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Bornefalk, Hans
Publications (6 of 6) Show all publications
Persson, M., Holmin, S., Karlsson, S., Bornefalk, H. & Danielsson, M. (2018). Subpixel x-ray imaging with an energy-resolving detector. Journal of Medical Imaging, 5(1), Article ID 013507.
Open this publication in new window or tab >>Subpixel x-ray imaging with an energy-resolving detector
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2018 (English)In: Journal of Medical Imaging, ISSN 2329-4302, E-ISSN 2329-4310, Vol. 5, no 1, article id 013507Article in journal (Refereed) Published
Abstract [en]

The detector pixel size can be a severe limitation in x-ray imaging of fine details in the human body. We demonstrate a method of using spectral x-ray measurements to image the spatial distribution of the linear attenuation coefficient on a length scale smaller than one pixel, based on the fact that interfaces parallel to the x-ray beam have a unique spectral response, which distinguishes them from homogeneous materials. We evaluate the method in a simulation study by simulating projection imaging of the border of an iodine insert with 200 mg/ml I in a soft tissue phantom. The results show that the projected iodine profile can be recovered with an RMS resolution of 5% to 34% of the pixel size, using an ideal energy-resolving detector. We also validate this method in an experimental study by imaging an iodine insert in a polyethylene phantom using a photon-counting silicon-strip detector. The results show that abrupt and gradual transitions can be distinguished based on the transmitted x-ray spectrum, in good agreement with simulations. The demonstrated method may potentially be used for improving visualization of blood vessel boundaries, e.g., in acute stroke care.

Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2018
Keywords
x-ray imaging, subpixel information, spectral x-ray imaging, photon-counting detector, partial volume effect
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:kth:diva-226818 (URN)10.1117/1.JMI.5.1.013507 (DOI)000429258000030 ()29564367 (PubMedID)2-s2.0-85044647808 (Scopus ID)
Funder
VINNOVA, 2014-03800Stockholm County Council, 20140712
Note

QC 20180503

Available from: 2018-05-03 Created: 2018-05-03 Last updated: 2018-05-03Bibliographically approved
Liu, X., Persson, M., Bornefalk, H., Karlsson, S., Xu, C., Danielsson, M. & Huber, B. (2016). Spectral response model for a multibin photon-counting spectral computed tomography detector and its applications (vol 2, 033502, 2015). Journal of Medical Imaging, 3(4), Article ID 049801.
Open this publication in new window or tab >>Spectral response model for a multibin photon-counting spectral computed tomography detector and its applications (vol 2, 033502, 2015)
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2016 (English)In: Journal of Medical Imaging, ISSN 2329-4302, E-ISSN 2329-4310, Vol. 3, no 4, article id 049801Article in journal (Refereed) Published
Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2016
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:kth:diva-200772 (URN)10.1117/1.JMI.3.4.049801 (DOI)000391124500025 ()
Note

20170206

Available from: 2017-02-06 Created: 2017-02-02 Last updated: 2017-06-22Bibliographically approved
Persson, M., Bujila, R., Nowik, P., Andersson, H., Kull, L., Andersson, J., . . . Danielsson, M. (2016). Upper limits of the photon fluence rate on CT detectors: Case study on a commercial scanner. Medical physics (Lancaster), 43(7), 4398-4411
Open this publication in new window or tab >>Upper limits of the photon fluence rate on CT detectors: Case study on a commercial scanner
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2016 (English)In: Medical physics (Lancaster), ISSN 0094-2405, Vol. 43, no 7, p. 4398-4411Article in journal (Refereed) Published
Abstract [en]

Purpose: The highest photon fluence rate that a computed tomography (CT) detector must be able to measure is an important parameter. The authors calculate the maximum transmitted fluence rate in a commercial CT scanner as a function of patient size for standard head, chest, and abdomen protocols. Methods: The authors scanned an anthropomorphic phantom (Kyoto Kagaku PBU-60) with the reference CT protocols provided by AAPM on a GE LightSpeed VCT scanner and noted the tube current applied with the tube current modulation (TCM) system. By rescaling this tube current using published measurements on the tube current modulation of a GE scanner [N. Keat, "CT scanner automatic exposure control systems," MHRA Evaluation Report 05016, ImPACT, London, UK, 2005], the authors could estimate the tube current that these protocols would have resulted in for other patient sizes. An ECG gated chest protocol was also simulated. Using measured dose rate profiles along the bowtie filters, the authors simulated imaging of anonymized patient images with a range of sizes on a GE VCT scanner and calculated the maximum transmitted fluence rate. In addition, the 99th and the 95th percentiles of the transmitted fluence rate distribution behind the patient are calculated and the effect of omitting projection lines passing just below the skin line is investigated. Results: The highest transmitted fluence rates on the detector for the AAPM reference protocols with centered patients are found for head images and for intermediate-sized chest images, both with a maximum of 3.4 . 10(8) mm(-2) s-1, at 949 mm distance from the source. Miscentering the head by 50 mm downward increases the maximum transmitted fluence rate to 5.7 . 10(8) mm(-2) s(-1). The ECG gated chest protocol gives fluence rates up to 2.3 . 10(8)-3.6 . 10(8) mm(-2) s(-1) depending on miscentering. Conclusions: The fluence rate on a CT detector reaches 3 . 10(8)-6 . 10(8) mm(-2) s(-1) in standard imaging protocols, with the highest rates occurring for ECG gated chest and miscentered head scans. These results will be useful to developers of CT detectors, in particular photon counting detectors. (C) 2016 American Association of Physicists in Medicine.

Place, publisher, year, edition, pages
AMER ASSOC PHYSICISTS MEDICINE AMER INST PHYSICS, 2016
Keywords
fluence rate, count rate requirements, count rate problem, photon counting CT
National Category
Medical Equipment Engineering
Identifiers
urn:nbn:se:kth:diva-243843 (URN)10.1118/1.4954008 (DOI)000379171900044 ()27370155 (PubMedID)2-s2.0-84976381566 (Scopus ID)
Note

QC 20190207

Available from: 2019-02-07 Created: 2019-02-07 Last updated: 2019-02-07Bibliographically approved
Grönberg, F., Persson, M. & Bornefalk, H. (2015). Image reconstruction based on energy-resolved image data from a photon-counting multi-bin detector. us 9870628B2.
Open this publication in new window or tab >>Image reconstruction based on energy-resolved image data from a photon-counting multi-bin detector
2015 (English)Patent (Other (popular science, discussion, etc.))
Abstract [en]

There is provided a method of image reconstruction based on energy-resolved image data from a photon-counting multi-bin detector or an intermediate storage. The method comprises processing (S1) the energy-resolved image data by performing at least two separate basis decompositions using different number of basis functions for modeling linear attenuation, wherein a first basis decomposition is performed using a first smaller set of basis functions to obtain at least one first basis image representation, and wherein a second basis decomposition is performed using a second larger set of basis functions to obtain at least one second basis image representation. The method also comprises reconstructing a first image based on said at least one first basis image representation obtained from the first basis decomposition, and combining the first image with information representative of said at least one second basis image representation.

National Category
Medical Image Processing
Identifiers
urn:nbn:se:kth:diva-260501 (URN)
Patent
US 9870628B2 (2018-01-16)
Note

QC 20191014

Available from: 2019-09-30 Created: 2019-09-30 Last updated: 2019-10-14Bibliographically approved
Grönberg, F., Persson, M. & Bornefalk, H. (2015). Third material separation in spectral CT with basis decomposition. In: : . Paper presented at Proceedings of The 13th International Meeting on Fully Three-Dimensional Image Reconstruction in Radiology and Nuclear Medicine.
Open this publication in new window or tab >>Third material separation in spectral CT with basis decomposition
2015 (English)Conference paper, Published paper (Other academic)
National Category
Medical Image Processing
Identifiers
urn:nbn:se:kth:diva-250641 (URN)
Conference
Proceedings of The 13th International Meeting on Fully Three-Dimensional Image Reconstruction in Radiology and Nuclear Medicine
Note

QC 20190625

Available from: 2019-05-01 Created: 2019-05-01 Last updated: 2019-06-25Bibliographically approved
Yao, Y., Bornefalk, H., Hsieh, S. S., Danielsson, M. & Pelc, N. J. (2014). UTILIZATION OF IN-DEPTH PHOTON COUNTING DETECTORS TOWARDS X-RAY SPECTRAL IMAGING: THE BENEFITS FROM THE DEPTH INFORMATION. In: 2014 IEEE 11th International Symposium on Biomedical Imaging (ISBI): . Paper presented at 11th IEEE International Symposium on Biomedical Imaging (ISBI), APR 29-MAY 02, 2014, Beijing, PEOPLES R CHINA (pp. 1156-1159). IEEE
Open this publication in new window or tab >>UTILIZATION OF IN-DEPTH PHOTON COUNTING DETECTORS TOWARDS X-RAY SPECTRAL IMAGING: THE BENEFITS FROM THE DEPTH INFORMATION
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2014 (English)In: 2014 IEEE 11th International Symposium on Biomedical Imaging (ISBI), IEEE , 2014, p. 1156-1159Conference paper, Published paper (Refereed)
Abstract [en]

The in-depth photon counting x-ray detector (PCXD) is a multi-layer detector arrangement which has been introduced to tackle photon count rate limitations of current systems. The capability of resolving photon detections along the detector's depth direction enables multiple measurements in a single scan with energy information that could be potentially utilized for x-ray spectral imaging. The benefit of this depth information has not been explored. We conducted a simulation study to evaluate the performance of in-depth PCXDs for dual material decomposition and compared it against single layer detectors. Common semiconductor materials (Si, GaAs and CdTe) were assessed, with imperfect energy response modeled. We demonstrate that depth information is useful if spectral distortion is present. The benefits depend on how the detector is segmented in the depth direction.

Place, publisher, year, edition, pages
IEEE, 2014
Series
IEEE International Symposium on Biomedical Imaging, ISSN 1945-7928
Keywords
photon counting, depth information, Cramer-Rao lower bound, energy response, material decomposition
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:kth:diva-243776 (URN)000392750900287 ()978-1-4673-1961-4 (ISBN)
Conference
11th IEEE International Symposium on Biomedical Imaging (ISBI), APR 29-MAY 02, 2014, Beijing, PEOPLES R CHINA
Note

QC 20190211

Available from: 2019-02-11 Created: 2019-02-11 Last updated: 2019-02-11Bibliographically approved
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