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  • 1.
    Davidsson, Anette
    et al.
    Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    Georgiopoulos, C
    Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    Gustafsson, Agnetha
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Zachrisson, Helene
    Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    Evaluation and comparison of quantification tools for early diagnosis of Parkinson's disease with DaTSCAN SPECT.2011Konferansepaper (Fagfellevurdert)
  • 2.
    Davidsson, Anette
    et al.
    Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    Georgiopoulos, C
    Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    Gustafsson, Agnetha
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Zachrisson, Helene
    Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    Utvärdering och jämförelse av kvantifieringsverktyg för tidig diagnostik av Parkinsons sjukdom med DaTSCAN SPECT2011Konferansepaper (Annet vitenskapelig)
  • 3.
    Davidsson, Anette
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Klinisk fysiologi. Linköpings universitet, Hälsouniversitetet.
    Olsson, Eva
    Linköpings universitet, Institutionen för medicin och hälsa, Klinisk fysiologi. Linköpings universitet, Hälsouniversitetet.
    Engvall, Jan
    Linköpings universitet, Institutionen för medicin och hälsa, Klinisk fysiologi. Linköpings universitet, Hälsouniversitetet.
    Gustafsson, Agnetha
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Assessment of image quality for SPECT myocardial perfusion imaging with regard to reconstruction algorithms using visual grading regression.2012Konferansepaper (Annet vitenskapelig)
  • 4.
    Davidsson, Anette
    et al.
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och hälsa, Klinisk fysiologi.
    Olsson, Eva
    Linköpings universitet, Institutionen för medicin och hälsa, Klinisk fysiologi.
    Engvall, Jan
    Linköpings universitet, Institutionen för medicin och hälsa, Klinisk fysiologi.
    Gustafsson, Agnetha
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Visuell bedömning av bildkvalitet vid Myokardscintigrafi med avseende på rekonstruktionsalgoritmer2012Konferansepaper (Annet vitenskapelig)
  • 5.
    Gustafsson, Agneta
    et al.
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och hälsa. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Granerus, Göran
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och hälsa, Klinisk fysiologi. Östergötlands Läns Landsting, Hjärtcentrum, Fysiologiska kliniken.
    Zachrisson, Helene
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och hälsa, Klinisk fysiologi. Östergötlands Läns Landsting, Hjärtcentrum, Fysiologiska kliniken.
    Evaluation of the OSEM reconstruction techniques used in DATscan.2008Inngår i: Nuklearmedicinska vårmötet,2008, 2008Konferansepaper (Fagfellevurdert)
  • 6.
    Gustafsson, Agneta
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Karlsson, Henrik
    Kalmar County Hospital, Sweden.
    Nilsson, Kerstin A.
    Geijer, Hakan
    Örebro University Hospital, Sweden.
    Olsson, Anna
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Medicinska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    A visual grading study for different administered activity levels in bone scintigraphy2015Inngår i: Clinical Physiology and Functional Imaging, ISSN 1475-0961, E-ISSN 1475-097X, Vol. 35, nr 3, s. 231-236Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    IntroductionThe aim of the study is to assess the administered activity levels versus visual-based image quality using visual grading regression (VGR) including an assessment of the newly stated image criteria for whole-body bone scintigraphy. Materials and methodsA total of 90 patients was included and grouped in three levels of administered activity: 400, 500 and 600 MBq. Six clinical image criteria regarding image quality was formulated by experienced nuclear medicine physicians. Visual grading was performed in all images, where three physicians rated the fulfilment of the image criteria on a four-step ordinal scale. The results were analysed using VGR. A count analysis was also made where the total number of counts in both views was registered. ResultsThe administered activity of 600 MBq gives significantly better image quality than 400 MBq in five of six criteria (Pless than005). Comparing the administered activity of 600 MBq to 500 MBq, four criteria of six show significantly better image quality (Pless than005). The administered activity of 500 MBq gives no significantly better image quality than 400 Mbq (Pless than005). The count analysis shows that none of the three levels of administrated activity fulfil the recommendations by the EANM. ConclusionThere was a significant improvement in perceived image quality using an activity level of 600 MBq compared to lower activity levels in whole-body bone scintigraphy for the gamma camera equipment end set-up used in this study. This type of visual-based grading study seems to be a valuable tool and easy to implement in the clinical environment.

  • 7.
    Gustafsson, Agnetha
    Department of Radiations Physics, Avdelningen för radiofysik, Göteborgs universitet.
    Evaluation of attenuation and scatter corrections in lung and brain SPECT2001Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Single Photon Emission Computed Tomography (SPECT) is used to image functional processes in the human body. The image process is affected by physical effects such as attenuation, scatter, spatial resolution and statistical noise. The aim of this work was to investigate how attenuation and scatter effects and their associated correction methods affect the image quality in lung and brain SPECT.

    The effects of attenuation and scattering on the image of a uniform activity distribution in the lungs was investigated using Monte Carlo simulated data and the attenuation effect was evaluated in healthy volunteers. The homogeneity was measured as the CV inside a well-defined lung contour. The attenuation effect in lung SPECT was estimated to be about 13-14% expressed as the CV. The homogeneity improved with increasing accuracy of the attenuation correction method. After attenuation correction the remaining inhomogeneity in healthy subjects was considerable and could not be explained by statistical noise and camera non-uniformity. A non-uniform attenuation correction was thus required and a TCT-based density map was found to be adequate in most instances.

    The accuracy of the attenuation correction methods was studied in Monte Carlo simulated brain SPECT using the normalised mean square error, NMSE. The different degrees of accuracy in the methods were also reflected in the absolute deviation of the relative regional cerebral blood flow (rCBF) according to the min-max method. The NMSE value improved with the accuracy of the attenuationcorrection method. The difference in relative rCBF value was generally less than 5%. Therefore, it is unlikely that the choice of attenuation correction method will affect the diagnostic accuracy.

    The detectability, expressed as the contrast-to-noise-ratio dependence on the choice of energy window, was evaluated using SPECT studies of a thorax phantom containing cold lesions inside the lungs and a realistic brain phantom. The effects of subtractive scatter correction methods such as the dual-window method (DW), the triple-energy-window method (TEW) and the Klein-Nishina method (KN) were also evaluated. An optimal photopeak window setting was found to be 128-154 keV in lung SPECT for a gamma camera with 10% energy resolution, and 130-154 keV in rCBF SPECT for a gamma camera with 9% energy resolution. The detection limit for lung SPECT for spherical lesions is about 2 cm in diameter when normal variations in the lungs are relatively small compared with the statistical noise level. Under these conditions the detectability is degraded by using scatter correction, except when the TEW scatter correction is used for small lesions (<3 cm in diameter), when about the same detectability is achieved.

    Delarbeid
    1. Evaluation of attenuation corrections using Monte Carlo simulated lung SPECT
    Åpne denne publikasjonen i ny fane eller vindu >>Evaluation of attenuation corrections using Monte Carlo simulated lung SPECT
    Vise andre…
    1998 (engelsk)Inngår i: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 43, nr 8, s. 2325-2336Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    SPECT (single photon emission computed tomography) images are distorted by photon attenuation. The effect is complex in the thoracic region due to different tissue densities. This study compares the effect on the image homogeneity of two different methods of attenuation correction in lung SPECT; one pre-processing and one post-processing method. This study also investigates the impact of attenuation correction parameters such as lung contour, body contour, density of the lung tissue and effective attenuation coefficient. The Monte Carlo technique was used to simulate SPECT studies of a digital thorax phantom containing a homogeneous activity distribution in the lung. Homogeneity in reconstructed images was calculated as the coefficient of variation (CV). The isolated effect of the attenuation correction was assessed by normalizing pixel values from the attenuation corrected lung by pixel values from the lung with no attenuation effects. Results show that the CV decreased from 12.8% with no attenuation correction to 4.4% using the post-processing method and true densities in the thoracic region. The impact of variations in the definition of the body contour was found to be marginal while the corresponding effect of variations in the lung contour was substantial.

    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-79205 (URN)10.1088/0031-9155/43/8/023 (DOI)9725607 (PubMedID)
    Tilgjengelig fra: 2012-07-03 Laget: 2012-07-03 Sist oppdatert: 2018-09-17
    2. Evaluation of various attenuation corrections in lung SPECT in healthy subjects
    Åpne denne publikasjonen i ny fane eller vindu >>Evaluation of various attenuation corrections in lung SPECT in healthy subjects
    Vise andre…
    2003 (engelsk)Inngår i: Nuclear medicine communications, ISSN 0143-3636, E-ISSN 1473-5628, Vol. 24, nr 10, s. 1087-1095Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    The effect of increasingly more sophisticated attenuation correction methods on image homogeneity has been studied in seven healthy subjects. The subjects underwent computed tomography (CT), single photon emission computed tomography (SPECT) and transmission computed tomography (TCT) of the thorax region in the supine position. Density maps were obtained from the CT and TCT studies. Attenuation corrections were performed using five different methods: (1) uniform correction using only the body contour, (2) TCT based corrections using the average lung density, (3) TCT based corrections using the pixel density, (4) CT based corrections using average lung density, and (5) CT based corrections using the pixel density. The isolated attenuation effects were assessed on quotient images generated by the division of images obtained using various attenuation correction methods divided by the non-uniform attenuation correction based on CT pixel density (reference method). The homogeneity was calculated as the coefficient of variation of the quotient images (CVatt), showing the isolated attenuation effects. Values of CVatt were on average 12.8% without attenuation correction, 10.7% with the uniform correction, 8.1% using TCT map using the average lung density value and 4.8% using CT and average lung density corrections. There are considerable inhomogeneities in lung SPECT slices due to the attenuation effect. After attenuation correction the remaining inhomogeneity is considerable and cannot be explained by statistical noise and camera non-uniformity alone.

    Emneord
    attenuation correction, SPECT, lung and thorax region
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-47749 (URN)10.1097/00006231-200310000-00009 (DOI)
    Tilgjengelig fra: 2009-10-11 Laget: 2009-10-11 Sist oppdatert: 2017-12-13
    3. Scatter and detecability in lung SPECT: a Monte Carlo study
    Åpne denne publikasjonen i ny fane eller vindu >>Scatter and detecability in lung SPECT: a Monte Carlo study
    Vise andre…
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    The image quality in SPECT is degraded by scattered photons. The finite energy resolution of the gamma camera makes the detection of scattered photons unavoidable. The effect on the image is impaired contrast and a reduction in the possibilities of detecting small lesions.

    The detectability of cold lesions above statistical noise and normal variations in the activity distribution was evaluated using the Monte Carlo technique. A SPECT study of a digital thorax phantom was simulated with cold lesions of different sizes positioned inside the homogeneous activity distribution in the lungs. The contrast-to-noise for a number of energy window settings were assessed, with and without three different scatter correction methods: the dual-window, the triple-energy-window and the Klein-Nishina method.

    The contrast was improved by using scatter corrections and the TEW and KN scatter corrections showed the best result. The detectability was not improved by using scatter corrections when normal variations in the lung activity are small compared with the statistical noise level. Lesions of about 2 cm in diameter are detectable. The optimum energy window was found to be 128-154 keV, both with and without scatter corrections.

    Emneord
    Scatter correction, detectability, SPECT, Monte Carlo, lung
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-89581 (URN)
    Tilgjengelig fra: 2013-02-27 Laget: 2013-02-27 Sist oppdatert: 2013-02-27
    4. Attenuation correction in quantitative SPECT of cerebral blood flow: a Monte Carlo study
    Åpne denne publikasjonen i ny fane eller vindu >>Attenuation correction in quantitative SPECT of cerebral blood flow: a Monte Carlo study
    Vise andre…
    2000 (engelsk)Inngår i: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 45, nr 12, s. 3847-3859Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Monte Carlo simulation has been used to produce projections from a voxel-based brain phantom, simulating a 99mTc-HMPAO single photon emission computed tomography (SPECT) brain investigation. For comparison, projections free from the effects of attenuation and scattering were also simulated, giving ideal transaxial images after reconstruction. Three methods of attenuation correction were studied: (a) a pre-processing method, (b) a post-processing uniform method and (c) a post-processing non-uniform method using a density map. The accuracy of these methods was estimated by comparison of the reconstructed images with the ideal images using the normalized mean square error, NMSE, and quantitative values of the regional cerebral blood flow, rCBF. A minimum NMSE was achieved for the effective linear attenuation coefficient µeff = 0.07 (0.09) cm-1 for the uniformpre method, the effective mass attenuation coefficient µeff/ρ = 0.08 (0.10) cm2 g-1 for the uniformpost method and µeff/ρ = 0.12 (0.13) cm2 g-1 for the non-uniformpost method. Values in parentheses represent the case of dual-window scatter correction. The non-uniformpost method performed better, as measured by the NMSE, both with and without scatter correction. Furthermore, the non-uniformpost method gave, on average, more accurate rCBF values. Although the difference in rCBF accuracy was small between the various methods, the same method should be used for patient studies as for the reference material.

    sted, utgiver, år, opplag, sider
    Institute of Physics Publishing, 2000
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-79208 (URN)10.1088/0031-9155/45/12/324 (DOI)11131204 (PubMedID)
    Tilgjengelig fra: 2012-07-03 Laget: 2012-07-03 Sist oppdatert: 2017-12-07
    5. Dual-window scatter correction and energy window setting in cerebral blood flow SPECT: a Monte Carlo study
    Åpne denne publikasjonen i ny fane eller vindu >>Dual-window scatter correction and energy window setting in cerebral blood flow SPECT: a Monte Carlo study
    Vise andre…
    2000 (engelsk)Inngår i: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 45, nr 11, s. 3431-3440Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    The image quality in SPECT studies of the regional cerebral blood flow (rCBF) performed with 99mTc-HMPAO is degraded by scattered photons. The finite energy resolution of the gamma camera makes the detection of scattered photons unavoidable, and this is observed in the image as an impaired contrast between grey and white matter structures.

    In this work, a Monte Carlo simulated SPECT study of a realistic voxel-based brain phantom was used to evaluate the resulting contrast-to-noise ratio for a number of energy window settings, with and without the dual-window scatter correction. Values of the scaling factor k, used to obtain the fraction of scattered photons in the photopeak window, were estimated for each energy window.

    The use of a narrower, asymmetric, energy discrimination window improved the contrast, with a subsequent increase in statistical noise due to the lower number of counts. The photopeak-window setting giving the best contrast-to-noise ratio was found to be the same whether or not scatter correction was applied. Its value was 17% centred at 142 keV. At the optimum photopeak-window setting, the contrast was improved by using scatter correction, but the contrast-to-noise ratio was made worse.

    sted, utgiver, år, opplag, sider
    Institute of Physics Publishing, 2000
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-79207 (URN)10.1088/0031-9155/45/11/323 (DOI)11098915 (PubMedID)
    Tilgjengelig fra: 2012-07-03 Laget: 2012-07-03 Sist oppdatert: 2017-12-07
  • 8.
    Gustafsson, Agnetha
    et al.
    University of Göteborg, Sahlgrenska University Hospital.
    Bake, Björn
    University of Göteborg, Sahlgrenska University Hospital.
    Jacobsson, Lars
    University of Göteborg, Sahlgrenska University Hospital.
    Johansson, Åke
    University of Göteborg, Sahlgrenska University Hospital.
    Ljungberg, Michael
    University of Lund.
    Moonen, Michaela
    University of Göteborg, Sahlgrenska University Hospital.
    Attenueringseffekter vid SPECT av lungor1995Konferansepaper (Fagfellevurdert)
  • 9.
    Gustafsson, Agnetha
    et al.
    Department of Radiation Physics, University of Göteborg, Sahlgrenska University Hospital, Göteborg, Sweden .
    Bake, Björn
    Department of Clinical Physiology, University of Göteborg, Sahlgrenska University Hospital, Göteborg, Sweden .
    Jacobsson, Lars
    Department of Radiation Physics, University of Göteborg, Sahlgrenska University Hospital, Göteborg, Sweden .
    Johansson, Åke
    Department of Clinical Physiology, University of Göteborg, Sahlgrenska University Hospital, Göteborg, Sweden .
    Ljungberg, Michael
    Radiation Physics Department, University of Lund, Sweden .
    Moonen, Michaela
    Department of Clinical Physiology, University of Göteborg, Sahlgrenska University Hospital, Göteborg, Sweden .
    Evaluation of attenuation corrections using Monte Carlo simulated lung SPECT1998Inngår i: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 43, nr 8, s. 2325-2336Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    SPECT (single photon emission computed tomography) images are distorted by photon attenuation. The effect is complex in the thoracic region due to different tissue densities. This study compares the effect on the image homogeneity of two different methods of attenuation correction in lung SPECT; one pre-processing and one post-processing method. This study also investigates the impact of attenuation correction parameters such as lung contour, body contour, density of the lung tissue and effective attenuation coefficient. The Monte Carlo technique was used to simulate SPECT studies of a digital thorax phantom containing a homogeneous activity distribution in the lung. Homogeneity in reconstructed images was calculated as the coefficient of variation (CV). The isolated effect of the attenuation correction was assessed by normalizing pixel values from the attenuation corrected lung by pixel values from the lung with no attenuation effects. Results show that the CV decreased from 12.8% with no attenuation correction to 4.4% using the post-processing method and true densities in the thoracic region. The impact of variations in the definition of the body contour was found to be marginal while the corresponding effect of variations in the lung contour was substantial.

  • 10.
    Gustafsson, Agnetha
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Enander, Annika
    Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    Evaluation of the reconstruction algorithms for two different matrix sizes: OSEM and Evolution Cardiac for myocardial SPECT.2010Konferansepaper (Fagfellevurdert)
  • 11.
    Gustafsson, Agnetha
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Enander, Annika
    Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    Utvärdering av OSEM och Evolution for Cardiac med två olika matrisstorlekar; för myokardscintigrafi med SPECT.2010Konferansepaper (Annet vitenskapelig)
  • 12.
    Gustafsson, Agnetha
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Grétarsdóttir, Jakobina
    Sahlgrenska Universitetssjukhuset, Göteborg.
    Which collimator should be used for myocardial perfusion SPECT, HR or GP?2006Konferansepaper (Annet vitenskapelig)
  • 13.
    Gustafsson, Agnetha
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Jacobsson, Lars
    University of Göteborg, Sahlgrenska University Hospital.
    Johansson, Åke
    University of Göteborg, Sahlgrenska University Hospital.
    Moonen, Michaela
    University of Göteborg, Sahlgrenska University Hospital.
    Tylén, Ulf
    University of Göteborg.
    Bake, Björn
    University of Göteborg, Sahlgrenska University Hospital.
    Attenueringseffekter vid lung-SPECT av friska försökspersoner1999Konferansepaper (Annet vitenskapelig)
  • 14.
    Gustafsson, Agnetha
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    Jacobsson, Lars
    Department of Radiation Physics, University of Göteborg, Sahlgrenska University Hospital, Göteborg, Sweden.
    Johansson, Åke
    Department of Clinical Physiology, University of Göteborg, Sahlgrenska University Hospital, Göteborg, Sweden.
    Moonen, Michaela
    Department of Lung Medicine, University of Göteborg, Sahlgrenska University Hospital, Göteborg, Sweden.
    Tylén, Ulf
    Department of Radiology, University of Göteborg, Sahlgrenska University Hospital, Göteborg, Sweden.
    Bake, Björn
    Department of Lung Medicine, University of Göteborg, Sahlgrenska University Hospital, Göteborg, Sweden.
    Evaluation of various attenuation corrections in lung SPECT in healthy subjects2003Inngår i: Nuclear medicine communications, ISSN 0143-3636, E-ISSN 1473-5628, Vol. 24, nr 10, s. 1087-1095Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of increasingly more sophisticated attenuation correction methods on image homogeneity has been studied in seven healthy subjects. The subjects underwent computed tomography (CT), single photon emission computed tomography (SPECT) and transmission computed tomography (TCT) of the thorax region in the supine position. Density maps were obtained from the CT and TCT studies. Attenuation corrections were performed using five different methods: (1) uniform correction using only the body contour, (2) TCT based corrections using the average lung density, (3) TCT based corrections using the pixel density, (4) CT based corrections using average lung density, and (5) CT based corrections using the pixel density. The isolated attenuation effects were assessed on quotient images generated by the division of images obtained using various attenuation correction methods divided by the non-uniform attenuation correction based on CT pixel density (reference method). The homogeneity was calculated as the coefficient of variation of the quotient images (CVatt), showing the isolated attenuation effects. Values of CVatt were on average 12.8% without attenuation correction, 10.7% with the uniform correction, 8.1% using TCT map using the average lung density value and 4.8% using CT and average lung density corrections. There are considerable inhomogeneities in lung SPECT slices due to the attenuation effect. After attenuation correction the remaining inhomogeneity is considerable and cannot be explained by statistical noise and camera non-uniformity alone.

  • 15.
    Gustafsson, Agnetha
    et al.
    Department of Radiation Physics, Göteborg University, Sweden.
    Jonsson, Cathrine
    Department of Hospital Physics, Section for Nuclear Medicine, Karolinska Hospital, Stockholm, Sweden.
    Ljungberg, Michael
    Radiation Physics Department, Lund University, The Jubileum Institute, Lund, Sweden.
    Bake, Björn
    Department of Respiratory Medicine and Allergology, Göteborg University, Göteborg, Sweden.
    Jacobsson, Lars
    Department of Radiation Physics, Göteborg University, Sweden.
    Scatter and detecability in lung SPECT: a Monte Carlo studyManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    The image quality in SPECT is degraded by scattered photons. The finite energy resolution of the gamma camera makes the detection of scattered photons unavoidable. The effect on the image is impaired contrast and a reduction in the possibilities of detecting small lesions.

    The detectability of cold lesions above statistical noise and normal variations in the activity distribution was evaluated using the Monte Carlo technique. A SPECT study of a digital thorax phantom was simulated with cold lesions of different sizes positioned inside the homogeneous activity distribution in the lungs. The contrast-to-noise for a number of energy window settings were assessed, with and without three different scatter correction methods: the dual-window, the triple-energy-window and the Klein-Nishina method.

    The contrast was improved by using scatter corrections and the TEW and KN scatter corrections showed the best result. The detectability was not improved by using scatter corrections when normal variations in the lung activity are small compared with the statistical noise level. Lesions of about 2 cm in diameter are detectable. The optimum energy window was found to be 128-154 keV, both with and without scatter corrections.

  • 16.
    Gustafsson, Agnetha
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Ärlig, Åsa
    Göteborg University, Sahlgrenska University Hospital.
    Jacobsson, Lars
    Göteborg University, Sahlgrenska University Hospital.
    Ljungberg, Michael
    Lund University.
    Wikkelsö, Carsten
    Göteborg University, Sahlgrenska University Hospital.
    Comptonbaserad spridningskorrektion och energifönsterinställning vid CBF SPECT: En Monte Carlo studie2000Konferansepaper (Annet vitenskapelig)
  • 17.
    Gustafsson, Agnetha
    et al.
    Department of Radiation Physics, Göteborg University, Sahlgrenska University Hospital, Göteborg, Sweden .
    Ärlig, Åsa
    Department of Radiation Physics, Göteborg University, Sahlgrenska University Hospital, Göteborg, Sweden .
    Jacobsson, Lars
    Department of Radiation Physics, Göteborg University, Sahlgrenska University Hospital, Göteborg, Sweden .
    Ljungberg, Michael
    Radiation Physics Department, Lund University, The Jubileum Institute, Lund, Sweden .
    Wikkelsö, Carsten
    Institute of Clinical Neuroscience, Göteborg University, Sahlgrenska University Hospital, Göteborg, Sweden .
    Dual-window scatter correction and energy window setting in cerebral blood flow SPECT: a Monte Carlo study2000Inngår i: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 45, nr 11, s. 3431-3440Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The image quality in SPECT studies of the regional cerebral blood flow (rCBF) performed with 99mTc-HMPAO is degraded by scattered photons. The finite energy resolution of the gamma camera makes the detection of scattered photons unavoidable, and this is observed in the image as an impaired contrast between grey and white matter structures.

    In this work, a Monte Carlo simulated SPECT study of a realistic voxel-based brain phantom was used to evaluate the resulting contrast-to-noise ratio for a number of energy window settings, with and without the dual-window scatter correction. Values of the scaling factor k, used to obtain the fraction of scattered photons in the photopeak window, were estimated for each energy window.

    The use of a narrower, asymmetric, energy discrimination window improved the contrast, with a subsequent increase in statistical noise due to the lower number of counts. The photopeak-window setting giving the best contrast-to-noise ratio was found to be the same whether or not scatter correction was applied. Its value was 17% centred at 142 keV. At the optimum photopeak-window setting, the contrast was improved by using scatter correction, but the contrast-to-noise ratio was made worse.

  • 18.
    Karlsson, Henrik
    et al.
    Med radiofysik IMV.
    Angland, Erik
    Linköpings universitet, Institutionen för medicin och vård.
    Davidsson, Anette
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Klinisk fysiologi. Östergötlands Läns Landsting, Hjärtcentrum, Fysiologiska kliniken.
    Gustafsson, Agneta
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Pettersson, Håkan
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Measurements of airborne 99mTc to technologists during technegas ventilation studies2006Inngår i: EANM,2006, 2006Konferansepaper (Annet vitenskapelig)
  • 19.
    Karlsson, Henrik
    et al.
    Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Gustafsson, Agnetha
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Fingerdosmätningar vid olika moment vid hantering av 18F-FDG2008Konferansepaper (Annet vitenskapelig)
  • 20.
    Karlsson, Henrik
    et al.
    Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Lindblom, Gunnar
    Östergötlands Läns Landsting, Diagnostikcentrum, Röntgenkliniken i Linköping.
    Brundin, Helene
    Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    Gustafsson, Agnetha
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Optimering av dosering vid skelettscintigrafi – en VGC-studie2008Konferansepaper (Annet vitenskapelig)
  • 21.
    Kvernby, Sofia
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik.
    Olsson, Anna
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    Gustafsson, Agnetha
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Opimization of activity level in rCBF SPECT using observer study Visual Grading Regression2012Konferansepaper (Annet vitenskapelig)
  • 22.
    Lundell, Marie
    et al.
    Radiumhemmet, Karolinska Hospital, Stockholm.
    Mattsson, Anders
    Radiumhemmet, Karolinska Hospital, Stockholm.
    Karlsson, Per
    Sahlgrenska University Hospital, Gothenburg.
    Holmberg, Erik
    Sahlgrenska University Hospital, Gothenburg.
    Gustafsson, Agnetha
    Sahlgrenska University Hospital, Gothenburg.
    Holm, Lars-Erik
    Swedish Radiation Protection Institute, Solna.
    Breast cancer risk after radiotherapy in infancy: a pooled analysis of two Swedish cohorts of 17,202 infants1999Inngår i: Radiation Research, ISSN 0033-7587, E-ISSN 1938-5404, Vol. 151, nr 5, s. 626-632Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The incidence of breast cancer was studied in a cohort of 17,202 women irradiated for skin hemangioma in infancy at the Radiumhemmet, Stockholm, or the Sahlgrenska University Hospital, Gothenburg. A major part of the cohort had been treated with radium-226 applicators, and the mean absorbed dose to the breasts was 0.29 Gy (range <0.01-35.8 Gy). Two hundred forty-five breast cancers were diagnosed in the cohort during the period 1958-1993, and the standardized incidence ratio (SIR) was 1.20 (95% CI 1.06-1.36). Different dose-response models were tested, and a linear model gave the best fit. Neither age at exposure, breast dose rate, ovarian dose nor time since exposure had any statistically significant modifying effect, and breast dose was the only determinant of risk. The excess relative risk per gray (ERR/Gy) was 0.35 (95% CI 0.18-0.59), which is lower than in most other studies.

  • 23.
    Nilsson, Kerstin A
    et al.
    Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    Karlsson, Henrik
    Linköpings universitet, Institutionen för medicin och hälsa. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Lindblom, Gunnar
    Östergötlands Läns Landsting, Diagnostikcentrum, Röntgenkliniken i Linköping.
    Gustafsson, Agnetha
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Kartläggning av bildkvalitetsparametrar vid skelettscintigrafi2010Konferansepaper (Annet vitenskapelig)
  • 24.
    Norberg, Pernilla
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen. Linköpings universitet, Hälsouniversitetet.
    Bake, Björn
    Sahlgrenska universitetssjukhuset, Göteborg.
    Jacobsson, Lars
    Göteborgs universitet, Göteborg.
    Alm Carlsson, Gudrun
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Gustafsson, Agnetha
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen. Linköpings universitet, Hälsouniversitetet.
    Evaluation of reconstruction techniques for lung single photon emission tomography: A Monte Carlo study2007Inngår i: Nuclear medicine communications, ISSN 0143-3636, E-ISSN 1473-5628, Vol. 28, nr 12, s. 929-936Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    BACKGROUND: In studies of the distribution of lung function, the image quality of lung single photon emission computed tomography (SPECT) is important and one factor influencing it is the reconstruction algorithm. AIM: To systematically evaluate ordered subsets expectation maximization (OSEM) and compare it with filtered back-projection (FBP) for lung SPECT with Tc. METHODS: The evaluation of the number of iterations used in OSEM was based on the image quality parameter contrast. The comparison between OSEM and FBP was based on trade-off plots between statistical noise and spatial resolution for different filter parameters, collimators and count-levels. A Monte Carlo technique was used to simulate SPECT studies of a digital thorax phantom containing two sets of activity: one with a homogeneous activity distribution within the lungs and the other with superposed high- and low-activity objects. Statistical noise in the reconstructed images was calculated as the coefficient of variation (CV) and spatial resolution as full width at half-maximum (FWHM). RESULTS: For the configuration studied, the OSEM reconstruction in combination with post-filtering should be used in lung SPECT studies with at least 60 MLEM equivalent iterations. Compared to FBP the spatial resolution was improved by about 1 mm. For a constant level of CV, a four-fold increase in count level resulted in an increased resolution of about 2 mm. Spatial resolution and cut-off frequency depends on what value of noise in the image is acceptable also increased by using a low-energy, high-resolution collimator for CV values above 3%. The choice of noise-reducing filter and cut-off frequency depends on what value of noise in the image is acceptable.

  • 25.
    Norberg, Pernilla
    et al.
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Olsson, Anna
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Medicinska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Alm Carlsson, Gudrun
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Medicinska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Sandborg, Michael
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Medicinska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Gustafsson, Agneta
    Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US. Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Medicinska fakulteten.
    Optimisation of quantitative lung SPECT applied to mild COPD: a software phantom simulation study2015Inngår i: EJNMMI research, ISSN 2191-219X, Vol. 5, nr 16Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    BACKGROUND: The amount of inhomogeneities in a (99m)Tc Technegas single-photon emission computed tomography (SPECT) lung image, caused by reduced ventilation in lung regions affected by chronic obstructive pulmonary disease (COPD), is correlated to disease advancement. A quantitative analysis method, the CVT method, measuring these inhomogeneities was proposed in earlier work. To detect mild COPD, which is a difficult task, optimised parameter values are needed.

    METHODS: In this work, the CVT method was optimised with respect to the parameter values of acquisition, reconstruction and analysis. The ordered subset expectation maximisation (OSEM) algorithm was used for reconstructing the lung SPECT images. As a first step towards clinical application of the CVT method in detecting mild COPD, this study was based on simulated SPECT images of an advanced anthropomorphic lung software phantom including respiratory and cardiac motion, where the mild COPD lung had an overall ventilation reduction of 5%.

    RESULTS: The best separation between healthy and mild COPD lung images as determined using the CVT measure of ventilation inhomogeneity and 125 MBq (99m)Tc was obtained using a low-energy high-resolution collimator (LEHR) and a power 6 Butterworth post-filter with a cutoff frequency of 0.6 to 0.7 cm(-1). Sixty-four reconstruction updates and a small kernel size should be used when the whole lung is analysed, and for the reduced lung a greater number of updates and a larger kernel size are needed.

    CONCLUSIONS: A LEHR collimator and 125 (99m)Tc MBq together with an optimal combination of cutoff frequency, number of updates and kernel size, gave the best result. Suboptimal selections of either cutoff frequency, number of updates and kernel size will reduce the imaging system's ability to detect mild COPD in the lung phantom.

  • 26.
    Norberg, Pernilla
    et al.
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Olsson, Anna
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Hälsouniversitetet.
    Alm Carlsson, Gudrun
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Hälsouniversitetet.
    Sandborg, Michael
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Gustafsson, Agnetha
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Optimisation of quantitative lung SPECT applied to mild COPD: a Monte Carlo-based analysis2014Manuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    The amount of inhomogeneities in a single photon emission computed tomography (SPECT) lung image, caused by reduced ventilation in lung regions affected by chronic obstructive pulmonary disease (COPD), is correlated to disease advancement. A quantitative analysis method, the CVT-method, measuring these inhomogeneities was proposed in earlier work (Norberg et al., 2013). To detect mild COPD, which is a difficult task, optimized parameter values are needed. In this work, the CVT-method was optimized with respect to the parameter values of acquisition, reconstruction and analysis. The ordered subset expectation maximization (OSEM) algorithm was used for reconstructing the lung SPECT images. As a first step towards clinical application of the CVT-method in detecting mild COPD, this study was based on simulated SPECT images of an advanced anthropomorphic lung phantom including respiratory and cardiac motion, where the mild COPD lung had an overall ventilation reduction of 5%. The largest separation between healthy and mild COPD lung images as determined using the CVT-measure of ventilation inhomogeneity and 125 MBq 99mTc was obtained using a low-energy high-resolution collimator and a Butterworth postfilter with a cut-off frequency of 0.6-0.7 cm-1. Sixty-four reconstruction updates should be used when the whole lung is analysed and for the reduced lung a greater number of updates is needed.

  • 27.
    Norberg, Pernilla
    et al.
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Persson, H Lennart
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för kardiovaskulär medicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Lungmedicinska kliniken US.
    Schmekel, Birgitta
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för kardiovaskulär medicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    Alm Carlsson, Gudrun
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Hälsouniversitetet.
    Wahlin, Karl
    Linköpings universitet, Institutionen för datavetenskap, Statistik. Linköpings universitet, Filosofiska fakulteten.
    Sandborg, Michael
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Gustafsson, Agnetha
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Does quantitative lung SPECT detect lung abnormalities earlier than lung function tests?: Results of a pilot study2014Inngår i: EJNMMI Research, ISSN 2191-219X, E-ISSN 2191-219X, Vol. 4, nr 39, s. 1-12Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Heterogeneous ventilation in lungs of allergic individuals, cigarette smokers, asthmatics and chronic obstructive pulmonary disease (COPD) patients has been demonstrated using imaging modalities such as PET, MR and SPECT. These individuals suffer from narrow and/or closed airways to various extents. By calculating regional heterogeneity in lung ventilation SPECT images as the coefficient of variation (CV) in small elements of the lung, heterogeneity maps and CV-frequency curves can be generated and used to quantitatively measure heterogeneity. This work explores the potential to use such measurements to detect mild ventilation heterogeneities in lung healthy subjects.

    Method: Fourteen healthy subjects without documented lung disease or respiratory symptoms, and two patients with documented airway disease, inhaled on average approximately 90 MBq 99mTc-Technegas immediately prior to the 20 min SPECT acquisition. Variation in activity uptake between subjects was compensated for in resulting CV values. The area under the compensated CV frequency curve (AUC), for CV values greater than a threshold value CVT, AUC(CV> CVT), was used as the measure of ventilation heterogeneity.

    Results: Patients with lung function abnormalities, according to lung function tests, generated higher AUC(CV>20%) values compared to healthy subjects (p=0.006). Strong linear correlations with the AUC(CV>20%) values were found for age (p=0.006) and height (p=0.001). These demonstrated that ventilation heterogeneities increased with age and that they depend on lung size. Strong linear correlations were found for the lung function value related to indices of airway closure/air trapping, RV/TLC (p=0.009), and DLCOc (p=0.009), a value partly related to supposed ventilation/perfusion mismatch. These findings support the association between conventional lung function tests and the AUC(CV>20%) value.

    Conclusions: Among the healthy subjects there is a group with increased AUC(CV>20%) values, but with normal lung function tests, which implies that it might be possible to differentiate ventilation heterogeneities earlier in a disease process than by lung function tests.

  • 28.
    Norberg, Pernilla
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Persson, Hans Lennart
    Linköpings universitet, Institutionen för medicin och hälsa, Lungmedicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Lungmedicinska kliniken US.
    Alm Carlsson, Gudrun
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Bake, Björn
    Sahlgrenska Academy at University of Gothenburg.
    Kentson, Magnus
    Ryhov Hospital.
    Sandborg, Michael
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Gustafsson, Agnetha
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    Quantitative lung SPECT applied on simulated early COPD and humans with advanced COPD2013Inngår i: EJNMMI Research, ISSN 2191-219X, E-ISSN 2191-219X, Vol. 3, nr 28Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    BACKGROUND:Reduced ventilation in lung regions affected by chronic obstructive pulmonary disease (COPD), reflected as inhomogeneities in the single-photon emission computed tomography (SPECT) lung image, is correlated to disease advancement. An analysis method for measuring these inhomogeneities is proposed in this work. The first aim was to develop a quantitative analysis method that could discriminate between Monte Carlo simulated normal and COPD lung SPECT images. A second aim was to evaluate the ability of the present method to discriminate between human subjects with advanced COPD and healthy volunteers.

    METHODS:In the simulated COPD study, different activity distributions in the lungs were created to mimic the healthy lung (normal) and different levels of COPD. Gamma camera projections were Monte Carlo simulated, representing clinically acquired projections of a patient who had inhaled 125 MBq 99mTc-Technegas followed by a 10-min SPECT examination. Reconstructions were made with iterative ordered subset expectation maximisation. The coefficient of variance (CV) was calculated for small overlapping volumes covering the 3D reconstructed activity distribution. A CV threshold value (CVT) was calculated as the modal value of the CV distribution of the simulated normal. The area under the distribution curve (AUC), for CV values greater than CVT, AUC(CVT), was then calculated. Moreover, five patients with advanced emphysema and five healthy volunteers inhaled approximately 75 MBq 99mTc-Technegas immediately before the 20-min SPECT acquisition. In the human study, CVT was based on the mean CV distribution of the five healthy volunteers.

    RESULTS:A significant difference (p < 0.001) was found between the Monte-Carlo simulated normal and COPD lung SPECT examinations. The present method identified a total reduction of ventilation of approximately 5%, not visible to the human eye in the reconstructed image. In humans the same method clearly discriminated between the five healthy volunteers and five patients with advanced COPD (p < 0.05).

    CONCLUSIONS:While our results are promising, the potential of the AUC(CVT) method to detect less advanced COPD in patients needs further clinical studies.

  • 29.
    Norberg, Pernilla
    et al.
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Persson, Lennart
    Linköpings universitet, Institutionen för medicin och hälsa, Lungmedicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Lungmedicinska kliniken US.
    Schmekel, Birgitte
    Linköpings universitet, Institutionen för medicin och hälsa, Klinisk fysiologi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    Sandborg, Michael
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Kentson, Magnus
    Lungmedicin, Länsjukhuset Ryhov, Jönköping.
    Gustafsson, Agnetha
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    The potential of quantitative lung SPECT in identifying humans with COPD using the CVT-method: a Pilot Study of advance disease2012Konferansepaper (Annet vitenskapelig)
  • 30.
    Norberg, Pernilla
    et al.
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    Sandborg, Michael
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Alm Carlsson, Gudrun
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Gustafsson, Agnetha
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Persson, Lennart
    Linköpings universitet, Institutionen för medicin och hälsa, Lungmedicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Lungmedicinska kliniken US.
    Bake, Björn
    Avdelningen för intermedicin, Institutionen för medicin, Sahlgrenska Akademin vid Göteborgs Universitet, Göteborg.
    Kentson, Magnus
    Avdelningen för Lungmedicin, Länssjukhuset Ryhov, Jönköping .
    Quantitative lung-SPECT applied on simulated early COPD and humans with advanced COPD2012Konferansepaper (Annet vitenskapelig)
  • 31.
    Norberg, Pernilla
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Sandborg, Michael
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Bake, Björn
    Sahlgrenska universitetssjukhuset, Göteborg.
    Gustafsson, Agnetha
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    The potential of lung SPECT in identifying humans with early stages of COPD: a Monte Carlo-based analysis2011Konferansepaper (Annet vitenskapelig)
  • 32.
    Ohlson, Maria
    et al.
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och hälsa. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Grétarsdóttir, Jakobína
    Sahlgrenska Universitetssjukhuset.
    Olsson, Eva
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och hälsa. Östergötlands Läns Landsting, Hjärtcentrum, Fysiologiska kliniken.
    Johansson, Lena
    Sahlgrenska Universitetssjukhuset.
    Gustafsson, Agneta
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och hälsa. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Kartläggning av bildkvalitet vid myokardscintifrafi: en nationell studie2008Rapport (Annet vitenskapelig)
    Abstract [sv]

     www.ssi.se Statens strålsskyddsinstitut Swedish Radiation Protection Authority.

  • 33. Ohlsson, Maria
    et al.
    Grétarsdóttir, Jakobina
    Sahlgrenska Universitetssjukhuset, Göteborg.
    Olsson, Eva
    Linköpings universitet, Institutionen för medicin och hälsa, Klinisk fysiologi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    Johansson, Lena
    Gustafsson, Agnetha
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Image quality survey and evaluation of myocardial perfusion SPECT: a national study2007Konferansepaper (Annet vitenskapelig)
  • 34. Ohlsson, Maria
    et al.
    Grétarsdóttir, Jakobina
    Sahlgrenska Universitetssjukhuset, Göteborg.
    Olsson, Eva
    Linköpings universitet, Institutionen för medicin och hälsa, Klinisk fysiologi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    Johansson, Lena
    Gustafsson, Agnetha
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Kartläggning och utvärdering av bildkvalitet vid myokard SPECT - En nationell studie2007Konferansepaper (Annet vitenskapelig)
  • 35.
    Olsson, Anna
    et al.
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiofysik.
    Davidsson, Anette
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Klinisk fysiologi. Östergötlands Läns Landsting, Hjärtcentrum, Fysiologiska kliniken.
    Pettersson, Håkan
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Gustafsson, Agneta
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Finger doses from handling radioative isotopes at a Nuclear Medicine department2006Inngår i: EANM,2006, 2006Konferansepaper (Annet vitenskapelig)
  • 36.
    Olsson, Anna
    et al.
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiofysik.
    Gustafsson, Agneta
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Hellerström, Sabine
    Klinsik Fysiologi HC.
    Granerus, Göran
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Klinisk fysiologi. Östergötlands Läns Landsting, Hjärtcentrum, Fysiologiska kliniken.
    World Federation of Nuclear Medicine and Biology Santiago, Chile, 20022002Inngår i: World Federation of Nuclear Medicine and Biology Santiago, Chile 2002,2002, 2002Konferansepaper (Annet vitenskapelig)
    Abstract [en]

       

  • 37.
    Olsson, Anna
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Nilsson, Kerstin A
    Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    Lindblom, Gunnar
    Östergötlands Läns Landsting, Diagnostikcentrum, Röntgenkliniken i Linköping.
    Karlsson, Henrik
    Linköpings universitet, Institutionen för medicin och hälsa. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Gustafsson, Agnetha
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Bedömning av bildkvalitet med hjälp av VGC på helkroppsscanning vid skelettscintigrafi2010Konferansepaper (Annet vitenskapelig)
  • 38.
    Olsson, Anna
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Sundström, Torbjörn
    Umeå universitet .
    Larsson, Anne
    Umeå universitet .
    Sandborg, Michael
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Gustafsson, Agnetha
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    A strategy for optimisation of nuclear medicine examinations – application to rCBF SPECT2010Konferansepaper (Annet vitenskapelig)
  • 39.
    Olsson, Anna
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen. Linköpings universitet, Hälsouniversitetet.
    Ärlig, Åsa
    County Hospital Ryhov, Jönköping.
    Alm Carlsson, Gudrun
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Gustafsson, Agnetha
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen. Linköpings universitet, Hälsouniversitetet.
    Evaluation of reconstruction techniques in regional cerebral blood flow SPECT using trade-off plots: A Monte Carlo study2007Inngår i: Nuclear medicine communications, ISSN 0143-3636, E-ISSN 1473-5628, Vol. 28, nr 9, s. 719-725Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    BACKGROUND AND AIM: The image quality of single photon emission computed tomography (SPECT) depends on the reconstruction algorithm used. The purpose of the present study was to evaluate parameters in ordered subset expectation maximization (OSEM) and to compare systematically with filtered back-projection (FBP) for reconstruction of regional cerebral blood flow (rCBF) SPECT, incorporating attenuation and scatter correction. METHODS: The evaluation was based on the trade-off between contrast recovery and statistical noise using different sizes of subsets, number of iterations and filter parameters. Monte Carlo simulated SPECT studies of a digital human brain phantom were used. The contrast recovery was calculated as measured contrast divided by true contrast. Statistical noise in the reconstructed images was calculated as the coefficient of variation in pixel values. RESULTS: A constant contrast level was reached above 195 equivalent maximum likelihood expectation maximization iterations. The choice of subset size was not crucial as long as there were > or = 2 projections per subset. The OSEM reconstruction was found to give 5-14% higher contrast recovery than FBP for all clinically relevant noise levels in rCBF SPECT. The Butterworth filter, power 6, achieved the highest stable contrast recovery level at all clinically relevant noise levels. The cut-off frequency should be chosen according to the noise level accepted in the image. CONCLUSION: Trade-off plots are shown to be a practical way of deciding the number of iterations and subset size for the OSEM reconstruction and can be used for other examination types in nuclear medicine.

  • 40.
    Ressner, Marcus
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Gustafsson, Disa
    Karolinska Institutet, Stockholm.
    Gustafsson, Agnetha
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Jonsson, Cathrine
    Karolinska universitetssjukhuset Solna, Stockholm.
    Experimental evaluation of iterative reconstruction for whole-body F-18 PET in a 3- and 4-ring PET/CT system2011Konferansepaper (Annet vitenskapelig)
  • 41.
    Sandborg, Michael
    et al.
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Nilsson Althen, Jonas
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Gustafsson, Agneta
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    EFFICIENT QUALITY ASSURANCE PROGRAMS IN RADIOLOGY AND NUCLEAR MEDICINE IN ÖSTERGÖTLAND, SWEDEN2010Inngår i: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 139, nr 1-3, s. 410-417Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Owners of imaging modalities using ionising radiation should have a documented quality assurance (QA) program, as well as methods to justify new radiological procedures to ensure safe operation and adequate clinical image quality. This includes having a system for correcting divergences, written imaging protocols, assessment of patient and staff absorbed doses and a documented education and training program. In this work, how some aspects on QA have been implemented in the County of Östergötland in Sweden, and efforts to standardise and automate the process as an integrated part of the radiology and nuclear medicine QA programs were reviewed. Some key performance parameters have been identified by a Swedish task group of medical physicists to give guidance on selecting relevant QA methods. These include low-contrast resolution, image homogeneity, automatic exposure control, calibration of air kerma-area product metres and patient–dose data registration in the radiological information system, as well as the quality of reading stations and of the transfer of images to the picture archive and communication system. IT-driven methods to automatically assess patient doses and other data on all examinations are being developed and evaluated as well as routines to assess clinical image quality by use of European quality criteria. By assessing both patient absorbed doses and clinical image quality on a routine basis, the medical physicists in our region aim to be able to spend more time on imaging optimisation and less time on periodic testing of the technical performance of the equipment, particularly on aspects that show very few divergences. The role of the Medical Physics Expert is rapidly developing towards a person doing advanced data-analysis and giving scientific support rather than one performing mainly routine periodic measurements. It is concluded that both the European Council directive and the rapid development towards more complex diagnostic imaging systems and procedures support this changing role of the medical physics professional.

  • 42.
    Sandborg, Michael
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Nilsson Althen, Jonas
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Gustafsson, Agnetha
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Efficient quality assurance in radiology and Nuclear Medicine2010Konferansepaper (Annet vitenskapelig)
  • 43.
    Toll, Pia
    et al.
    Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    Olsson, Eva
    Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    Gustafsson, Agnetha
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Erfarenheter från avvikelsehantering i Linköping2010Konferansepaper (Annet vitenskapelig)
  • 44.
    Xu, Jiahua
    et al.
    Sahlgrenska University Hospital, Göteborg.
    Moonen, Mchaela
    Sahlgrenska University Hospital, Göteborg.
    Johansson, Åke
    Sahlgrenska University Hospital, Göteborg.
    Gustafsson, Agnetha
    Sahlgrenska University Hospital, Göteborg.
    Bake, Björn
    Sahlgrenska University Hospital, Göteborg.
    Quantitative analysis of inhomogeneity in ventilation SPET2001Inngår i: European Journal of Nuclear Medicine, ISSN 0340-6997, E-ISSN 1432-105X, Vol. 28, nr 12, s. 1795-1800Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this study was to evaluate a method for quantification of inhomogeneity in ventilation single-photon emission tomography (SPET). Nine emphysematous patients, nine life-long non-smokers and nine smokers were included in the study. The SPET investigation was performed after 50 MBq (99m)Tc-Technegas had been inhaled by each subject in the supine position. A single-head gamma camera, equipped with a general-purpose parallel-hole collimator using 64 projections (20 s each) over 360 degrees, was used. Data were acquired in 128x128 matrices. Attenuation correction was applied based upon computed tomography (CT) density maps. Lung regions of interest were delineated manually on CT images and then positioned on SPET images. Several attenuation-corrected transaxial SPET slices (thickness 1 cm, spacing 3.5 cm) were reconstructed. Each SPET slice was divided into several 2x2x1 cm(3) elements. Inhomogeneity was assessed by the coefficient of variation (CV) of the pixel counts within these elements (micro-level) and the CV of the total counts of the elements (macro-level). Micro-level CVs in non-smokers varied between 1% and 41%, whereas they were dispersed over a wide range (1%-600%) in emphysematous patients. In seven smokers, the frequency distribution of micro-level CVs was within the normal range, whereas in the other two smokers the values were between the normal range and the range in emphysematous patients. The pooled mean values of micro-level CVs and macro-level CVs in each subject clearly separated the patients from the others. Parametric images of micro-level CV indicated the localisation and severity of ventilation inhomogeneity. We conclude that the present method enables quantification and localisation of regional inhomogeneity in ventilation SPET images.

  • 45.
    Xu, Jiahua
    et al.
    Sahlgrenska University Hospital, Göteborg.
    Moonen, Michaela
    Sahlgrenska University Hospital, Göteborg.
    Johansson, Åke
    Sahlgrenska University Hospital, Göteborg.
    Gustafsson, Agnetha
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Bake, Björn
    Sahlgrenska University Hospital, Göteborg.
    Quantitative analysis oh inhomogenity in ventilation SPECT2002Konferansepaper (Annet vitenskapelig)
  • 46.
    Ärlig, Åsa
    et al.
    Department of Radiation Physics, Göteborg University, Sahlgrenska University Hospital, Göteborg, Sweden .
    Gustafsson, Agnetha
    Department of Radiation Physics, Göteborg University, Sahlgrenska University Hospital, Göteborg, Sweden .
    Jacobsson, Lars
    Department of Radiation Physics, Göteborg University, Sahlgrenska University Hospital, Göteborg, Sweden .
    Ljungberg, Michael
    Radiation Physics Department, Lund University, The Jubileum Institute, Lund, Sweden .
    Wikkelsö, Carsten
    Institute of Clinical Neuroscience, Göteborg University, Sahlgrenska University Hospital, Göteborg, Sweden .
    Attenuation correction in quantitative SPECT of cerebral blood flow: a Monte Carlo study2000Inngår i: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 45, nr 12, s. 3847-3859Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Monte Carlo simulation has been used to produce projections from a voxel-based brain phantom, simulating a 99mTc-HMPAO single photon emission computed tomography (SPECT) brain investigation. For comparison, projections free from the effects of attenuation and scattering were also simulated, giving ideal transaxial images after reconstruction. Three methods of attenuation correction were studied: (a) a pre-processing method, (b) a post-processing uniform method and (c) a post-processing non-uniform method using a density map. The accuracy of these methods was estimated by comparison of the reconstructed images with the ideal images using the normalized mean square error, NMSE, and quantitative values of the regional cerebral blood flow, rCBF. A minimum NMSE was achieved for the effective linear attenuation coefficient µeff = 0.07 (0.09) cm-1 for the uniformpre method, the effective mass attenuation coefficient µeff/ρ = 0.08 (0.10) cm2 g-1 for the uniformpost method and µeff/ρ = 0.12 (0.13) cm2 g-1 for the non-uniformpost method. Values in parentheses represent the case of dual-window scatter correction. The non-uniformpost method performed better, as measured by the NMSE, both with and without scatter correction. Furthermore, the non-uniformpost method gave, on average, more accurate rCBF values. Although the difference in rCBF accuracy was small between the various methods, the same method should be used for patient studies as for the reference material.

1 - 46 of 46
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