Large scale xray images taken with the Medipix

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Large scale x-ray images taken with the Medipix 1 chip Karl-Friedrich Pfeiffer Physikalisches Institut,

Large scale x-ray images taken with the Medipix 1 chip Karl-Friedrich Pfeiffer Physikalisches Institut, Abt. 4 Universität Erlangen-Nürnberg Workgroup SPOC* K. -F. Pfeiffer, PI 4 Universität Erlangen-Nürnberg Medipix Collaboration *Single Ph. Oton Counting 1 IWORID 4, September 2002

Overview " The Medipix 1 chip " Experimental setup " " Large Images 1:

Overview " The Medipix 1 chip " Experimental setup " " Large Images 1: 'Move and Tile' Measurement and Simulation Large Images 2: 'Tile and Move' Measurement and Simulation " DQE Measurements " Summary K. -F. Pfeiffer, PI 4 Universität Erlangen-Nürnberg 2 IWORID 4, September 2002

The Medipix 1 chip " Pixelated solid state hybrid detector for single photon counting

The Medipix 1 chip " Pixelated solid state hybrid detector for single photon counting " 64 x 64 Pixel, size 170 mm Þ active area 10. 88 x 10. 88 mm 2 " " " Semiconductor sensor layer bump-bonded to the pixelated read-out electronics chip Sensor layer: e. g. 300 mm Si, but other materials (Ga. As, Cd(Z)Te. . . ) can be used as well Developed within the framework of the Medipix 1 collaboration K. -F. Pfeiffer, PI 4 Universität Erlangen-Nürnberg 3 IWORID 4, September 2002

Experimental setup Computer 1: main control Computer 2: data acquisition X-ray generator MUROS 1

Experimental setup Computer 1: main control Computer 2: data acquisition X-ray generator MUROS 1 board & Medipix 1 chip Translation stages " " " Complete imaging process controlled by computer 1 Data acquisition done with Medisoftware (developed in the Medipix collaboration) (Semi-)automated processing of acquired data K. -F. Pfeiffer, PI 4 Universität Erlangen-Nürnberg 4 IWORID 4, September 2002

Large Images 1: 'Move and Tile' " Make single exposure with single detector "

Large Images 1: 'Move and Tile' " Make single exposure with single detector " Move detector to next position " Make another exposure " " Repeat until the whole area is covered Merge all single exposures to get one large tiled image K. -F. Pfeiffer, PI 4 Universität Erlangen-Nürnberg 5 IWORID 4, September 2002

Large Images 1: Measurement 5 x 5 single exposures, 10 pixels overlap K. -F.

Large Images 1: Measurement 5 x 5 single exposures, 10 pixels overlap K. -F. Pfeiffer, PI 4 Universität Erlangen-Nürnberg 6 IWORID 4, September 2002

Comparison Measurement - Simulation Object: „Siemensstern“ 0. 05 mm Pb in 2 mm PMMA

Comparison Measurement - Simulation Object: „Siemensstern“ 0. 05 mm Pb in 2 mm PMMA Ø 4. 5 cm " " Contrast Pb -Air: 0. 965 Contrast Pb-PMMA: 0. 941 K. -F. Pfeiffer, PI 4 Universität Erlangen-Nürnberg Contrast ratio measurement -simulation: 0. 996 " " 0. 978 7 Contrast Pb -Air: 0. 969 Contrast Pb-PMMA: 0. 962 IWORID 4, September 2002

Large Images 2: 'Tile and Move' " Tile several detectors to make an array

Large Images 2: 'Tile and Move' " Tile several detectors to make an array " Take large picture (with gaps) " Move array to next position " Take another picture " Repeat to cover all gaps " Merge pictures to get one large image without gaps and with high photon statistics K. -F. Pfeiffer, PI 4 Universität Erlangen-Nürnberg 8 IWORID 4, September 2002

Large Images 2: Measurement 3 images, 4 x 4 tiles each K. -F. Pfeiffer,

Large Images 2: Measurement 3 images, 4 x 4 tiles each K. -F. Pfeiffer, PI 4 Universität Erlangen-Nürnberg 9 IWORID 4, September 2002

Comparison Measurement - Simulation Object: „Siemensstern“ 0. 05 mm Pb in 2 mm PMMA

Comparison Measurement - Simulation Object: „Siemensstern“ 0. 05 mm Pb in 2 mm PMMA Ø 4. 5 cm " " Contrast Pb -Air: 0. 954 Contrast Pb-PMMA: 0. 928 K. -F. Pfeiffer, PI 4 Universität Erlangen-Nürnberg Contrast ratio measurement -simulation: 0. 988 " " 0. 964 10 Contrast Pb -Air: 0. 966 Contrast Pb-PMMA: 0. 963 IWORID 4, September 2002

Improved 'Tile and Move' If it is possible to tile several detecors without gaps

Improved 'Tile and Move' If it is possible to tile several detecors without gaps (e. g. with the Medipix 2 chip): Þ Tile detectors to get ’detector bars': two pictures are sufficient to cover all gaps Þ even faster & less dose! K. -F. Pfeiffer, PI 4 Universität Erlangen-Nürnberg 11 IWORID 4, September 2002

DQE Definition " DQE: Detective Quantum Efficiency " SNR: Signal-to-Noise-Ratio " 1 in: SNR

DQE Definition " DQE: Detective Quantum Efficiency " SNR: Signal-to-Noise-Ratio " 1 in: SNR of incoming radiation field (~ N ) 2 out: SNR of the image f = f(x, y): Spatial frequency K. -F. Pfeiffer, PI 4 Universität Erlangen-Nürnberg 12 IWORID 4, September 2002

Calculation of the DQE MTF NPS <E> 0 K. -F. Pfeiffer, PI 4 Universität

Calculation of the DQE MTF NPS <E> 0 K. -F. Pfeiffer, PI 4 Universität Erlangen-Nürnberg : System gain factor : Modulation Transfer Function : Noise Power Spectrum : Mean photon energy : Incoming energy fluence 13 IWORID 4, September 2002

DQE Measurement " " " MTF(f) measurement: line pair phantom NPSout measurement: flat field

DQE Measurement " " " MTF(f) measurement: line pair phantom NPSout measurement: flat field images. . . some lenghty calculations. . . Þ DQE(f) 15. 5 cm K. -F. Pfeiffer, PI 4 Universität Erlangen-Nürnberg 14 IWORID 4, September 2002

MTF: results K. -F. Pfeiffer, PI 4 Universität Erlangen-Nürnberg 15 IWORID 4, September 2002

MTF: results K. -F. Pfeiffer, PI 4 Universität Erlangen-Nürnberg 15 IWORID 4, September 2002

First DQE results K. -F. Pfeiffer, PI 4 Universität Erlangen-Nürnberg 16 IWORID 4, September

First DQE results K. -F. Pfeiffer, PI 4 Universität Erlangen-Nürnberg 16 IWORID 4, September 2002

Summary " There are basically two ways to get large field images: 1) 'Move

Summary " There are basically two ways to get large field images: 1) 'Move and Tile': single detector, flexible, but takes quite a long time and high dose Þ 'Lab Method' 2) 'Tile and Move': quite fast, but requires several detectors Þ 'Standard Imaging Method' " " The MTF and DQE of a Medipix 1 chip with a 300 mm Si sensor layer was determined We are looking forward to the Medipix 2 chip K. -F. Pfeiffer, PI 4 Universität Erlangen-Nürnberg 17 IWORID 4, September 2002

Thanks to: " Prof. G. Anton 1 " Ch. Bert 1 & D. Niederlöhner

Thanks to: " Prof. G. Anton 1 " Ch. Bert 1 & D. Niederlöhner 1 " J. Giersch 1 " M. Hoheisel 2 & L. Bätz 2 (for the DQE calculations) " Medipix Collaboration " B. Mikulec 3 1 Universität Erlangen K. -F. Pfeiffer, PI 4 Universität Erlangen-Nürnberg 2 Siemens 3 CERN 18 IWORID 4, September 2002

Phantoms used: Siemensstern K. -F. Pfeiffer, PI 4 Universität Erlangen-Nürnberg Line pair phantom 19

Phantoms used: Siemensstern K. -F. Pfeiffer, PI 4 Universität Erlangen-Nürnberg Line pair phantom 19 IWORID 4, September 2002

Background picture: blown fuse K. -F. Pfeiffer, PI 4 Universität Erlangen-Nürnberg 20 IWORID 4,

Background picture: blown fuse K. -F. Pfeiffer, PI 4 Universität Erlangen-Nürnberg 20 IWORID 4, September 2002

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