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Sökning: WFRF:(Holstensson Maria)

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1.
  • Fan, Peng, et al. (författare)
  • Scatter and crosstalk corrections for (99m)Tc/(123)I dual-radionuclide imaging using a CZT SPECT system with pinhole collimators.
  • 2015
  • Ingår i: Medical Physics. - : American Association of Physicists in Medicine. - 0094-2405 .- 2473-4209. ; 42:12, s. 6895-6911
  • Tidskriftsartikel (refereegranskat)abstract
    • The energy spectrum for a cadmium zinc telluride (CZT) detector has a low energy tail due to incomplete charge collection and intercrystal scattering. Due to these solid-state detector effects, scatter would be overestimated if the conventional triple-energy window (TEW) method is used for scatter and crosstalk corrections in CZT-based imaging systems. The objective of this work is to develop a scatter and crosstalk correction method for (99m)Tc/(123)I dual-radionuclide imaging for a CZT-based dedicated cardiac SPECT system with pinhole collimators (GE Discovery NM 530c/570c).
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2.
  • Holstensson, Maria, et al. (författare)
  • Comparison of acquisition protocols for ventilation/perfusion SPECT - a Monte Carlo study
  • 2019
  • Ingår i: Physics in Medicine and Biology. - : Institute of Physics (IOP). - 0031-9155 .- 1361-6560. ; 64:23
  • Tidskriftsartikel (refereegranskat)abstract
    • One of the most commonly used imaging techniques for diagnosing pulmonary embolism (PE) is ventilation/perfusion (V/P) scintigraphy. The aim of this study was to evaluate the performance of the currently used imaging protocols for V/P single photon emission computed tomography (V/P SPECT) at two nuclear medicine department sites and to investigate the effect of altering important protocol parameters. 
 
 The Monte Carlo technique was used to simulate 4D digital phantoms with perfusion defects. Six imaging protocols were included in the study and a total of 72 digital patients were simulated. Six dually trained radiologists/nuclear medicine physicians reviewed the images and reported all perfusion mismatch findings. The radiologists also visually graded the image quality. 
 
 No statistically significant differences in diagnostic performance were found between the studied protocols, but visual grading analysis pointed out one protocol as significantly superior to four of the other protocols. Considering the study results, we have decided to harmonize our clinical protocols for imaging patients with suspected PE. The administered Technegas and macro aggregated albumin activities have been altered, a low energy all purpose collimator is used instead of a low energy high resolution collimator and the acquisition times have been lowered.
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3.
  • Holstensson, Maria, et al. (författare)
  • Optimization of energy-window settings for scatter correction in quantitative In-111 imaging: Comparison of measurements and Monte Carlo simulations
  • 2007
  • Ingår i: Cancer Biotherapy & Radiopharmaceuticals. - : Mary Ann Liebert, Inc.. - 1557-8852. ; 22:1, s. 136-142
  • Tidskriftsartikel (refereegranskat)abstract
    • Activity quantification in nuclear medicine imaging is highly desirable, particularly for dosimetry and biodistribution studies of radiopharmaceuticals. Quantitative In-111 imaging is increasingly important with the current interest in therapy using Y-90 radiolabeled antibodies. One of the major problems in quantification is scatter in the images, which leads to degradation of image quality. The aim of this study was to optimize the energy-window settings for quantitative In-111 imaging with a camera that enabled acquisition in three energy windows. Experimental measurements and Monte Carlo simulations, using the SI-MIND code, were conducted to investigate parameters such as sensitivity, image contrast, and image resolution. Estimated scatter-to-total ratios and distributions, as obtained by the different window settings, were compared with corresponding simulations. Results showed positive agreement between experimental measurements and results from simulations, both quantitatively and qualitatively. We conclude that of the investigated methods, the optimal energy-window setting was two windows centered at 171 and 245 keV, together with a broad scatter window located between the photopeaks.
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4.
  • Sigfridsson, Jonathan, et al. (författare)
  • Prospective data-driven respiratory gating of [Ga-68]Ga-DOTATOC PET/CT
  • 2021
  • Ingår i: EJNMMI Research. - : SPRINGER. - 2191-219X .- 2191-219X. ; 11
  • Tidskriftsartikel (refereegranskat)abstract
    • Aim: The aim of this prospective study was to evaluate a data-driven gating software's performance, in terms of identifying the respiratory signal, comparing [Ga-68]Ga-DOTATOC and [F-18]FDG examinations. In addition, for the [Ga-68]Ga-DOTATOC examinations, tracer uptake quantitation and liver lesion detectability were assessed.Methods: Twenty-four patients with confirmed or suspected neuroendocrine tumours underwent whole-body [Ga-68]Ga-DOTATOC PET/CT examinations. Prospective DDG was applied on all bed positions and respiratory motion correction was triggered automatically when the detected respiratory signal exceeded a certain threshold (R value >= 15), at which point the scan time for that bed position was doubled. These bed positions were reconstructed with quiescent period gating (QPG), retaining 50% of the total coincidences. A respiratory signal evaluation regarding the software's efficacy in detecting respiratory motion for [Ga-68]Ga-DOTATOC was conducted and compared to [F-18]FDG data. Measurements of SUVmax, SUVmean, and tumour volume were performed on [Ga-68]Ga-DOTATOC PET and compared between gated and non-gated images.Results: The threshold of R >= 15 was exceeded and gating triggered on mean 2.1 bed positions per examination for [Ga-68]Ga-DOTATOC as compared to 1.4 for [F-18]FDG. In total, 34 tumours were evaluated in a quantitative analysis. An increase of 25.3% and 28.1%, respectively, for SUVmax (P < 0.0001) and SUVmean (P < 0.0001), and decrease of 21.1% in tumour volume (P < 0.0001) was found when DDG was applied.Conclusions: High respiratory signal was exclusively detected in bed positions where respiratory motion was expected, indicating reliable performance of the DDG software on [Ga-68]Ga-DOTATOC PET/CT. DDG yielded significantly higher SUVmax and SUVmean values and smaller tumour volumes, as compared to non-gated images.
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