1

1

วรงค โตเจริญชัยM.S. Electrical and Computer Engineering

2

References:http://www.sprawls.org/resourceshttp://www.sprawls.org/resources/DIGRAD/classroom.htm

3

2

1

3

4

5

6

7

4

Picture Archiving and Communication System (PACS)

5

CR/Modality/Digital Radiography

CR

1. Reader Unit

Imaging Plate

DICOM 3

PACS Server

2. Console (Image Processingand Registration computer)

6

2

7

Patient Registration

001

James เจมส

8

Workflow

Screen/Film CR (Digital)

9

Workflow

Screen/Film CR (Digital)

10

Patient Information System

1. Manual key in from the Console of Modalities

2. Query from the PACS worklist (need Modality Worklist)

การลงทะเบียนผูปวยจากระบบ HIS หรอื RIS ซ่ึงระบบดังกลาวจะสงขอมูลตามมาตรฐาน HL/7 ไปใหระบบ PACS เพ่ือให Modality สามารถดึงขอมูลการลงทะเบียนลวงหนา (modality worklist) ที่มีอยูในระบบ PACS มาใชได

11

Patient Information Work flow

Registration

Patient

1Register

2

Query/Retrieve

patient’s info.

7

X-ray

HIS Server

Doctor

3

See Doctor

4

Request X-Ray

X-Ray Registration RIS Server

5

Query/Retrieve

X-Ray exam.’s info.

6

Query/Retrieve info.

PACS Server

8

Store ImagesX-Ray CR/DR10

Query Images

9Query/Retrieve info.

11Query

Report

PACS Viewer

12

HIS

PACS/HIS/RIS CONNECTION

TEST SERVER

SERVER& RAID

SERVER& RAID

SERVER& RAID

Rack

RISorders

reports

DMWL

DICOM

RISReportorders

DICOM

reports

PACS RIS

Voice Recognition3D Reconstruction

MS Office

IHE - Integrated Health Enterprise

ImageReport

3

13 14

Patient Worklist

15

Patient Information and Image

Patient Information

(HN, Name, Age, etc.)

16

Patient Folder Hierarchy

Patient Folder

Study Folder

Series Folder

Images

Study Folder

Series Folder

Images

17 18

How to get Digital image ?

• Digital Detector• CR – Computed Radiography• DR – Digital Radiography

• Direct Digital Radiography• Indirect Digital Radiography

4

19

Detectors

20

Computed Radiography

Computed Radiography

21

Computed Radiography

Imaging PlateConsole

Reader Unit

22

CR Basics

Computed Radiography refers to the use of Photostimulable Storage Phosphors (PSP or Imaging Plate - IP) in image capture and subsequent image digitization for Projection Radiography applications.

Light Shielding Layer

Protective Laminate

Conductive Layer

Phosphor LayerBaF(BrI):EU2+

ID Barcode Label

Flexible support

Backing Layer

23

Phosphor material

Barium fluorohalide crystal with a trace of bivalent europium ionsBaFX:Eu2 , X=Cl, Br, I

•Exposure

•Instant luminescence

•Storage

•Stimulated luminescence

Imaging plate

50% after 24 hours

100%

50%

0%0 Hr 12 Hrs 24 Hrs

% L

umin

osity

Time

5

25

Imaging plate X-Ray tube

Reading Unit

Optical Scanner

LaserBeam

Erasingunit

Light

Principles Employed In Image Acquisition, Reading and Erasure

CR Image Acquisition

Exposure

Patient

Reading System of Storage Phosphor

A/D

Converter

Laser Beam

Imaging Plate

Optical Scanner

Photomultiplier Tube

Motor

27

Dual Side Reading

28

New Imaging Plate : for Pediatric and Mammogram

1. Thicker layer2. Transparent support

Imaging Plate forSingle Side Reading

Protect layer

PhosphorLayer

Base Layer

Imaging Plate forDual Side Reading

(Pediatric and Mammography)

Laser beam

3. Finer Grain Phosphor (↑sharpness)

29

Digital Radiography

(Direct) Digital Radiography30

6

31

Detectors

32

DR Detector Technology

1. CCD based systems (Indirect)2. Amorphous Silicon system (Indirect)3. Amorphous Selenium system (Direct)4. Phosphor + Line scan CCD (Indirect)

33

Detector technology:1. CCD based systems

A. Lens Coupling B. Fiber optic coupling C. multiple detectors

A phosphor screen converts X-rays into visual light that is projected onto a CCD or onto a CCD-array

source: www.dondickson.co.uk34

Light photon

X-ray photon

Scintillator

（2688 x 2688 pixel）43cm x 43cm

a-Si sensor

GOS (Gd2O2S:Tb)or CsI

Detector technology:2. Scintillator + Amorphous Silicon (A-Si)

35

Detector technology:2. Scintillator + Amorphous Silicon (A-Si)

36

Pixel size : 160μｍ x 160μｍ

Signal line Gate line Bias line

a-Si MIS-type photoelectric converter

a-Si TFT

Magnified Picture of a-Si sensor

1 Pixel

7

37

3. Photo Detector (Direct) - Amorphous Selenium

TopElectrode

Selenium

Thin filmtransistorarray

Glass Substrate

- - - -+ + ++

Read- out

Power supply

X-ray

38

3. Photo Detector (Direct) - Amorphous Selenium

39

Detector technology:4. Phosphor + Line scan CCD

Device IP

Scanning direction

Side View

Linear Laser SourceInline CCD (receives emitted light )

Line Scan

Light Collection Lens

Top View

40

Laser Diode

CCD Array

IP

Emitted Light

Line scan CCD Technology

Aluminum

Phosphor700μm

PETPhosphor

Focused Phosphor ST-VI

41

Detector technology: Summary

42

Detected Quantum Efficiency (DQE)

What is DQE ?

An expression of the efficiency of an image system’s transfer, from its input to its output, as a percentage of signal to noiseratio (SNR).

inputdetector at outputdetector at

2

2

SNRSNRDQE =

DQE is limited to ~70% in practice

8

43

DQE of detectors

DQE

44

DQE Comparison

source: www.dondickson.co.uk

45 46

Noise and Contrast

source: www.dondickson.co.uk

The detection of low contrast and high noise is a requirement

47

Detector Resolution/DQE

Highest

Medium

Lowest

Contrast resolution

DQESpatial resolution

Highest~80-150 micronDR

Medium50-100 micronCR

Lowest~25 micronScreen/Film

48

CR Technology

CR Advantages1. Superior flexibility and portability2. Existing x-ray system3. Lower cost than DR (Support multi-room)

CR Disadvantages1. There are cassettes to handle2. Longer image acquisition than DR3. Throughput

9

49

DR Technology

DR Advantages1. Short processing time and image acquisition2. No imaging plates or cassettes to hassle with3. Higher DQE (contrast)

DR Disadvantages1. More expensive than CR2. Mobile radiography necessitates a wire cable3. The imaging sensor is more expensive to replace 4. Replaced/modified existing x-ray equipment

50

Trends

CR • Faster throughput• Higher DQE

DR • Cheaper• Flexibility & Portability

Both technologies will probably coexist in future

51 52

Patient Worklist

53

Patient Folder Hierarchy

Patient Folder

Study Folder

Series Folder

Images

Study Folder

Series Folder

Images

HEADER (Information about image)

54

10

55

Matrix size VS File size

File size of a 128x128x8 bits image ?

128x128x1 byte = 16,384 bytes (16 kB)

8 bits1 2 3 ………. 128

12

128

3

.

.

.

12

8

56

Image VS File size

Image size increase 1 step (128 to 256)>> File size increase 4 times

128

256

512

512

1024

1024

256

57 58

Characteristic Curves

DigitalDetector

Screen/Film

105

104

103

102

101

100

10-110-2

1

2

3

100 101 102 103

Exposure mR

Film

Den

sity

Inte

nsity

rela

tive

of th

e lu

min

osity

60

Dynamic Range

11

61

10 Bit

SmaxSmin

Automatically detect bone to airand 10 bits are assigned

No Clinical InfoNo Clinical Info

12 Bit

Histogram Analysis

63

The value of each pixel and the number of times that the pixel value occurs in the image

Histogram Analysis

1 2 3 4 5S1

S2S3

S4S5

0

5(S1 and S2) are established to define the Lowest and

Highest areas of useful exposure as determined by the menu selection.

Bone Soft Tissues Skin Air

S1 S2Rel

ativ

e Fr

eque

ncy

X-Ray Dose ( Exposure)

Histogram Analysis : General

65 66

Internal Organs Skin Air

S1 S2

Spine

Histogram Analysis : Spine

12

67

Gastric

Barium Internal organs Skin Air

S1 S S2

Histogram Analysis : GI

68

Spine image : Spine Protocol

69

Spine image : Chest Protocol

70

Spine image : Hand Protocol

71

Low energy (kVp) gives a wider histogram

High energy (kVp) gives a narrow histogram

Histogram Analysis

Step wedge

72

Histogram width is controlled by the kVp and subject contrastThe lowest amount of exposure (Smin/S1) and highest (Smax/S2) are recorded

Histogram Analysis

13

It reflects the center of the usable portion of the histogram

Calibration is based on a 1 mR exposure at 80 kVp to the IP. Using a 72” distance through air to achieve an “S” number of 200 with a fixed

latitude “L” of 1.

“S” Number - Sensitivity

3 different mAs exposures (80kV)

The histogram shape is the same

The position on the exposure axis

changes.

“S” Number - Sensitivity

75

Scatter – Use of Grids Distance – SIDCollimationMenu selectionDelay in processing from time of exposure

Factors that affect “S” number

An “S” number under 75 is typically considered over exposure

Under exposure is generally represented by an “S” number greater than 500

“S” Number - Sensitivity

Chest, General 200-600 Chest, Port. 100-400

Skull 100-400 Abdomen 100-400

Spine 100-400 GI 100-300

Extremities 75-200

Chest, Pedi. 200-700 Abdomen, Pedi. 200-700

Typical “S” # Range

14

79

Anatomical menu selectionCenteringCollimationGrid used (subjects > 10 cm)Proper kVp range selectedCheck “S” number and “L” valueIP used or erased in past 48 hours

Image Quality Review

80

>10 cm

80 kVp

Day 1

Portable Chest - No Grid

81

Portable Chest – 6:1 Grid

Same Pt.

85 kVp

Day 2

82

You be the Judge

Day 1 Day 2

83

Images should not be critiqued by “S” number alone.

It is very important to view the whole image

Image Quality Review

84

Image ProcessingMulti-objective Frequency Processing (MFP)

MFPConventional

15

85

An enhancement coefficient can be set for each size structure.Image quality can be freely adjusted just like sound quality that can be adjusted freely with a graphic equalizer.

Sound Quality Adjustment (graphic equalizer)

Soun

d

Low Frequency High

Sound quality can be freely adjusted.Sounds above a certain frequency can be adjusted.

Conventional processing Multi-objective Frequency Processing

Large Structure Size Small

Image Quality Adjustment (frequency processing)

Small structures below a set size can be enhanced.

Image quality can be freely adjusted.

Low Frequency High

Soun

d

Res

pons

e

Res

pons

e

Large Structure Size Small

Enhancement Characteristic Optimization

86

Image ProcessingGradation and Frequency processing

Left side image(Stimulating F/S)

Right side image(Enhanced image)

87

Image ProcessingDynamic Range Control (DRC)

No DRC process DRC process

88

Image ProcessingGPR (Grid Pattern Removal)

Removes stationary grid pattern

89

ObjectiveSuppress noise in an image with minimum loss of diagnostic information (sharpness) while enhancing image quality.

Image ProcessingFNC : Flexible Noise Control

90

Noise component extraction

processing

Suppression coefficient (0.0

to 1.0)

Overview of Processing

Subtraction

Original image Noise-suppressed image

Noise components

Image ProcessingFNC : Flexible Noise Control

16

91

Com

bina

tion

Proc

essin

g

EdgeDetection

Processing

CalcificationPosition

DetectionProcessing

Calcification Edge

Information

OriginalImage

Detection of Centerof Calcification Image

Non-Calcification Edge

Image Processing - MammographyPattern Enhancement Mammography (PEM)

92

Image ProcessingEnergy subtraction

Original Image Soft Image Bone ImageDifferentiation between tumor and Calc.

93

Image ProcessingEnergy Subtraction

94

Energy Subtraction Principle

95 96

17

97 98

99 100

101 102

18

103 104

PACSServer Farm Doctor’s home

InternetInternet OPD2

OPD1Ward

Radiology Department

Enterprise PACS Network

Intranet

105 106

• LCD Monitor > 20” color or B/W (calibrated)• High resolution 3-15 Mega Pixels• High Brightness > 500 Cd/m2, Contrast Ratio > 600:1

• Need special display adapter or VGA Card• Consistent Image Quality and Medical Approval (FDA)

Diagnostic Display

107

Display Luminance (cd/m2) Controlled

• View Box ≥ 1000 No

• LCD Display 200 – 300 No(Consumer)

• LCD Display 500 – 1000 Yes(Medical grade)

Brightness or Luminance

108

Constant Luminance for the Life of the Display

600 cd/m2

6500 hours

500 cd/m2

17000 hours

700 cd/m2

2000 hours

800 cd/m2

200 hours

Maximum Luminance as a function of Runtime

50

55

60

65

70

75

80

85

90

95

100

1 10 100 1000 10000 100000

Backlight Operation (Hours)

Lum

inan

ce (%

)

LCD Vendor Data

19

109

SMPTE Pattern for testing monitor

110

111

Technology Selections

• Applications • Reading Speed (films/hour)• Resolution (pixels/mm)• Software /ease of use• Service and support

Energy Subtraction

CassetteLess

Compact General Chest Check upMammogram112

CR Conclusion

Image acquisition1. Imaging plate2. CR Reader unit3. Image processing computer (CR console)

113

DR Conclusion

Type of DR/Image acquisition1. CCD2. Amorphous Silicon3. Amorphous Selenium4. Phosphore + CCD

DQE (efficiency of detector)

Noise vs. Contrast

114

warong@jfav.co.th