Performance Comparison of Different DR Detectors Using Simplified - - PowerPoint PPT Presentation

Performance Comparison of Different DR Detectors Using Simplified eDQE Approach Dogan Bor1, Ahmet Guven2, Turan Olgar1, Ozlem Birgul2

1 Ankara University, Faculty of Engineering, Department of Physics Engineering 2 Ankara University, Institute of Nuclear Sciences, Department of Medical Physics.

OBJECTİVE

Simplification of eDQE formalism by excluding the beam stop measurements Comparison of different system performance in terms of eDQE Use of eDQE for the optimization of clinical image qualities

DETECTIVE QUANTUM EFFICIENCY-DQE

RQA Beam quality

Detector

0,2 0,4 0,6 0,8 1

1 2 3 4 MTF

freq (mm-1)

1,0E-07 1,0E-06 1,0E-05 1,0E-04

1 2 3 4 NNPS

freq(mm-1)

0,2 0,4 0,6 0,8

1 2 3 4 DQE

freq(mm-1)

*IEC-62220-1

W Edge phantom 10x10x1 mm

Ion Chamber

DQE (f) = MTF(f)2 NNPS (f) . K.q

Physical performance of the detector

EFFECTIVE DETECTIVE QUANTUM EFFICIENCY- EDQE-

0,2 0,4 0,6 0,8 1

1 2 3 4 eMTF freq(mm-1)

1,0E-07 1,0E-06 1,0E-05 1,0E-04

1 2 3 4 eNNPS freq(mm-1)

*Samei et al Med. Phys. 2009

Detector Grid 10:1, 40 lp/mm

0,05 0,1 0,15 0,2 1 2 3 4 eDQE freq(mm-1)

Ion Chamber

eDQE (f) = MTF(f)2 (1 – SF)2 NNPS (f) . TF. K.q

Performance of the system as a whole

INCLUSION OF SCATTER DATA TO THE MTF

Use of Beam Stop Technique

SF = PVAtten. PVBackg.

0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1 0,5 1 1,5 2 2,5 3 3,5 4 MTF freq(mm-1)

MTF no scatter

MTF x (1-SF)

• 0,2

0,2 0,4 0,6 0,8 1

• 30
• 20
• 10

10 20 30

LSF for different ROI size

50mm 40mm 30mm 20mm 10mm 0,2 0,4 0,6 0,8 1 0,5 1 1,5 2 2,5 3 3,5 MTF freq(mm-1)

10mm(roi) 20mm(roi) 30mm(roi) 40mm(roi) 50mm(roi)

INCLUSION OF SCATTER DATA TO THE MTF

NHSBSP OBJ_IQ (NW. Marshall)

• No truncation and windowing of LSF
• Include all the tail of LSF with a large ROI
• No normalization of the zero frequenc to unity for MTF

0,2 0,4 0,6 0,8 1 1 2 3 MTF freq(mm-1)

10cm PMMA

0,2 0,4 0,6 0,8 1 1 2 3 MTF freq(mm-1) 25cm PMMA 0,2 0,4 0,6 0,8 1 2 3 eDQE freq(mm-1) 10cm PMMA 0,2 0,4 0,6 0,8 1 2 3 eDQE freq(mm-1) 25cm PMMA

SF = 0.38

SF = 0.44

Increasing ROI size (mm) 10 20 . . 70

COMPARISON OF TWO TECHNIQUE

Systems Kodak DRX-1 Kodak DRX-1C Toshiba FDX4343R Philips l Pixium 4600 Conversion phosphor Gd2O2S:Tb CsI CsI CsI Pixel area 35x43cm 43x43cm 43x43cm Pixel matrix 2544x3056 3072x2560 3008x3072 3001x3001 Pixel pitch 139µm 143µm 143µm Grid type Stationary Stationary Moving Grid ratio 10:1 12:1 12:1 Focal spot size(mm) 2.0 1.2 1.2 1.2

TECHNICAL CHARACTERISTICS OF THE FOUR SYSTEM EVALUATED

90 kVp, 25 cm PMMA, AEC control, AK measurements in the Bucky

ACQUISITION GEOMETRIES

IEC Methodology Low scatter, focus unsharpness (G2) Scatter + focus un harpness (G3) Beam hardening filtering (G1)

SIGNAL TRANSFER PROPERTY-STP

1,0E+02 1,0E+03 1,0E+04 1,0E+05 0,0 5,0 10,0 15,0 Pixel value (Log axes) Detector Dose(uGy)

STP-RQA7(IEC geometri)

DRX-1C DRX-1 Toshiba Pixium 4600 1,00E+02 1,00E+03 1,00E+04 1,00E+05 0,00 2,00 4,00 6,00 8,00 10,00 Pixel value (Log axes) Detector Dose(uGy)

STP-90kVp_G1

DRX-1C DRX-1 Toshiba Pixium 4600

Signal Transfer Properties Functions Systems RQA Geometry G1 Geometry DRX-1C y=435.62ln(K)+1166 y=515.71ln(K)+947.45 DRX-1 y=442.29ln(K)+1180.9 y=416.89ln(K)+1071.6 Toshiba FDX4343R y=164.83K+53.535 y=144.87K+56.106 Pixium 4600 y=2509.9ln(K)+14450 y=2560.8ln(K)+14593

MTF RESULTS FOR DIFFERENT DIGITAL RADIOGRAPHY SYSTEMS

0,0 0,2 0,4 0,6 0,8 1,0

1 2 3 4 5 MTF freq(mm-1)

DRX-1C(4.99µGy) DRX-1(4.7µGy) FDX4343R(4.7µGy) Pixium 4600-II(6.44µGy)

RQA7 G3 G1

0,0 0,2 0,4 0,6 0,8 1,0 1 2 3 4 5 eMTF freq(mm-1)

DRX-1C(4.87µGy) DRX-1(4.39µGy) FDX4343R(5.4µGy) Pixium4600-II(8.16µGy)

0,2 0,4 0,6 0,8 1 1 2 3 4 5 MTF freq(mm-1)

DRX-1C(5.64µGy) DRX-1(5.17µGy) FDX4343R(12.79µGy) Pixium 4600-II(9.44µGy)

NNPS RESULTS FOR DIFFERENT DIGITAL RADIOGRAPHY SYSTEMS

1,0E-07 1,0E-06 1,0E-05 1,0E-04

1 2 3 4 NNPS freq(mm-1)

DRX-1C(5.64µGy) DRX-1(5.17µGy) FDX4343R(5.06µGy) Pixium 4600-II(4.6µGy) 1,0E-07 1,0E-06 1,0E-05 1,0E-04

1 2 3 4 eNNPS freq(mm-1)

DRX-1C(4.87µGy) DRX-1(4.39µGy) FDX4343R(5.4µGy) Pixium4600-II(5.09µGy)

RQA G3 G1

1,0E-07 1,0E-06 1,0E-05 1,0E-04

1 2 3 4 NNPS freq(mm-1)

DRX-1C(4.99µGy) DRX-1(4.69µGy) FDX4343R(4.7µGy) Pixium 4600-II(5.12µGy)

DQE-EDQE RESULTS FOR DIFFERENT DIGITAL RADIOGRAPHY SYSTEMS

0,2 0,4 0,6 0,8 1 2 3 4

DQE freq(mm-1)

DRX-1C(5.71µGy) DRX-1(5.17µGy) FDX4343R(5.06µGy) Pixium 4600-II(4.66µGy) 0,0 0,2 0,4

1 2 3 4 eDQE freq(mm-1)

DRX-1C(4.87µGy) DRX-1(4.39µGy) FDX4343R(5.4µGy) Pixium 4600-II(5.09µGy) 0,0 0,2 0,4 0,6 0,8

1 2 3 4 DQE freq(mm-1)

DRX-1C(4.99µGy) DRX-1(4.69µGy) FDX4343R(4.7µGy) Pixium 4600-II(5.12µGy)

RQA G3 G1

COMPARISON OF THREE GEOMETRIES FOR DRX -1C SYSTEM

0,2 0,4 0,6 0,8 1 1 2 3 4 MTF freq (mm-1) G1-90kVp-(4.99µGy) G2_LF-90kVp-(4.99µGy) G2_SF-90kVp-(4.99µGy) G3_90kVp-(4.87µGy) 0,2 0,4 0,6 0,8 1 1 2 3 4 eDQE freq(mm-1) G1_90kVp-(4.99µGy) G2_LF-90kVp-(4.99µGy) G2_SF-90kVp-(4.99µGy) G3_90kVp-(4.87µGy)

Optimization of clinical image quality

CONCLUSION

Could we do some standardization for eDQE ? Could we simplify the eDQE procedure ? Optimization of the clinical techniques Comparison of the clinical performance of different systems Reliable definition of speed for digital system Why to measure the eDQE ?

Thank you

bor@eng.ankara.edu.tr