Program
Monday:
•
The Role of the Physicist in the Planning and Design of
Digital Image Management Systems
o
The Role of the Physicist in the
Planning and Design of Digital Image
Management Systems
D Peck and M Flynn, Henry Ford Health System
Tuesday:
•
Characteristics and Performance Evaluation of Digital Image
Displays
o
H Roehrig,
Roehrig, University of Arizona
Wednesday:
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Donald Peck, PhD
and
Michael Flynn, PhD
Digital Image Processing in Radiography
o
D Foos,
Foos, X Wang, Kodak Research Laboratories
Thursday:
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Design and Performance Characteristics of Digital
Radiographic Receptors
o
J Seibert, UC Davis Medical Center
1
Outline
Modality Options
Similar diagnosis can be done using different
modalities
Part 1
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Digital image acquisition/modality options
Modality integration
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•
Part 2
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Plane XX-Ray/CT
Mammography/US/MRI
All imaging studies can be done utilizing a digital
acquisition system
Many studies can be performed using different
detector systems
Bandwidth and storage requirements
Softcopy viewing requirements
Performance/QA monitors
•
3
Storage Phosphor/Direct
4
1
Modality Requirements
Modality Installation
Acquisition requirements
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Site planning
Spatial and Temporal resolution
•
Backup/redundant systems
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Multiple cassette based systems vs. single direct radiography
o
Workflow
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Can all views be obtained with the detector?
•
Direct radiography may allow increased productivity
o
Shielding, HVAC, power, etc.
Network
# drops, bandwidth from modality, switch settings, etc.
Communication standard
Positioning, detector size, grid usage, etc.
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HL7
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Dicom
o
Costs
Primarily between HIS and RIS
5
6
Image Objects (26)
Dicom
CR - Computed Radiography
CT - Computed Tomography
MR - Magnetic Resonance
Enhanced MR
Part 3: Information Object Definitions
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•
NM - Nuclear medicine
DX – Digital X Ray
Image objects
NonNon-image objects
US –Ultrasound
MF - Multi-Frame
SC – Secondary Capture
MF - Multi-Frame
SB - Single Bit
Dicom elements
•
GW - Grayscale Word
Defines specific information about the object
o
•
GB - Grayscale Byte
TC - True Color
XA –X Ray Angiography
Information stored in “Tags”
Tags”
RF – X Ray Fluoroscopy
RT - Radiation Therapy Image
Requires specific value representation (VR)
o
PET – Positron Emission Tomography
DX – Digital Radiography
Structure/Format, Information order, etc.
MG – Digital Mammography
IO – Digital Intra Oral
VL – Visible Light
EN - Endoscopy
MC - Microscopic
7
SL - Slide
PH - Photographic
NonNon-Image Objects (33)
ST - Stand Alone Object
OV –Overlay
CV – Curve
Mod LUT – Modality looklook-upup-table
VOI LUT – ValueValue-ofof-interest looklook-upup-table
PET CV – PET Curve
Basic Study Description
Gray Scale Presentation State
Stored Print
Enhanced MR
Spectroscopy
Raw Data
RT – Radiation Therapy
Dose
Structure
Plan
Beam Record
Brachy Record
Sum
WF – Waveform
Basic Voice Audio
12 Lead ECG
General ECG
Ambulatory ECG
Homodynamic
Basic Card EP
SR – Structured Report
Basic Text
Enhanced
Comprehensive
Key Object Selection
Mammography CAD
Chest CAD
8
2
Dicom Header
What Does a Physicist Need to Know
Information utilization:
What elements does Modality populate?
Determine acquisition system and
location
Radiographic technique QA
Dose determination
Setup display annotations
Verify acquisition or processing
parameters used
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•
•
•
•
•
o
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Many optional elements are not supported by PACS
Is Modality supporting current and/or “retired”
retired”
object standard?
Used for proprietary or vendor
specific information
may not be visible
•
Dicom committee knows more mandatory elements need
to be included in future standard
What elements can PACS use?
Private Tags
•
Majority of elements are optional
9
10
Dicom Modality Worklist
(DMWL)
Example: CT/MR Object
Originally developed over 10 years ago
New objects include advanced features:
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Defines transfer of information from Radiology
Information System (RIS) to Modality
DMWL Elements (over 50)
MultiMulti-slice data
Specialized data interchange and archiving
o
o
Raw data storage
Post processed data handling
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CT
•
MRI
Total
Elements
Mandatory
Elements
Total
Elements
Mandatory
Elements
Original Standard
18
0
44
2
New Standard
41
39
103
94
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11
(0040,0002)
(0040,0003)
(0040,0007)
(0008,0050)
(0010,0010)
(0010,0020)
(0008,0060)
Scheduled Procedure Step Start Date
Scheduled Procedure Step Start Time
Scheduled Procedure Step Description
Accession Number
Patient’
Patient’s Name
Patient ID
Modality
12
3
Workflow – Pre PACS
Patient Management
Information Management
4
1
Obtain Patient
RIS Scheduled
Study
2
RIS Forms Print
3
5
9
11
6
7
? repeats
X
Image Processing
Position Patient
Acquire Image
Study Folder Prep.
Workflow – Fully Functional PACS
8
Patient Management
Information Management
1
Submit for
processing
2
Obtain Patient
RIS Scheduled
Study
3 Modality
Modal.Worklist
Worklist
Reload/retrieve CR
Cassettes
RIS Forms Print
4
? repeats
PPS
exam compl.
File & send folder
File & send folder
8
6
Position Patient
Acquire
Image
QC and
send
Study Folder Prep.
Review Films
Image Processing
5
7
Submit for
processing
Reload/retrieve CR
Cassettes
Review Images
Performed
Procedure Step
10
12
RIS exam complete
Select, window and
print images
13
RIS exam complete
New Features
For each study received
from DMWL an icon or
listing of each ordered
view is displayed
Institution generated description of study
Stores a description or classification that is used
at a local level
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14
Utilization by Modality
Scheduled Procedure Step Description
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Select, window and
print images
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e.g. AP and Lat
For each listed view the
appropriate technique is
automatically set:
Can allow integration of xx-ray generator control to
be preset for scheduled exams/views
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•
•
15
kVp
mA
time/AEC
16
4
OD values
Image Storage and Display
Image values intended for
film are printed to optical
densities
Modalities may acquire,
locally store and send data
differently
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4000
Raw – “For Processing”
Processing”
Processed - “For Presentation”
Presentation”
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2.0
2000
8 – 12 bit
Optical Density (OD)
Presentation values (P(P-values)
Log (exposure)
1.0
1000
17
OD values
Image Value
Softcopy
Optical Density
18
Softcopy
To allow OD values presented on
a softcopy display to have a similar
appearance to film, window/level
must be used
4000
OD
3000
OD
3000
3.5
3.5
2000
2000
35
35
1000
Image Value
0
OD values
OD values presented on a
softcopy display have a
luminance ratio of ~350
4000
3.0
OD
3000
For CR/DX Objects, values
sent can be varied
•
Film
1000
Log(luminance)
1 to 350 cd/m2
350
Image Value
19
Log(luminance)
1 to 350 cd/m2
350
20
5
OD values
Luminance response
softcopy vs. film
Softcopy
To see dark regions of
image the window level
can be changed
4000
OD
OD values sent to film produce a luminance response with
log(luminance) proportional to image value
DICOM calibrated display characteristics produce a response
with increased contrast in darker portions of image
3.5
Luminance (cd/m2)
3000
35
2000
1000
350
Image Value
Log(luminance)
1 to 350 cd/m2
1000
100
10
Film, OD
100
200
300
400
500
P value (JND index)
600
700
800
OD values sent
to a calibrated
display produce
increased
brightness and
decreased
contrast in
darker regions
21
22
Image VOI
(CR/DX Objects)
Image processing algorithms determine specific value
of interest (VOI) range for data of interest
Log (exposure) values are converted to OD or P values
using a Look Up Table (LUT)
Modalities should be configured to send OD
values to a printer and PP-values to PACS
If printing is done by PACS only, modalities
should be setup to send PP-values only
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Softcopy
1
0.1
0
Modality Output
•
DICOM
Calibrated
response
PACS needs to send OD values to printer
Printers may be able to take PP-values and map these
to OD values prior to printing
VOI
4000
LUT
23
Raw Image Value
0
Stored Image Value
24
6
Window/Level with prepre-set
VOI/LUT
Application of VOI/LUT
4000
VOI
4000
VOI
3000
3000
2000
2000
1000
Window/Level
1000
Setting
Raw Image Value
Image Value
25
The DICOM VOI LUT sequence
26
The DICOM VOI LUT sequence
Instead of storing data after VOI/LUT is applied,
modality “may”
may” be able to send Presentation Values
and VOI/LUT information in Dicom Header
Instead of storing data after VOI/LUT is applied,
modality “may”
may” be able to send Presentation Values
and VOI/LUT information in Dicom Header
4000
4000
3000
3000
VOI/LUT
VOI/LUT
2000
2000
Raw image values
1000
P- values
Raw image values
27
1000
P- values
28
7
Application of VOI/LUT
VOI
Using VOI/LUT
4000
VOI
4000
3000
3000
2000
2000
1000
1000
Raw Image Value
Raw Image Value
29
30
The DICOM VOI LUT sequence
Configuring CR/DX modality to send
VOI/LUT removes the need for applying VOI
and “removing”
removing” acquired information
Requires PACS to apply and vary the VOI/LUT
on the softcopy display workstation in real time
31
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