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A low-absorption x-ray energy filter for small-scale applications
KTH, Skolan för teknikvetenskap (SCI), Fysik, Medicinsk bildfysik. KTH, Skolan för bioteknologi (BIO), Centra, Albanova VinnExcellence Center for Protein Technology, ProNova. (Medical Imaging)ORCID-id: 0000-0002-0724-0205
KTH, Skolan för teknikvetenskap (SCI), Fysik, Medicinsk bildfysik. KTH, Skolan för bioteknologi (BIO), Centra, Albanova VinnExcellence Center for Protein Technology, ProNova. (Medical Imaging)
KTH, Skolan för teknikvetenskap (SCI), Fysik, Medicinsk bildfysik. KTH, Skolan för bioteknologi (BIO), Centra, Albanova VinnExcellence Center for Protein Technology, ProNova. (Medical Imaging)ORCID-id: 0000-0002-7725-0548
Uppsala Univ.. (Department of Engineering Sciences)
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2009 (Engelska)Ingår i: Optics Express, E-ISSN 1094-4087, Vol. 17, nr 14, s. 11388-11398Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

We present an experimental and theoretical evaluation of an x-ray energy filter based on the chromatic properties of a prism-array lens (PAL). It is intended for small-scale applications such as medical imaging. The PAL approximates a Fresnel lens and allows for high efficiency compared to filters based on ordinary refractive lenses, however at the cost of a lower energy resolution. Geometrical optics was found to provide a good approximation for the performance of a flawless lens, but a field-propagation model was used for quantitative predictions. The model predicted a 0.29 ΔE/E energy resolution and an intensity gain of 6.5 for a silicon PAL at 23.5 keV. Measurements with an x-ray tube showed good agreement with the model in energy resolution and peak energy, but a blurred focal line contributed to a 29% gain reduction. We believe the blurring to be caused mainly by lens imperfections, in particular at the periphery of the lens.

Ort, förlag, år, upplaga, sidor
The Optical Society , 2009. Vol. 17, nr 14, s. 11388-11398
Nyckelord [en]
X-ray optics, Diffractive lenses, Refractive lenses, Filters, Medical x-ray imaging, Radiation, Wave propagation
Nationell ämneskategori
Atom- och molekylfysik och optik Radiologi och bildbehandling Övrig annan teknik Medicinsk laboratorie- och mätteknik
Identifikatorer
URN: urn:nbn:se:kth:diva-11635DOI: 10.1364/OE.17.011388ISI: 000267761200018PubMedID: 19582053Scopus ID: 2-s2.0-67650544809OAI: oai:DiVA.org:kth-11635DiVA, id: diva2:278567
Anmärkning

QC 20100713

Tillgänglig från: 2009-11-27 Skapad: 2009-11-27 Senast uppdaterad: 2022-09-15Bibliografiskt granskad
Ingår i avhandling
1. Spectral Mammography with X-Ray Optics and a Photon-Counting Detector
Öppna denna publikation i ny flik eller fönster >>Spectral Mammography with X-Ray Optics and a Photon-Counting Detector
2009 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Early detection is vital to successfully treating breast cancer, and mammography screening is the most efficient and wide-spread method to reach this goal. Imaging low-contrast targets, while minimizing the radiation exposure to a large population is, however, a major challenge. Optimizing the image quality per unit radiation dose is therefore essential. In this thesis, two optimization schemes with respect to x-ray photon energy have been investigated: filtering the incident spectrum with refractive x-ray optics (spectral shaping), and utilizing the transmitted spectrum with energy-resolved photon-counting detectors (spectral imaging).

Two types of x-ray lenses were experimentally characterized, and modeled using ray tracing, field propagation, and geometrical optics. Spectral shaping reduced dose approximately 20% compared to an absorption-filtered reference system with the same signal-to-noise ratio, scan time, and spatial resolution. In addition, a focusing pre-object collimator based on the same type of optics reduced divergence of the radiation and improved photon economy by about 50%.

A photon-counting silicon detector was investigated in terms of energy resolution and its feasibility for spectral imaging. Contrast-enhanced tumor imaging with a system based on the detector was characterized and optimized with a model that took anatomical noise into account. Improvement in an ideal-observer detectability index by a factor of 2 to 8 over that obtained by conventional absorption imaging was found for different levels of anatomical noise and breast density. Increased conspicuity was confirmed by experiment. Further, the model was extended to include imaging of unenhanced lesions. Detectability of microcalcifications increased no more than a few percent, whereas the ability to detect large tumors might improve on the order of 50% despite the low attenuation difference between glandular and cancerous tissue. It is clear that inclusion of anatomical noise and imaging task in spectral optimization may yield completely different results than an analysis based solely on quantum noise.

Ort, förlag, år, upplaga, sidor
Stockholm: KTH, 2009. s. x, 56
Serie
Trita-FYS, ISSN 0280-316X ; 2009:69
Nyckelord
mammography; x-ray optics; photon counting; spectral shaping; spectral imaging; collimation; radiation dose; signal-to-noise ratio; quantum noise; anatomical noise; spatial resolution; x-ray flux;
Nationell ämneskategori
Teknik och teknologier Annan teknik Atom- och molekylfysik och optik Övrig annan teknik Elektroteknik och elektronik Medicinsk laboratorie- och mätteknik Radiologi och bildbehandling
Identifikatorer
urn:nbn:se:kth:diva-11641 (URN)978-91-7415-516-7 (ISBN)
Disputation
2009-12-18, Kollegiesalen, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (Engelska)
Opponent
Handledare
Anmärkning
QC 20100714Tillgänglig från: 2009-12-04 Skapad: 2009-11-27 Senast uppdaterad: 2022-06-25Bibliografiskt granskad

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Förlagets fulltextPubMedScopusA low-absorption x-ray energy filter for small-scale applications

Person

Fredenberg, ErikNillius, Peter

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Av författaren/redaktören
Fredenberg, ErikCederström, BjörnNillius, PeterKarlsson, StaffanDanielsson, Mats
Av organisationen
Medicinsk bildfysikAlbanova VinnExcellence Center for Protein Technology, ProNova
I samma tidskrift
Optics Express
Atom- och molekylfysik och optikRadiologi och bildbehandlingÖvrig annan teknikMedicinsk laboratorie- och mätteknik

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