Performance Comparison of Different DR Detectors Using Simplified eDQE Approach Dogan Bor 1 , Ahmet Guven 2 , Turan Olgar 1 , Ozlem Birgul 2 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 W Edge phantom RQA 10x10x1 mm Beam quality Ion Chamber Detector MTF(f) 2 Physical performance of the detector DQE (f) = NNPS (f) . K.q 1,0E-04 1 0,8 0,8 1,0E-05 0,6 NNPS 0,6 MTF DQE 0,4 0,4 1,0E-06 0,2 0,2 0 1,0E-07 0 1 2 3 4 0 1 2 3 4 0 freq (mm -1 ) freq(mm -1 ) 0 1 2 3 4 freq(mm -1 ) *IEC-62220-1
EFFECTIVE DETECTIVE QUANTUM EFFICIENCY- EDQE- Grid 10:1, 40 lp/mm Ion Chamber Detector MTF(f) 2 (1 – SF) 2 Performance of the system as a whole eDQE (f) = NNPS (f) . TF. K.q 1 1,0E-04 0,2 0,8 0,15 1,0E-05 0,6 eNNPS eMTF eDQE 0,1 0,4 1,0E-06 0,05 0,2 0 1,0E-07 0 0 1 2 3 4 0 1 2 3 4 0 1 2 3 4 freq(mm -1 ) freq(mm -1 ) freq(mm -1 ) *Samei et al Med. Phys. 2009
INCLUSION OF SCATTER DATA TO THE MTF Use of Beam Stop Technique PV Atten. SF = PV Backg. 1 0,9 MTF no scatter 0,8 0,7 0,6 MTF 0,5 0,4 0,3 0,2 MTF x (1-SF) 0,1 0 0 0,5 1 1,5 2 2,5 3 3,5 4 freq(mm-1)
INCLUSION OF SCATTER DATA TO THE MTF • 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 LSF for different ROI size 1 0,8 50mm 0,6 40mm 0,4 30mm 20mm 0,2 10mm 0 -30 -20 -10 0 10 20 30 1 -0,2 0,8 10mm(roi) 0,6 20mm(roi) MTF 30mm(roi) 0,4 40mm(roi) 50mm(roi) 0,2 0 0 0,5 1 1,5 2 2,5 3 3,5 freq(mm-1) NHSBSP OBJ_IQ (NW. Marshall)
COMPARISON OF TWO TECHNIQUE 1 1 25cm PMMA 10cm PMMA Increasing 0,8 0,8 ROI size (mm) 10 0,6 20 0,6 MTF MTF . . 0,4 0,4 70 0,2 0,2 0 0 0 1 2 3 0 1 2 3 freq(mm -1 ) freq(mm -1 ) 25cm PMMA 10cm PMMA 0,8 0,8 0,6 0,6 eDQE eDQE 0,4 0,4 SF = 0.38 0,2 0,2 SF = 0.44 0 0 0 1 2 3 0 1 2 3 freq(mm -1 ) freq(mm -1 )
TECHNICAL CHARACTERISTICS OF THE FOUR SYSTEM EVALUATED Philips l Pixium Systems Kodak DRX-1 Kodak DRX-1C Toshiba FDX4343R 4600 Conversion Gd 2 O 2 S:Tb CsI CsI CsI phosphor 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 2.0 1.2 1.2 1.2 size(mm)
ACQUISITION GEOMETRIES IEC Methodology Low scatter, focus unsharpness (G2) Beam hardening filtering (G1) Scatter + focus un harpness (G3) 90 kVp, 25 cm PMMA, AEC control, AK measurements in the Bucky
SIGNAL TRANSFER PROPERTY-STP 1,00E+05 1,0E+05 STP-RQA7(IEC geometri) STP-90kVp_G1 Pixel value (Log axes) 1,00E+04 1,0E+04 Pixel value (Log axes) 1,00E+03 1,0E+03 DRX-1C DRX-1C DRX-1 DRX-1 Toshiba Toshiba Pixium 4600 Pixium 4600 1,00E+02 1,0E+02 0,00 2,00 4,00 6,00 8,00 10,00 0,0 5,0 10,0 15,0 Detector Dose(uGy) Detector Dose(uGy) 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 RQA7 1 0,8 DRX-1C(5.64µGy) DRX-1(5.17µGy) 0,6 FDX4343R(12.79µGy) MTF Pixium 4600-II(9.44µGy) 0,4 0,2 0 0 1 2 3 4 5 freq(mm -1 ) G1 1,0 G3 DRX-1C(4.99µGy) 1,0 DRX-1C(4.87µGy) DRX-1(4.7µGy) DRX-1(4.39µGy) 0,8 0,8 FDX4343R(4.7µGy) FDX4343R(5.4µGy) Pixium4600-II(8.16µGy) Pixium 4600-II(6.44µGy) 0,6 0,6 eMTF MTF 0,4 0,4 0,2 0,2 0,0 0,0 0 1 2 3 4 5 0 1 2 3 4 5 freq(mm -1 ) freq(mm -1 )
NNPS RESULTS FOR DIFFERENT DIGITAL RADIOGRAPHY SYSTEMS RQA 1,0E-04 DRX-1C(5.64µGy) DRX-1(5.17µGy) FDX4343R(5.06µGy) Pixium 4600-II(4.6µGy) 1,0E-05 NNPS 1,0E-06 1,0E-07 0 1 2 3 4 freq(mm -1 ) 1,0E-04 DRX-1C(4.87µGy) G1 G3 1,0E-04 DRX-1C(4.99µGy) DRX-1(4.39µGy) DRX-1(4.69µGy) FDX4343R(5.4µGy) FDX4343R(4.7µGy) Pixium4600-II(5.09µGy) 1,0E-05 Pixium 4600-II(5.12µGy) 1,0E-05 NNPS eNNPS 1,0E-06 1,0E-06 1,0E-07 1,0E-07 0 1 2 3 4 0 1 2 3 4 freq(mm -1 ) freq(mm -1 )
DQE-EDQE RESULTS FOR DIFFERENT DIGITAL RADIOGRAPHY SYSTEMS RQA 0,8 DRX-1C(5.71µGy) DRX-1(5.17µGy) FDX4343R(5.06µGy) 0,6 Pixium 4600-II(4.66µGy) DQE 0,4 0,2 0 0 1 2 3 4 freq(mm -1 ) G1 G3 DRX-1C(4.99µGy) DRX-1C(4.87µGy) 0,8 0,4 DRX-1(4.69µGy) DRX-1(4.39µGy) FDX4343R(4.7µGy) FDX4343R(5.4µGy) Pixium 4600-II(5.09µGy) Pixium 4600-II(5.12µGy) 0,6 DQE eDQE 0,4 0,2 0,2 0,0 0,0 0 1 2 3 4 0 1 2 3 4 freq(mm -1 ) freq(mm -1 )
COMPARISON OF THREE GEOMETRIES FOR DRX -1C SYSTEM 1 G1_90kVp-(4.99µGy) G1-90kVp-(4.99µGy) 1 G2_LF-90kVp-(4.99µGy) G2_LF-90kVp-(4.99µGy) 0,8 0,8 G2_SF-90kVp-(4.99µGy) G2_SF-90kVp-(4.99µGy) G3_90kVp-(4.87µGy) G3_90kVp-(4.87µGy) 0,6 0,6 eDQE MTF 0,4 0,4 0,2 0,2 0 0 0 1 2 3 4 0 1 2 3 4 freq(mm -1 ) freq (mm -1 ) Optimization of clinical image quality
CONCLUSION Could we simplify the eDQE procedure ? Could we do some standardization for eDQE ? Why to measure the eDQE ? Optimization of the clinical techniques Comparison of the clinical performance of different systems Reliable definition of speed for digital system
Thank you bor@eng.ankara.edu.tr
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