400 600 800 1000

Pixel Value (DDL)

L u m

i n a n c e

( C d / m

2 )

QC


51/78

Image Quality


52/78


g Q y

(PACS) Calibrated QC monitors are rare

Include requirement for calibration to theBarten standard in DICOM PS 3.14 in the

RFP Pressure vendors to comply (With-hold final

payment until requirement is fulfilled?)

Image Quality


53/78


g Q y

(PACS) In the event of mismatch (> +10%)

QC console monitor may not be calibrated to sameLUT as PACS

Require calibration in RFP

Install DICOM calibration software yourself Information displayed on the QC console monitor

may be filtered (W/L or LUT) Information sent to PACS is ignored

May be incorrectly formatted (value representation)

PACS may improperly handle information

Image Quality:


54/78


(PACS)

Some (expensive) LCD monitorsSome (expensive) LCD monitorscorrect for this:correct for this:

BirefringentBirefringent filter layersfilter layers MultidomainMultidomain PixelsPixels InIn --Plane SwitchingPlane Switching

Combinations of above

ViewingViewing --angle dependence of brightnessangle dependence of brightnessand contrastand contrast

Asymmetries in molecular orientation within the

LC layer

90 O60 O30 O

Combinations of above


55/78


56/78

Image Quality


57/78


g y

(PACS) QC Console (display and graphics card)

Should match PACS calibration (within +10%) Preferably Barten

100:1 Contrast Ratio Resolution (at least 1280x1024) Off-axis contrast within +10% of center to

+15 O (horizontal) and +30 O (vertical) NO room light sensors

Require all in RFP

Image Quality


58/78


(PACS) Some systems are not designed to

display on GSDF-compliant monitors Adjust post-processing accordingly Specify PACS system in RFP and require

post-processing designed to display

correctly with the PACS display LUT .



59/78


(Hard Copy)

Printer configuration: Printer must apply appropriate LUT,D

min, D

max, sharpness, interpolation

and media type to be used Modality IP, Host, port, AET on print

server

Evaluate image quality

Image Quality


60/78


(Hard Copy) Elements that Control Image

Appearance on Printers D min /Dmax - must be identical on both

modality and printer May be omitted - use printer default

Addressable area (# rows and columns)on modality for true-size print

Margins and image box separation

Image Quality


61/78



Appearance on Printers Sharpness filter (Inverse Smoothness

filter) Smooth, Medium, Sharp Some printers apply edge enhancement

Magnification (Interpolation algorithm Replicate, Bilinear, or Cubic)

Media (Blue, Clear, Portrait, Landscape,

etc)

Image Quality


62/78


(Hard Copy) Elements that Control Image Appearance on

Printers LUT

Responsibility for Barten LUT - Printer orModality?

Set printer to linear LUT if modality appliesGSDF

Set printer to GSDF if modality sends linear LUT May require custom LUT to match modality

filter

Image Quality


63/78



Appearance on Printers Presentation State

LUT in a tag to be applied by printer Not yet supported by most modalities

Evaluate if supported

Image Quality


64/78


(Hard Copy) Send a digital step tablet image

(one-on-one) W/L settings Measure ODs of step tablet


65/78

Image Quality


66/78


(Hard Copy) Calculate the transmitted luminance from a

standard viewbox (~3000 Cd/m 2) Convert to JND indices (DICOM PS 3.14)

Calculate the %JND at each step Compare to the %JND at each step of the

PACS monitors Should be within +10%

p OD L0 0.16 1867.9

FilmFilm DICOM Error

100% 100%

%JNDJND

DICOM906

JND

DICOM906

JNDFilm906Film906Film906


67/78

68 0.28 1417136 0.42 1026.5205 0.56 743.64

273 0.69 551.27341 0.82 408.66409 0.95 302.94

477 1.09 219.46546 1.24 155.37614 1.39 109.99682 1.56 74.364750 1.72 51.447818 1.89 34.783887 2.13 20.015955 2.47 9.1488

1023 3.00 2.7

L = 2700 Cd/m 2 * 10 (-OD)

95% 93% 1%88% 87% 2%82% 80% 2%

76% 73% 3%71% 67% 4%65% 60% 5%

59% 53% 6%53% 47% 6%47% 40% 7%40% 33% 7%34% 27% 8%28% 20% 8%21% 13% 7%11% 7% 5%0% 0%121

854802749

697644592

540487435383330278225173121

864814766

721676632

585537489437391344284209121

864814766

721676632

585537489437391344284209121

864814766

721676632

585537489437391344284209121

Hard Copy Calibration

1000


68/78

100

200

300

400

500

600

700

800

900

1000

0 200 400 600 800 1000

Pixel Value (DDL)

%

J N D

FilmLinear (DICOM)

Image Quality


69/78


(Hard Copy) Measure density uniformity (5 places)

Measure distortion (regionally andglobally)

Geometric Distortion


70/78

Geometric Distortion


71/78


(Hard Copy)

Examine sharpnessof alpha-numericcharacters

Summary RFP


72/78


(Modality) Basic Networking

Access to all passwords for network andDICOM re-configuration.

Training and manuals necessary tosupport reconfiguration.

Network and DICOM configuration parameters should be password

protected!!!

Summary RFP


73/78


(Modality) DICOM

Supported SOPs (SCU) Store (RF, DX, XF)

CR devices should support DX objects,not CR

Manual send or Auto send (user

selectable) Print (RF, DX, XF)

Summary RFP


74/78


(Modality) DICOM

Q/R Modality Work List Query by Accession Number, Date, ID, or Name

Ad hoc and periodic

Storage Commitment


75/78

Image Quality


76/78


(Modality) QC Console (display and graphics card)

Calibration matches PACS within +10%(preferably DICOM PS3.14 GSDF)

100:1 Contrast Ratio (L max /Lmin) Resolution at least 1200x1600 pixels

Off-axis contrast within +10% of center to+15 O (horizontal) and +30 O (vertical) NO room light sensors

Summary RFP


77/78


(Modality) Other Manipulation of header information

content Interoperability with PACS

Tag information formatted, parsed

Private Tags (non-standard information)

Summary RFP


78/78


(Modality) Other:

Multi-frame objects Integration of multiple single-frame series into

one multi-frame object (for stack-modeviewing)

Support for overlay data (not burned in) Re-open exam and add images

di com basics

Documents