Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Characterization of scintillator-based detectors for few-ten-keV high-spatial-resolution x-ray imaging
KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
2016 (English)In: Medical physics (Lancaster), ISSN 0094-2405, Vol. 43, no 6Article in journal (Refereed) Published
Abstract [en]

Purpose: High-spatial-resolution x-ray imaging in the few-ten-keV range is becoming increasingly important in several applications, such as small-animal imaging and phase-contrast imaging. The detector properties critically influence the quality of such imaging. Here the authors present a quantitative comparison of scintillator-based detectors for this energy range and at high spatial frequencies. Methods: The authors determine the modulation transfer function, noise power spectrum (NPS), and detective quantum efficiency for Gadox, needle CsI, and structured CsI scintillators of different thicknesses and at different photon energies. An extended analysis of the NPS allows for direct measurements of the scintillator effective absorption efficiency and effective light yield as well as providing an alternative method to assess the underlying factors behind the detector properties. Results: There is a substantial difference in performance between the scintillators depending on the imaging task but in general, the CsI based scintillators perform better than the Gadox scintillators. At low energies (16 keV), a thin needle CsI scintillator has the best performance at all frequencies. At higher energies (28-38 keV), the thicker needle CsI scintillators and the structured CsI scintillator all have very good performance. The needle CsI scintillators have higher absorption efficiencies but the structured CsI scintillator has higher resolution. Conclusions: The choice of scintillator is greatly dependent on the imaging task. The presented comparison and methodology will assist the imaging scientist in optimizing their high-resolution few-ten-keV imaging system for best performance.

Place, publisher, year, edition, pages
WILEY , 2016. Vol. 43, no 6
Keywords [en]
X-ray detector, scintillator, MTF, NPS, DQE
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
URN: urn:nbn:se:kth:diva-208598DOI: 10.1118/1.4948687ISI: 000401300500006PubMedID: 27277020Scopus ID: 2-s2.0-84969523666OAI: oai:DiVA.org:kth-208598DiVA, id: diva2:1107558
Funder
Swedish Research Council
Note

QC 20170609

Available from: 2017-06-09 Created: 2017-06-09 Last updated: 2018-08-15Bibliographically approved
In thesis
1. Laboratory x-ray fluorescence tomography
Open this publication in new window or tab >>Laboratory x-ray fluorescence tomography
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

X-ray fluorescence (XRF) tomography is an emerging bio-imaging modality with potential for high-resolution molecular imaging in 3D. In this technique the fluorescence signal from targeted nanoparticles (NPs) is measured, providing information about the spatial distribution and concentration of the NPs inside the object. However, present laboratory XRF tomographysystems typically have limited spatial resolution (>1 mm) and suffer from long scan times and high radiation dose even at high NP concentrations, mainly due to low efficiency and poor signal-to-noise ratio (SNR). Other macroscopic biomedical imaging methods provide either structural information with high spatial resolution (e.g., CT) or functional/molecularinformation with lower resolution (e.g., PET).

In this Thesis we present a laboratory XRF tomography system with high spatial resolution (sub-200 μm), low NP concentration and vastly reduced scan times and dose, opening up the possibilities for in vivo small-animal imaging research. The system consists of a high-brightness liquid-metal-jet microfocus x-ray source, x-ray focusing optics and two photon counting detectors. By using the source’s characteristic 24 keV line emission together with spectrally matched molybdenum NPs the Compton background is greatly reduced, increasing the SNR. Each measurement provides information about the spatial distribution and concentration of the NPs, as well as the absorption of the object. An iterative method is used to get aquantitative reconstruction of the XRF image. The reconstructed absorption and XRF images are finally combined into a single 3D overlay image.

Using this system we have demonstrated high-resolution dual CT and XRF imaging of both phantoms and mice at radiation doses compatible with in vivo small-animal imaging.

Abstract [sv]

Röntgenfluorescenstomografi (RFT) är en framväxande avbildningsteknik med potential för högupplöst molekylär avbildning i 3D. Den här tekniken mäter fluorescenssignalen från nanopartiklar vilket ger information om både nanopartiklarnas distribution och koncentration inuti objektet. Nuvarande kompakta system har begränsad upplösning (>1 mm), långa mättider och hög stråldos även vid höga koncentrationer av nanopartiklar, främst på grund av låg effektivitet och dåligt signal-brus-förhållande. Andra makroskopiska avbildningsmetoder ger antingen morfologisk information med hög upplösning (e.g., datortomografi) eller funktionell/molekylär information med lägre upplösning (e.g., positronemissionstomografi).

I denna avhandling presenterar vi ett kompakt RFT-system med hög upplösning (200 μm), låg nanopartikelkoncentration och drastiskt reducerade mättider och dos, vilket öppnar upp möjligheter för in vivo-forskning på smådjur. Systemet består av en metallstrålekälla, röntgenoptik och två fotonräknande detektorer. Genom att använda källans karakteristiska emissionslinje vid 24 keV tillsammans med spektralt matchade molybden-nanopartiklar minskar bakgrunden från Comptonspridning drastiskt, vilket ökar signal-brus-förhållandet. Varje mätning ger både information om nanopartiklarnas distribution och koncentration, samt om objektets absorption. En iterativ metod används för att ge en kvantitativ rekonstruktion av röntgenfluorescensbilden. De rekonstruerade röntgenfluorescens- och absorptionsbilderna kombineras slutligen till en enda 3D-bild.

Med det här systemet har vi demonstrerat högupplöst avbildning av både fantomer och möss vid stråldoser som är kompatibla med in vivo-avbildning av smådjur.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2018. p. xi, 67
Series
TRITA-SCI-FOU ; 2018:16
Keywords
x-ray, fluorescence, x-ray fluorescence, nanoparticle, xrf, xfct, tomography
National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:kth:diva-233149 (URN)978-91-7729-796-3 (ISBN)
Public defence
2018-09-07, FR4, Albanova Universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

QC 20180816

Available from: 2018-08-16 Created: 2018-08-15 Last updated: 2018-08-16Bibliographically approved

Open Access in DiVA

No full text in DiVA

Other links

Publisher's full textPubMedScopus

Search in DiVA

By author/editor
Larsson, Jakob C.Lundström, UlfHertz, Hans M.
By organisation
Biomedical and X-ray Physics
In the same journal
Medical physics (Lancaster)
Radiology, Nuclear Medicine and Medical Imaging

Search outside of DiVA

GoogleGoogle Scholar

doi
pubmed
urn-nbn

Altmetric score

doi
pubmed
urn-nbn
Total: 20 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf