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www.scint-x.com
Structured scintillators for digital X-Ray imaging
Anna Sahlholm
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Per Wiklund, CEO. M.Sc., DIHM.R&D in VLSI process and device technology. International M&S at Ericsson.
Anna Sahlholm, Process Engineer. M.Sc.
Research experience in materials chemistry.
Olof Svenonius, CTO. M.Sc.Specialist in Optronics and sensors.
Carina Näsgårde, process technicianLong experience from semiconductor process development
Jan Linnros. Professor, KTH Stockholm20 years research in solid state physics. Patent holder. Headed research activities
Advisory Board:
Professors Ulf Welander, Sture Petersson, Christer Fröjd
Scint-X Team
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8/8/2019 M4D Det Structured Scintilla Tors for Digital x Ray Imaging
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Digital vs. Analog x-ray imaging:
+No chemicals involved. Image processing. Easy distribution
+Lower dose
−But lower resolution and contrast
Scint-X solves this problem !
Scintillator technology for imaging x-ray detectors
”state of the art” scintillator Scint-X scintillator
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Scint-X technology
Conventional detector:
Trade-off between resolution andsensitivity
Scintillator (CsI:Tl)
Pixellated sensor (CCD,CMOS)
Scint-X patented solution –
Structured scintillator:
High resolution and high sensitivity
Etched channels (Si wafer)
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66CsI(Tl ) (n=1,79)
SiO 2
(n=1,46)
X-Ray photons(~0-70 keV)
CCD pixel
Silicon
Scintillating waveguide
CCD pixel
θ c =35 °
Light ( λ=550 nm)
Incident X-Rays generate light at 550 nm
wavelength 55 photons/X-ray photon/keV
Critical angle 35° (NA=0,57)
Rays at larger angles absorbed in Si
Advantages:High absorption signal +Light confinement resolution +
Challenge:Waveguide loss signal -
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Modulation Transfer Function (MTF)Ability to reproduce contrast vs. Spatial FrequencySlant edge analysis according to ISO12233- Low frequencies: coarse objects/large fluctuations- High frequencies: fine objects/pixel pitch
Characteristics
Ideal: MTF = sin(x) / x Slant edge applied at small angle
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MTF Comparison:
Characteristics
0 5 10 15 20 250
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
M T F
Frequency [lp/mm]
30 µm
20 µm
40 µm
CsI needle
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Medical X-ray
Intra-oral sensorsThinner detector Improved image resolution and contrastModular scintillator – lower cost
Industrial RadiographyAXI, X-ray microscopy of materials
High resolutionModular scintillator – lower cost
Market for imaging x-ray detectors
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Process
Etched wafers
Deposition of CsI(Tl)
Melting and filling of CsI(Tl), annealing
Polishing
Polymer spinning
Dicing
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X-Ray source:Planmeca Intra, commercial dental sourceE = 60..70 kVpt = 20..800 ms
Sensor:Hamamatsu S8981, commercial oral sensor Scintillator removed – bare FOP1000x1500 pixels, 20x20 µm
20x30 mm active area
Measurement setup
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Results - Comparison with ”state of the art” competing technology
Example: Integrated Circuit X-ray inspection
State of the art scintillator Scint-X scintillator (40 um pitch)
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Results - Comparison with ”state of the art” competing technology
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Research at KTH: publications, PhD thesis, patent
Scint-X AB founded in 2007
Four full time employees
Funding: 10 MSEK (3 MSEK venture capital)
Prototypes tested – anticipated function verified
Two ”Letter of Intent” signed (dental x-ray)
Two orders from Swedish Space Corporation (Material analysis)
Project for industrialization started 2009
Where are we now?
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Thank you!
Questions?
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Results - Comparison with ”state of the art” competing technology
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Conversion Function (CF)Light output vs. Exposure time (dose)- X-Ray to photon conversion- Waveguide efficiency
Sample S14: 365x365 pixels
Characteristics
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VarianceVariance vs. Exposure time (dose)- Total noise: X-Ray induced & other
Sample S14: Gain-compensatedIdeal: Variance = k x Dose
Characteristics
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Signal to Noise Ratio (SNR)Signal (CF) / Noise (√variance) vs. Exposure time (dose)
- Total noise: X-Ray induced & other
Ideal: SNR = k x √Dose
Characteristics