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  • 151.
    Ragnehed, Mattias
    et al.
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiologi. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Håkansson, Irene
    Nilsson, Maritha
    Lundberg, Peter
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Söderfeldt, Birgitta
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Engström, Maria
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiologi. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Influence of Diazepam on clinically designed fMRI2006Ingår i: American Neuropsyciatric Association annual meeting,2006, 2006Konferensbidrag (Övrigt vetenskapligt)
  • 152.
    Ragnehed, Mattias
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiologi. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Hälsouniversitetet.
    Håkansson, Irene
    Linköpings universitet, Institutionen för nervsystem och rörelseorgan. Linköpings universitet, Hälsouniversitetet.
    Nilsson, Maritha
    National Board of Forensic Sciences, Linköping.
    Lundberg, Peter
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiologi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen. Östergötlands Läns Landsting, Bildmedicinskt centrum, Röntgenkliniken i Linköping.
    Söderfeldt, Birgitta
    Department of Clinical Science and Education, Sodersjukhuset, Karolinska Institutet, Stockholm, Sweden.
    Engström, Maria
    Linköpings universitet, Institutionen för medicinsk teknik, Centrum för medicinsk bildvetenskap och visualisering. Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiologi. Linköpings universitet, Hälsouniversitetet.
    Influence of diazepam on clinically designed FMRI2007Ingår i: The Journal of Neuropsychiatry and Clinical Neurosciences, ISSN 0895-0172, E-ISSN 1545-7222, Vol. 19, nr 2, s. 164-172Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The authors investigated the effect of diazepam on clinically relevant measures from functional magnetic resonance imaging (fMRI) examinations. Twenty volunteers were scanned twice. Using a double-blind randomized study design, the volunteers received placebo on one occasion, and on the other, 5 mg of diazepam. Three functional tests were used: motor, word generation, and working memory. Images were analyzed individually for each subject and the number of activated voxels and the laterality index were calculated. No significant effects related to the drug were detected. In contrast, the motor and working memory tasks showed a significant decrease in the number of activated voxels between Sessions 1 and 2, independently of diazepam administration. These results indicate that diazepam may be administered for premedication prior to fMRI investigations.

  • 153.
    Rudner, Mary
    et al.
    Linköpings universitet, Institutionen för nervsystem och rörelseorgan. Linköpings universitet, Hälsouniversitetet.
    Cedefamn, Jonny
    Friman, Ola
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Knutsson, Hans
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Lundberg, Peter
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Söderfeldt, Birgitta
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för nervsystem och rörelseorgan. Östergötlands Läns Landsting, Närsjukvården i centrala Östergötland, Neurologiska kliniken.
    Are levels of language processing reflected in neural activation? - An fMRI study.2001Ingår i: NeuroImage, ISSN 1053-8119, E-ISSN 1095-9572, Vol. 13, nr 6Artikel i tidskrift (Refereegranskat)
  • 154.
    Rydell, Joakim
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Borga, Magnus
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Lundberg, Peter
    Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiofysik. Linköpings universitet, Tekniska högskolan. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Knutsson, Hans
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Dimensionality and degrees of freedom in fMRI data analysis - a comparative study2004Ingår i: Biomedical Imaging: Nano to Macro, 2004. IEEE International Symposium on, IEEE , 2004, s. 988-991 vol.1Konferensbidrag (Refereegranskat)
    Abstract [en]

    Two- and three-dimensional isotropic and anisotropic spatial filters for adaptive fMRI data analysis are compared in terms of activation detection sensitivity and specificity. Evaluations using both real and artificial data are presented. It is shown that three-dimensional anisotropic filters provide superior activation detection performance.

  • 155.
    Rydell, Joakim
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Borga, Magnus
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Lundberg, Peter
    Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Knutsson, Hans
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Dimensionality and number of parameters in adaptive filtering of fMRI data2004Ingår i: Proceedings of the Swedish Symposium on Image Analysis (2004), 2004, s. 90-93Konferensbidrag (Övrigt vetenskapligt)
  • 156.
    Rydell, Joakim
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Johansson, Andreas
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    Leinard, Olof Dahlqvist
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Hälsouniversitetet.
    Knutsson, Hans
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Hälsouniversitetet.
    Farnebäck, Gunnar
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska högskolan.
    Lundberg, Peter
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiologi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen. Östergötlands Läns Landsting, Bildmedicinskt centrum, Röntgenkliniken i Linköping.
    Borga, Magnus
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Hälsouniversitetet.
    Three Dimensional Phase Sensitive Reconstruction for Water/Fat Separation in MR Imaging using Inverse Gradient2008Ingår i: Proceedings of the International Society for Magnetic Resonance in Medicine annual meeting (ISMRM'08), 2008, s. 1519-Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Three dimensional phase sensitive reconstruction on two point Dixon volumes has been implemented with use of the inverse gradient. The results has beencompared with the inverse gradient method in two dimensions as well as with the well established region growing method proposed by Ma. The inversegradient method in 3D is able to unwrap the phase field in uncertain regions where the region growing method and the inverse gradient method in 2D cometo a stop.

  • 157.
    Rydell, Joakim
    et al.
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan.
    Knutsson, Hans
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan.
    Pettersson, Johanna
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan.
    Johansson, Andreas
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska högskolan.
    Farnebäck, Gunnar
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska högskolan.
    Dahlqvist Leinhard, Olof
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    Lundberg, Peter
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiofysik. Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiologi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Bildmedicinskt centrum, Röntgenkliniken i Linköping. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Nyström, Fredrik
    Linköpings universitet, Institutionen för medicin och hälsa, Internmedicin. Linköpings universitet, Hälsouniversitetet.
    Borga, Magnus
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan.
    Phase Sensitive Reconstruction for Water/Fat Separation in MR Imaging Using Inverse Gradient2007Ingår i: Medical Image Computing and Computer-Assisted Intervention – MICCAI 2007. 10th International Conference, Brisbane, Australia, October 29 - November 2, 2007, Proceedings, Part I / [ed] Nicholas Ayache, Sebastien Ourselin and Anthony Maeder, Springer Berlin/Heidelberg, 2007, s. 210-218Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents a novel method for phase unwrapping for phase sensitive reconstruction in MR imaging. The unwrapped phase is obtained by integrating the phase gradient by solving a Poisson equation. An efficient solver, which has been made publicly available, is used to solve the equation. The proposed method is demonstrated on a fat quantification MRI task that is a part of a prospective study of fat accumulation. The method is compared to a phase unwrapping method based on region growing. Results indicate that the proposed method provides more robust unwrapping. Unlike region growing methods, the proposed method is also straight-forward to implement in 3D.

  • 158.
    Salerud, Göran
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Gunnarsson, S.
    Lund, Eva
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Problem Based Learning (PBL) and cirricula redesign in BioMedical Engineering (BME) in the framework of Concieve Design Implement and Operate (CDIO) initiative2005Ingår i: Biomedical Engineering Educational Summit meeting,2005, 2005Konferensbidrag (Övrigt vetenskapligt)
  • 159.
    Salerud, Göran
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Lund, Eva
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Multiprofessional education in Biomedical Engineering using PBL2000Ingår i: Int Academy Medical and Biological Engineering. Workshop on Biomedical Engineering Education.,2000, 2000Konferensbidrag (Övrigt vetenskapligt)
  • 160.
    Salerud, Göran
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Lund, Eva
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Multiprofessional education in Biomedical Engineering with individual learning documents for students evaluation and assessment2000Ingår i: Biomedical Engineering Educational Summit meeting,,2000, 2000Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

      

  • 161.
    Salih, Isam
    et al.
    Linköpings universitet, Institutionen för medicin och vård.
    Bäckström, Mattias
    Man-Technology-Environment Research Centre, Örebro University, Örebro, Sweden.
    Karlsson, Stefan
    Lund, Eva
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    Pettersson, Håkan
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Impact of fluoride and other aquatic parameters on radon concentration in natural waters2004Ingår i: Journal of Applied Radiation & Isotopes, ISSN 0969-8043, Vol. 60, nr 1, s. 99-104Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Radon (222Rn) accumulation in water in relation to stable elements was studied for the purpose of determining factors influencing the transfer of 222Rn to and from water. In 72 groundwater samples, 222Rn and about 70 analytical parameters were analysed using radiometric and ICP-MS techniques. Using multivariate statistics (partial least squares), it was observed that 222Rn has a positive correlation with fluoride and uranium. The correlation with fluoride was further investigated by a laboratory time-scale experiment to measure the emanation of 222Rn from water as a function of fluoride, pH and carbonate. The transfer of 222Rn from water was measured by continuous monitoring in air in a closed loop set-up. It was observed that fluoride in water adhere or trap 222Rn preferably in acidic water (pH 3). It is suspected that natural physical processes (such as diffusion and microbubble phenomenon) are less effective to transport 222Rn in the presence of fluoride.

  • 162.
    Salih, Isam
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    Pettersson, Håkan
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Lund, Eva
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    Determination of 222Rn and 226Ra in water using a large volume ionisation chamber2000Ingår i: Journal of Environmental Radioactivity, ISSN 0265-931X, Vol. 48, nr 2, s. 235-245Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A new method for measuring 222Rn and 226Ra in water has been devised. It is based on exhaling radon to a void volume by continuous bubbling of air through the water. The exhaled radon is then transferred in a closed circuit to a modified radon gas pulse ionisation chamber for alpha-spectrometric measurements. About 86% of the radon in water is transferred from 0.75 l of water to the void volume (3.2 l). The set-up offers direct and specific 222Rn measurements for a wide range of concentrations and shows a low detection limit (LLD=45 mBq l−1 for 8 h counting time). Radium in water is measured, via radon, after sample storage for a month. The method was compared with gamma ray spectrometry for radon and for radium, the latter after pre-concentration by co-precipitation with MnO2 from 10 l water samples. An excellent agreement between the two techniques was obtained. As a part of a radon survey, the method was employed for analysis of drinking water from bedrock wells.

  • 163.
    Salih, Isam
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    Pettersson, Håkan
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Lund, Eva
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    Uranium and thorium series radionuclides in drinking water from drilled bedrock wells: correlation to geology and bedrock radioactivity and dose estimation2002Ingår i: Radiation protection dosimetry, ISSN 0144-8420, Vol. 102, nr 3, s. 249-258Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Natural radioactivity in drinking water from 328 drilled wells was studied in correlation to source parameters. Poor correlation to both aquifer geology and bedrock radioactivity was observed. Concentrations of 238U, 226Ra, 228Ra, 222Rn and 210Po in groundwater samples was in the ranges <0.027-5.3, <0.016-4.9, <0.014-1.24, 5-8105 and <0.05-0.947 Bq.l(-1) respectively. In about 80% of the sites the radon concentration exceeds the Nordic recommended exemption level for radon in drinking water and 15% of the sites exceed the action limit. The effective doses from ingestion were calculated and presented in association with geology. Doses due to ingestion ranged between 0.05 and 20.4 mSv.y(-1), where the average contribution from 222Rn amounted to 75%. In comparison, the effective doses from inhalation of indoor 222Rn ranged between 0.2 and 20 mSv.y(-1). The average contribution from inhalation of 222Rn in air to the total effective dose (ingestion+inhalation) was 58 +/- 22%, 73 +/- 18% and 77 +/- 16% (1 SD) for the age categories 1 y, 10 y and adults respectively.

  • 164.
    Salih, Isam
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    Pettersson, Håkan
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Sivertun, Åke
    Linköpings universitet, Institutionen för datavetenskap, GIS - Geografiska informationssystem. Linköpings universitet, Tekniska högskolan.
    Lund, Eva
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    Spatial correlation between radon (222Rn) in groundwater and bedrock uranium (238U): GIS and geostatistical analyses2002Ingår i: Journal of Spatial Hydrology, ISSN 1530-4736, Vol. 2, nr 2, s. 1-10Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study describes approaches to create surface maps of radon in groundwater based on measurements of radon (222Rn) in drilled bedrock wells at unevenly distributed sites and uranium bedrock maps from the South East of Sweden, the Östergotland county (N 58°14’ – N 58°56’and E 14°53’ – E 16°06’), see figure 1. Geostatistical techniques of inverse distance weighted(IDW), kriging and cokriging were compared in terms of their interpolation power and correlation between the produced radon in the water layer and the bedrock uranium layer. The goal of these analyses and calculations is to improve our understanding concerning the factors influencing the transport of radon. Therefore, these interpolation techniques were investigated by optimizing parameters that are used in the specific interpolation. Using the IDW interpolator method at fixed radius enabled us to determine the linkage or search distances for auto correlation, and linkage between radon in water and bedrock. This method showed good agreement with the cokriging method when using uranium concentration as a secondary variable. Good interpolation layers (with least root mean square errors RMSE=232) were obtained by kriging. However, the kriged radon surface showed poor correlation with bedrock uranium layers. The best radon in waterlayer that match with uranium in bedrock layer was produced using IDW interpolator (RMSE=377, using all points). The correlation coefficient (R2) is 0.5 while for the kriging method the best correlation is R2 = 0.1. A compromise between the two approaches is demonstrated.

  • 165.
    Sandborg, Michael
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen. Linköpings universitet, Hälsouniversitetet.
    Bildkvalitet vid projektionsradiografi2008Ingår i: Radiologi / [ed] Peter Aspelin, Holger Pettersson, lund: Studentlitteratur , 2008, 1, s. 35-49Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [sv]

    Radiologin är en av de kliniska specialiteter som växer snabbast och idag omfattar den klassisk röntgen, datortomografi, magnetkamera, nuklearmedicin, positronemissionstomografi och ultraljud. Den tekniska utvecklingen har inneburit att vi förutom att avbilda olika organs morfologi och funktion också kan avbilda skeenden på cellulär, molekylär och atomnivå och ersätta tvådimensionella bilder med tredimensionella och virtuella bilder. Radiologin kommer att spela en stor roll för den molekylära förståelsen av uppkomstmekanismen bakom sjukdomar. Den snabba digitala utvecklingen förenklar att kommunicera bilder och detta har gjort radiologin tillgänglig inte bara för radiologer utan även för ett stort antal medarbetare i vården. Denna lärobok vänder sig främst till medicine kandidater och läkare, men genom sin utformning, bl.a. det stora antalet bilder med kommentarer, kan den också användas av andra yrkeskategorier som är under utbildning eller verksamma inom sjukvården. Varje kapitel har skrivits av författare som utsetts av respektive subspecialitetsförening till Svensk Förening för Medicinsk Radiologi. Föreningen har subventionerat produktionen av boken så att så många som möjligt inom sjukvården ska ha möjlighet att införskaffa den. Till boken finns en omfattande webbplats med bokens röntgenmaterial som gjorts sökbart för läsaren. För att få tillgång till materialet krävs en aktiveringskod. I varje bok finns en unik kod som efter aktivering är förbrukad. För att säkerställa att du som köpare får denna kod, är boken inplastad. Webbplatsen blir klar sista veckan i augusti.

  • 166.
    Sandborg, Michael
    Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Bildkvalitet vid projektionsradiografi2004Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    En bild av god klinisk kvalitet har egenskaper som möjliggör att diagnostiskt viktiga detaljer och strukturer kan observeras av radiologen med tillräckligt stor säkerhet. Kvalitetsbegreppet bör relateras till hur väl (dvs. med vilken säkerhet) bilden ger svar på frågeställningen i remissen, eller hur väl bilden tillsammans med radiologens kunskap och erfarenhet löser uppgiften. Målet är att

    • att åstadkomma tillräckligt bra bilder för säker diagnostik,
    • att bildkvaliteten är reproducerbar och
    • att patienten utsätts för ett minimum av stråldos och andra undersökningsrelaterade biverkningar.

    För att säkerställa detta krävs mätningar av bildkvaliteten. Mätning av klinisk bildkvalitet kan omfatta en studie av en eller flera radiologers observationer eller bedömningar av bilderna som ett diagnostiskt redskap. Med fysikalisk bildkvalitet menas här objektiva mätningar av olika egenskaper i bilderna eller i bilddata som är relaterade till den kliniska bildkvaliteten.

    Ladda ner fulltext (pdf)
    Bildkvalitet vid projektionsradiografi
  • 167.
    Sandborg, Michael
    Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Calculation and analysis of DQE for some image detectors in mammography1998Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The development and clinical testing of digital detector designs for mammography are making rapid progress and there is widespread interest in comparing the performance of these new detectors to that of analogue screen-film mammography systems. In this report, Monte Carlo calculations of the x-ray absorption characteristics (single-event distribution), the quantum absorption, Aq, and detective quantum, DQEq, efficiencies are made and compared to results from the literature. Detectors of CsI and Si of various thicknesses are compared to a state-ofthe art analogue, screen-film system (Gd2O2S) in the energy range 1-35 keV. The results show that 1.5 mm thick Si detectors will have the same DQEq as commonly used Gd2O2S fluorescent screens and that a CsI phosphor of 80 mm has similar DQEq as 1.0 mm Si. The total DQE (including added noise and inherent detector unsharpness) of fluorescent screen-film systems will be significantly reduced from this value due to the light scatter, film noise and the inherent limitations caused by the film characteristic curve. This indicates that also thinner Si detectors (0.3-0.5 mm), which do not suffer from these limitations but from a comparably low Aq may have a total performance DQE(f) comparable to that of traditional screen-film based, image detectors.

    Ladda ner fulltext (pdf)
    Calculation and analysis of DQE for some image detectors in mammography
  • 168.
    Sandborg, Michael
    Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Computed Tomography: Physical principles and biohazards1995Rapport (Övrigt vetenskapligt)
    Abstract [en]

    In planar projected images of the patient, important details may be hidden by over-laying tissues. By using slice-imaging techniques (tomography), selective demonstration of morphologic properties, layer by layer, may be performed.

    Computerised tomography, CT, is an ideal form of tomography yielding sequence images of thin consecutive slices of the patient and providing the opportunity to localise in three dimensions. Unlike conventional, classical tomography, computerised tomography does not suffer from interference from structures in the patient outside the slice being imaged. This is achieved by irradiating only thin slices of the patient with a fan-shaped beam. Transaxial images (tomograms) of the patient’s anatomy can give more selective information than conventional planar projection radiographs. Compared to planar radiography, CT images have superior contrast resolution, i.e., they are capable of distinguishing very small differences in tissue-attenuation (contrasts), but have inferior spatial resolution. An attenuation difference of 0.4% can be visualised but the smallest details in the image that can be resolved must be separated at least 0.5 mm. In conventional planar radiography, the lowest detectable contrast is larger but details of smaller size can be separated.

    Ladda ner fulltext (pdf)
    Computed Tomography : Physical principles and biohazards
  • 169.
    Sandborg, Michael
    et al.
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Abramowicz, JS
    Lewis, V
    Plain Radiography and Fluoroscopy1999Ingår i: Gynecological Imaging, London: Elsevier Health Sciences , 1999, s. 19-30Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 170.
    Sandborg, Michael
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen. Linköpings universitet, Hälsouniversitetet.
    Alm Carlsson, Gudrun
    Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    Influence on X-ray energy spectrum, contrasting detail and detector on the signal-to-noise ratio (SNR) and detective quantum efficiency (DQE) in projection radiography1992Ingår i: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 7, nr 6, s. 1245-1263Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A lower limit to patient irradiation in diagnostic radiology is set by the fundamental stochastics of the energy imparted to the image receptor (quantum noise). Image quality is investigated and expressed in terms of the signal-to-noise ratio due to quantum noise. The Monte Carlo method is used to calculate signal-to-noise ratios (SNRDelta S) and detective quantum efficiencies (DQEDelta S) in imaging thin contrasting details of air, fat, bone and iodine within a water phantom using X-ray spectra (40-140 kV) and detectors of CsI, BaFCl and Gd2O2S. The atomic composition of the contrasting detail influences considerably the values of SNRDelta S due to the different modulations of the energy spectra of primary photons passing beside and through the contrasting detail. By matching the absorption edges of the contrasting detail and the detector, a partially absorbing detector may be more efficient (yield higher SNRDelta S) than a totally absorbing one; this is demonstrated for the case of detecting an iodine detail using a CsI detector. The degradation of SNRDelta S and DQEDelta S due to scatter is larger when the detector is operated in the photon counting compared to in the energy integrating mode and for partially absorbing compared to totally absorbing detectors.

  • 171.
    Sandborg, Michael
    et al.
    Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Alm Carlsson, Gudrun
    Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Jämförelse mellan ett niobfilter (NIOBI-X) och konventionell filtrering vid skärmfilm radiografi: Inverkan på primärspektrum, kontrast, rörbelastning och strålrisk1990Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Optimering av information till strålrisk inom diagnostisk radiologi innebär att finna den.metod att framställa en bild, innehållande den nödvändiga informationen (bildkvaliteten), som ger lägsta strålrisk för patienten. Valet av fotonenergispektrum är en betydelsefull parameter vid optimeringen. Olika energispektrum kan erhållas då man varierar rörspänningen, tilläggsfiltermaterial och filtertjocklek. Av de fundamentala bildkvalitetsparamerarna kontrast, skärpa och brus är, vid konventionell skärm-film radiografi, kontrast och skärpa de viktigaste. De påverkas båda, men framförallt kontrasten, av energispektrum, dvs. rörspänningen och tilläggsfiltrets material och tjocklek.

    Ladda ner fulltext (pdf)
    Jämförelse mellan ett niobfilter (NIOBI-X) och konventionell filtrering vid skärmfilm radiografi : Inverkan på primärspektrum, kontrast, rörbelastning och strålrisk
  • 172.
    Sandborg, Michael
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen. Linköpings universitet, Hälsouniversitetet.
    Alm Carlsson, Gudrun
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    Persliden, Jan
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    Dance, David
    n/a.
    Comparison of different materials for test phantoms in diagnostic radiology1993Ingår i: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 49, nr 1, s. 345-347Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The use of test phantoms in diagnostic radiology is a well established practice in image quality control. Here Monte Carlo methods are used for comparing different phantom materials (water, Lucite, polystyrene, paraffin wax, Mylar, Mix-D, M3, Alderson muscle B and A-150) relative to soft tissue with regard to different physical quantities such as contrast and mean absorbed dose in the phantom. The results for each material are derived as the equivalent thicknesses resulting in the same value of the quantity of interest as a soft tissue phantom of a given thickness, this being varied between 5 and 25 cm. The phantom material yielding the smallest spread of equivalent thicknesses is regarded as the most soft tissue equivalent one. Water, Mix-D and M3 are the materials most equivalent to soft tissue of the phantom materials tested. Paraffin wax, polystyrene and Lucite show a larger spread in equivalent thicknesses.

  • 173.
    Sandborg, Michael
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen. Linköpings universitet, Hälsouniversitetet.
    Carlsson, C. A.
    Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    Alm Carlsson, Gudrun
    Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    Shaping X-ray spectra with filters in X-ray diagnostics1994Ingår i: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 32, nr 4, s. 384-390Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The influence on image contrast, tube load and patient mean absorbed dose of different ways of shaping diagnostic X-ray spectra by placing filters in the beam is derived for two radiographic models (abdominal screen-film radiography and intra-oral, dental radiography) using a computational model. The filters are compared at either equal tube load (keeping tube potential constant) or equal contrast (adjusting the tube potential with the different filters), but always at equal energy imparted per unit area to the image receptor. Compared at equal tube load and relative to standard aluminium filtration, reductions in the mean absorbed dose in the patient of 15–25% can be achieved using filters of Cu, Ti, W and Au (increasing the tube load by 30–40% compared with standard aluminium filtration). However, contrast is also reduced by 7%. Compared at equal contrast, the dose reductions are smaller, about 10%. Filters of copper are generally recommended, as are filters of aluminium. The use of bandpass filters (K-edge filters) should be restricted to examinations where the need for substantial variation in tube potential from patient to patient is small. The benefit of using thicker filters than those commonly used today (increasing tube load by factors of 1.4–2.0 compared with no added filter) is small as the dose reduction is most rapid for small initial values of added filters, and the increase in tube load increases steadily with increasing filter thickness.

  • 174.
    Sandborg, Michael
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen. Linköpings universitet, Hälsouniversitetet.
    Christoffersson, Jan-Ove
    n/a.
    Alm Carlsson, Gudrun
    Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    Almen, Torsten
    n/a.
    Dunce, D A
    n/a.
    The physical performance of different x-ray contrast agents: calculations using a Monte Carlo model of the imaging chain1995Ingår i: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 40, nr 7, s. 1209-1224Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A Monte Carlo computational model of the imaging chain has been used to investigate the performance of X-ray contrast agents with atomic number, Z, 53<or=Z<or=90 with respect to physical image quality descriptors (contrast and signal to noise ratio, SNR) and patient mean absorbed dose. Contrast agents of equal molar concentrations were used within a water slab (simulating the patient). The imaging conditions were chosen to represent adult and paediatric examinations. For all tube potentials studied (40-140 kV), the contrast agents with the highest atomic numbers (bismuth and thorium) gave the highest contrast. In analogue screen-film imaging, several other contrast agents could produce a higher image contrast than iodine in a limited range of tube potentials. This advantage could alternatively be effected as a reduced amount of administered contrast agent, or as a reduced mean absorbed dose in the patient. In digital imaging, a lower mean absorbed dose for a constant SNR than that with iodine can be achieved for ranges of tube potentials and contrast agents. Bismuth and thorium yield a lower dose than iodine at all studied tube potentials. Gadolinium and erbium could alternatively be used at a broad range of tube potentials above 90 kV with a dose penalty of only 5-20%.

  • 175.
    Sandborg, Michael
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen. Linköpings universitet, Hälsouniversitetet.
    Dance, David
    n/a.
    Alm Carlsson, Gudrun
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Hälsouniversitetet.
    Persliden, Jan
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    Monte Carlo study of grid performance in diagnostic radiology: factors which affect the selection of tube potential and grid ratio1993Ingår i: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 66, s. 1164-1176Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A Monte Carlo computational model has been developed for the study of the performance of anti-scatter grids in diagnostic radiology. It is used here to estimate the scatter in the image plane from soft tissue phantoms (representing the patient) and to calculate image contrast and the mean absorbed dose in the phantom. Different scattering conditions, representative of various examinations, have been investigated: adult lumbar spine; small field radiography and fluoroscopy; adult chest and paediatric pelvis and chest. For each scattering condition, the combinations of tube potential and grid ratio have been found which, for a well designed grid, result in the lowest mean absorbed dose in the phantom for a fixed contrast level. In examinations which generate large amounts of scatter, the use of high grid ratios in combination with high tube potentials is favourable with regard to both mean absorbed dose in the phantom and tube charge. When less scatter is generated, either the grid ratio or the tube potential can be varied to achieve the desired contrast level. High grid ratios require shorter exposure times, but need careful alignment in the beam to prevent primary radiation cut-off. It is shown that the air gap technique can be used to reduce patient dose in examinations with small amounts of scatter, but in combinations with a lower tube potential than when a grid is used.

  • 176.
    Sandborg, Michael
    et al.
    Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiofysik. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen. Linköpings universitet, Hälsouniversitetet.
    Dance, David
    The Royal Marsden Hospital.
    Alm Carlsson, Gudrun
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    Persliden, Jan
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    Monte Carlo study of grid performance in diagnostic radiology: task dependent opti­misation for screen-film imaging1994Ingår i: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 67, s. 76-85Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An optimization of anti-scatter grid design using Monte Carlo techniques in diagnostic radiology is presented. The criterion for optimization was to find the combinations of the grid parameters (lead strip width, grid ratio and strip density) and tube potential which result in the lowest mean absorbed dose in the patient at fixed image contrast. The optimization was performed in three irradiation geometries, representing different scattering conditions (paediatric examinations, and two adult lumbar spine examinations) and was restricted to grids using fibre materials in covers and interspaces. Grid designs currently available were studied, as were designs which use thinner strips (< 30 µm) and higher grid ratios (> 18). It was found that grids with widely different strip densities (strips cm–1) and grid ratios can have good performance provided that they are used with appropriate strip width and tube potential. With increasing amounts of scatter, the optimal grid requires thicker strips and higher grid ratios. Increasing the strip density and using thinner strips and higher grid ratios are generally required. Grids with low strip density (25 strips cm–1) were found to be less sensitive to alterations in strip width. Optimal grids for paediatric radiology require thinner strips (10–20 µm) than those in currently available grids. Grids on the market are best suited for examinations of the adult body in anteroposterior (AP) view. In the adult lateral view, representing the largest scattering volume, higher grid ratios (> 18) than those in existing grids would be optimal. Examples of good grid designs are given for each examination.

  • 177.
    Sandborg, Michael
    et al.
    Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiofysik. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen. Linköpings universitet, Hälsouniversitetet.
    Dance, David
    n/a.
    Alm Carlsson, Gudrun
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    Persliden, Jan
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    Results from an optimisation of grid design in diagnostic radiology1995Ingår i: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 57, nr 1, s. 211-215Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Results of an optimisation of grid design using a Monte Carlo model of the imaging chain are presented. Patient dose is significantly reduced by changing from aluminium to fibre grid covers and interspaces while keeping contrast constant. Numerous commercial grids have been investigated to identify superior designs. For optimal use, grids with high strip density require thinner lead strips and higher ratios than grids with low strip density. In paediatric radiology, grids with very thin strips (10-20 µm), or an air gap can be considered. In an adult lumbar spine examination, the optimal grid ratios are higher (greater than 15) than in commercial grids. This is particularly accentuated for grids with high strip density, fibre interspaces and in the lateral view. For a given imaging task, it is possible to identify grids of different design that have good performance, provided an appropriate strip width and tube potential are selected.

  • 178.
    Sandborg, Michael
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen. Linköpings universitet, Hälsouniversitetet.
    Dance, David
    n/a.
    Alm Carlsson, Gudrun
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen. Linköpings universitet, Hälsouniversitetet.
    Persliden, Jan
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    Selection of anti-scatter grids for different imaging tasks: the advantage of low atomic number cover and interspace materials1993Ingår i: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 66, s. 1151-1163Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A Monte Carlo computer program has been developed for the study of anti-scatter grids used in diagnostic radiology. The program estimates the scatter from soft tissue phantoms representative of either adult or paediatric examinations and uses dose increase, signal-to-noise ratio improvement and contrast improvement factors to study grid performance. It has been used to quantify the advantage of replacing grids with aluminium covers and interspaces by grids using materials of low atomic number for these components. Two approaches are used. First, the aluminium and low atomic number alternatives are compared for five grid ratios at fixed strip density and width and for tube potentials of 50, 70, 100 and 150 kV. Second, 44 commercially available grids are compared for three different imaging situations (lumbar spine, chest and paediatric). The results demonstrate that grids made with carbon fibre cover and cotton fibre interspace result in greater improvements in contrast and signal-to-noise ratio, and lower dose increase factors, than do grids made with aluminium. The dose reduction varies with irradiation conditions and is generally larger at lower tube potentials, higher grid ratios and lower strip densities. A typical reduction in mean absorbed dose in the patient is 30% in an adult lumbar spine (AP view) at 70 kV with a grid with 36 strips per centimetre and ratio 12.

  • 179.
    Sandborg, Michael
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen. Linköpings universitet, Hälsouniversitetet.
    Dance, David
    n/a.
    Alm Carlsson, Gudrun
    Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    Persliden, Jan
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    Tapiovaara, Markku
    n/a.
    A Monte Carlo study of grid performance in diagnostic radiology: task-dependent opti­mization for digital imaging 1994Ingår i: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 39, nr 10, s. 1659-1676Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A Monte Carlo computational model has been used to optimize grid design in digital radiography. The optimization strategy involved finding grid designs that, for a constant signal-to-noise ratio, resulted in the lowest mean absorbed dose in the patient. Different examinations were simulated to explore the dependence of the optimal scatter-rejection technique on the imaging situation. A large range of grid designs was studied, including grids with both aluminium and fibre interspaces and covers, and compared to a 20 cm air gap. The results show that the optimal tube potential in each examination does not depend strongly on the scatter-rejection technique. There is a significant dose reduction associated with the use of fibre-interspaced grids, particularly in paediatric radiography. The optimal grid ratio and strip width increase with increasing scattering volume. With increasing strip density, the optimal strip width decreases, and the optimal grid ratio increases. Optimal grid ratios are higher than those used today, particularly for grids with large strip density. It is, however, possible to identify grids of good performance for a range of strip densities and grid ratios provided the strip width is selected accordingly. The computational method has been validated by comparison with measurements with a caesium iodide image receptor.

  • 180.
    Sandborg, Michael
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen. Linköpings universitet, Hälsouniversitetet.
    Dance, David
    The Royal Marsden Hospital.
    Persliden, Jan
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    Alm Carlsson, Gudrun
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet.
    A Monte Carlo program for the calculation of contrast, noise and absorbed dose in diagnostic radiology1994Ingår i: Computer Methods and Programs in Biomedicine, ISSN 0169-2607, E-ISSN 1872-7565, Vol. 42, nr 3, s. 167-180Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A Monte Carlo computer program has been developed for the simulation of X-ray photon transport in diagnostic X-ray examinations. The simulation takes account of the incident photon energy spectrum and includes a phantom (representing the patient), an anti-scatter grid and an image receptor. The primary objective for developing the program was to study and optimise the design of anti-scatter grids. The program estimates image quality in terms of contrast and signal-to-noise ratio, and radiation risk in terms of mean absorbed dose in the patient. It therefore serves as a tool for the optimisation of the radiographic procedure. A description is given of the program and the variance-reduction techniques used. The computational method was validated by comparison with measurements and other Monte Carlo simulations.

  • 181.
    Sandborg, Michael
    et al.
    Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Dance, David R
    Department of Physics, The Royal Marsden NHS Trust, UK.
    Alm Carlsson, Gudrun
    Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Calculation of contrast and signal-to-noise degradation factors for digital detectors in chest and breast imaging2003Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The Monte Carlo model of an x-ray imaging system, used in the EU 5th framework project by the Linköping and London partner to study chest and breast imaging, was developed jointly by the London and Linköping partners. It incorporates a model of the x-ray imaging system (x-ray tube, filtration, anti-scatter device and image receptor etc.) and the patient by using a voxel phantom of an adult male. Validation and calibration experiments have been performed for both the chest (Ullman et al 2003b) and the breast model.

    The model allows inclusion of anatomical or pathological details at particular positions in the anatomy and is able to calculate measures of image quality such as contrast and signal-to-noise ratio and measures of radiation risk for example entrance air kerma and effective dose. It allows alteration of imaging system settings such as tube voltage, filtration, beam size and position, choice of anti-scatter device and choice of image detector etc. The model is a useful tool for optimisations since it has been shown that in chest and lumbar spine radiography is able to predict clinical image quality as assessed by a group of radiologists.

    In the Monte Carlo model (MC-model) the image quality measures are calculated assuming a perfectly sharp imaging system and correction factors need to be applied to the computed data in order to make the image quality measures agree on an absolute scale. The calculation of correction factors for contrast and signal-tonoises are described in this report. A similar report focusing on analogue screen-film chest and lumbar spine radiography was completed some years ago and some of the concepts and methods are similar.

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    Calculation of contrast and signal-to-noise degradation factors for digital detectors in chest and breast imaging
  • 182.
    Sandborg, Michael
    et al.
    Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Dance, David R
    Joint Department of Physics, The Royal Marsden NHS Trust, UK.
    Alm Carlsson, Gudrun
    Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Implementation of unsharpness and noise into the model of the imaging system: Applications to chest and lumbar spine screen-film radiography1999Rapport (Övrigt vetenskapligt)
    Abstract [en]

    A model of the complete x-ray imaging system including the patient is a powerful tool for imaging system analysis and the optimisation of image quality and patient dose. It allows flexible variation of the system components (i.e. x-ray source, antiscatter device and image detector) and study of their effect on image quality and patient risk. Our group has developed, validated and calibrated a Monte Carlo model of the complete imaging system for chest and lumbar spine examination including voxalised human male anatomy. The Monte Carlo program calculates the contrast and signal-to-noise ratio (SNR) of various contrasting details within the voxel phantom. Important details in the images have been selected by consulting radiologist and the EU document of image quality criteria. The entrance surface dose without back-scatter and the effective dose are used as measures of patient radiation risk.

    The contrasts of the details are derived initially from Monte Carlo estimates of the energy imparted per unit area to the image detector beside and behind the detail. However, this ignores the effects of unsharpness in the imaging chain (such as screen-film, geometric and motion unsharpness) and the influence on contrast of the film characteristic curve. In the Monte Carlo program, SNR is calculated assuming that the noise arises from the random fluctuations in the energy imparted per unit area to the image detector only. However, other noise sources also contribute to the total noise, such as screen and film noise. Hence the model of the imaging system needs to be further developed to take these effects into account. The methods used to extend the model are described below together with illustrations of their effect on the difference in optical density, DOD, and SNR in chest and lumbar spine imaging.

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    Implementation of unsharpness and noise into the model of the imaging system : Applications to chest and lumbar spine screen-film radiography
  • 183.
    Sandborg, Michael
    et al.
    Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Dance, David R.
    Department of Medical Physics, The Royal Marsden Hospital, Fulham Road, SW3 6JJ London, United Kingdom.
    Alm Carlsson, Gudrun
    Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Persliden, Jan
    Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    The choice of anti-scatter grids in diagnostic radiology: the optimization of image quality and absorbed dose1993Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    A Monte Carlo model is developed to study and optimise the design of antiscatter grids in diagnostic radiology. The imaging chain including X-ray energy spectra, phantom (representing the patient), grid and image receptor is simulated. Image quality is quantified in terms of contrast (conventionai screen-film imaging) and signal-to-noise ratio, SNR (digital imaging) and the radiation detriment to the patient (risk) by the mean absorbed dose in the phantom. The advantages of using fibre instead of aluminium for grid interspaces and covers are quantified. Compared to aluminium grids, the absorbed dose is reduced by 10-50%, contrast is improved by 0-10% and SNR by 10-40% (digital radiography). The advantages are larger at low tube potentials and for grids with high ratio and low strip density. Commercial grids, with different interspace materials, strip density, strip width and grid ratio, are compared in paediatric, lumbar spine and chest examinations. The differences in dose increase and contrast improvement factors obtained with these grids are mainly due to the use of different materials in the grid interspaces, but the strip design is also important. In a global optimisation of grid design and tube potential at fixed contrast, it is found that grids of different strip density and ratio all can have good performances provided that they are used with appropriate strip width and tube potential. In the paediatric examination, low ratio grids need thinner strips than used today to be optimal. A small air gap could alternatively be used. In examinations with more scatter (adult AP), present commercial grids are optimal (r=12-16, d=30-50µm). In the lateral view (even more scatter), grids with ratios larger than 16 are optimal provided the grid can be accurately aligned in the beam. The optimization is performed with grids with fibre interspaces and covers since low atomic number materials should preferably be used for materials between the patient and the receptor. Optimal grids with aluminium for these components have lower grid ratio and higher strip densities than optimal fibre grids.

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    The choice of anti-scatter grids in diagnostic radiology : the optimization of image quality and absorbed dose
  • 184.
    Sandborg, Michael
    et al.
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Fransson, Sven Göran
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård. Östergötlands Läns Landsting, Hjärtcentrum, Kardiologiska kliniken.
    Pettersson, Håkan
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Evaluation of patient-absorbed doses during coronary angiography and intervention by femoral and radial artery access2004Ingår i: European Radiology, ISSN 0938-7994, E-ISSN 1432-1084, Vol. 14, nr 4, s. 653-658Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim of this study was to compare the radiation dose to patients during coronary angiography (CA) and coronary intervention (percutaneous transluminal coronary angioplasty, PTCA) by the femoral or radial artery access routes. A plane-parallel ionisation chamber, mounted on an under-couch X-ray tube (Siemens Coroskop TOP with an optional dose reduction system), recorded the dose-area product (DAP) to the patient from 40 coronary angiographies and 42 coronary interventions by the femoral route. The corresponding numbers for radial access were 36 and 24, respectively. Using a human-shaped phantom, conversion factors between maximum entrance surface dose and DAP were derived for CA and CA plus PTCA, respectively. The dose to the staff was measured with TL dosimeters for 22 examinations. Fluoroscopy time and DAP were significantly (p=0.003) larger using the radial access route for coronary angiography (7.5 min, 51 Gy cm2) than the corresponding values obtained from femoral access route (4.6 min, 38 Gy cm2. For CA plus PTCA the fluoroscopy time and DAP were larger for radial access (18.4 min, 75 Gy cm2) than for femoral access (12.5 min, 47 Gy cm2, p=0.013). In our experience, radial access did significantly prolong the fluoroscopy time and increase the patient doses.

  • 185.
    Sandborg, Michael
    et al.
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Langer, JE
    Computed tomography: physical principles and imaging techniques1999Ingår i: Gynecological Imaging, London: Elsevier Health Sciences , 1999, s. 31-46Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 186.
    Sandborg, Michael
    et al.
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Mc Vey, Graham
    Dance, David
    Alm Carlsson, Gudrun
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Schemes for the optimization of chest radiography using a computer model of the patient and x-ray imaging system2001Ingår i: Medical physics (Lancaster), ISSN 0094-2405, Vol. 28, nr 10, s. 2007-2019Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A computer program has been developed to model chest radiography. It incorporates a voxel phantom of an adult and includes antiscatter grid, radiographic screen, and film. Image quality is quantified by calculating the contrast (?OD) and the ideal observer signal-to-noise ratio (SNRI) for a number of relevant anatomical details at various positions in the anatomy. Detector noise and system unsharpness are modeled and their influence on image quality is considered. A measure of useful dynamic range is computed and defined as the fraction of the image that is reproduced at an optical density such that the film gradient exceeds a preset value. The effective dose is used as a measure of the radiation risk for the patient. A novel approach to patient dose and image quality optimization has been developed and implemented. It is based on a reference system acknowledged to yield acceptable image quality in a clinical trial. Two optimizations schemes have been studied, the first including the contrast of vessels as measure of image quality and the second scheme using also the signal-to-noise ratio of calcifications. Both schemes make use of our measure of useful dynamic range as a key quantity. A large variety of imaging conditions was simulated by varying the tube voltage, antiscatter device, screen-film system, and maximum optical density in the computed image. It was found that the optical density is crucial in screen-film chest radiography. Significant dose savings (30%-50%) can be accomplished without sacrificing image quality by using low-atomic-number grids with a low grid ratio or an air gap and more sensitive screen-film system. Dose-efficient configurations proposed by the model agree well with the example of good radiographic technique suggested by the European Commission. ⌐ 2001 American Association of Physicists in Medicine.

  • 187.
    Sandborg, Michael
    et al.
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Radiofysik.
    McVey, G
    Dance, DR
    Alm Carlsson, Gudrun
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Verdun, FR
    Optimization of chest and lumbar spine radiography by Monte Carlo modelling of the patinet and imaging systems.1999Ingår i: SPIE Proc,1999, 1999, s. 444-454Konferensbidrag (Refereegranskat)
  • 188.
    Sandborg, Michael
    et al.
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    McVey, Graham
    Dance, David
    Alm Carlsson, Gudrun
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Comparison of model predictions of image quality with results of clinical trials in chest and lumbar spine screen-film imaging2000Ingår i: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 90, nr 1-2, s. 173-176Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The ability to predict image quality from known physical and technical parameters is a prerequisite for making successful dose optimisation. In this study, imaging systems have been simulated using a Monte Carlo model of the imaging systems. The model includes a voxelised human anatomy and quantifies image quality in terms of contrast and signal-to-noise ratio for 5-6 anatomical details included in the anatomy. The imaging systems used in clinical trials were simulated and the ranking of the systems by the model and radiologists compared. The model and the results of the trial for chest PA both show that using a high maximum optical density was significantly better than using a low one. The model predicts that a good system is characterised by a large dynamic range and a high contrast of the blood vessels in the retrocardiac area. The ranking by the radiologists and the model agreed for the lumbar spine AP.

  • 189.
    Sandborg, Michael
    et al.
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    McVey, Graham
    Dance, David
    Persliden, Jan
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Radiofysik.
    Alm Carlsson, Gudrun
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    A voxel phantom based Monte Carlo computer program for optimisation of chest and lumbar spine X ray imaging systems2000Ingår i: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 90, nr 1-2, s. 105-108Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A Monte Carlo computer model of X ray imaging systems has been developed which uses a voxel phantom to simulate the patient. Image details were selected in accordance with the European quality criteria document. Contrast and signal-to-noise ratio for these details were calculated to estimate image quality. Effective dose was computed to enable optimisation. The program was validated with measurements on phantoms, patients and digitised patient images. It was demonstrated that the computational model of the imaging system provides predictions of entrance dose and contrast that lie within the range of values measured on patients. To illustrate the importance of using a realistic model of the patient, scatter-to-primary ratios, S/P, in a chest PA examination were calculated. It was found that the S/P varied by a factor of 10 in the image and that a grid was slightly more efficient than an air gap in removing the scatter behind the heart.

  • 190.
    Sandborg, Michael
    et al.
    Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    McVey, Graham
    Joint Department of Physics, The Royal Marsden NHS Trust and Institute of Cancer Research, London, UK.
    Dance, David R
    Joint Department of Physics, The Royal Marsden NHS Trust, UK.
    Alm Carlsson, Gudrun
    Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Report on the study and optimisation of chestand lumbar spine X-ray imaging2000Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The optimisation of radiological equipment and equipment parameters is a key stage in the optimisation of image quality and patient dose in diagnostic radiology. It is essential, however, to underpin such optimisation with theoretical modelling which can provide both the direct quantification of the effect on image quality and dose of changes in system parameters and the opportunity for optimisation of equipment selection and use.

    Our principal contribution to the joint CEC-project 'Predictivity and Optimisation in Diagnostic Radiology' is in modelling of planar chest and lumbar spine radiographic examinations. The results of this work for the chest PA, lumbar spine AP and lumbar spine lateral examinations are presented in this report. Prior to this, several development stages have been completed which include the calibration and validation of our methods by measurements in the clinical environment on patients and patient images. These important aspects are not dealt with in detail here, but are described in separate reports. This report focuses on three aspects from our results of using our Monte Carlo model of the patient and imaging equipment:

    1. (1) Study of the effects on image quality and patient dose when the imaging parameters are varied;
    2. Establishment of imaging parameters and systems that result in as least as good image quality as systems with good performance singled out from results of clinical trials (optimisations);
    3. Comparison of the results from the model with the results from clinical trials performed by partners in the joint CEC-project.

    An objective of the report is to present our results at a level of detail not usually possible in the refereed scientific literature. The report should therefore not be read all at once, but preferably used as a ‘reference library’ or documentation of all our efforts. There are many interesting results and findings from this collaborative work and these will be submitted for publication to the appropriate journals.

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    Report on the study and optimisation of chestand lumbar spine X-ray imaging
  • 191.
    Sandborg, Michael
    et al.
    Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    McVey, Graham
    Department of Physics, The Royal Marsden NHS Trust, UK.
    Dance, David R
    Department of Physics, The Royal Marsden NHS Trust, UK.
    Alm Carlsson, Gudrun
    Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Persliden, Jan
    Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Collection and analysis of patient and image data for calibration of a voxelphantombased Monte Carlo code and for the modelling of important structures1997Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The contribution of the Medical Physics Departments at Linköping University (LKP) and The Royal Marsden NHS Trust (RMH) to the joint project ‘Predictivity and Optimisation in Medical Radiation Protection’ is in modelling of the chest and lumbar spine radiographic examinations. This involves:

    1. the development of quantitative imaging requirements;
    2. an investigation of the effect of imaging technique on image quality and patientdose, and
    3. an optimisation of system design.

    One of the objectives for this first reporting period (0-12 months) was to collect a set of chest and lumbar spine radiographs of patients for subsequent analysis in order to establish patient doses and important features in the images. The set of radiographs and the outcome of the image feature analysis will during this project’s second year be used to calibrate our Monte Carlo computational model of the conventional chest and lumbar spine screen-film X-ray imaging systems.

    Ladda ner fulltext (pdf)
    Collection and analysis of patient and image data for calibration of a voxelphantombased Monte Carlo code and for the modelling of important structures
  • 192.
    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, SWEDEN2010Ingår i: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 139, nr 1-3, s. 410-417Artikel i tidskrift (Refereegranskat)
    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.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 193.
    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, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Rossitti, Sandro
    Linköpings universitet, Institutionen för klinisk och experimentell medicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Neurokirurgiska kliniken US.
    Pettersson, Håkan
    Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Local skin and eye lens equivalent odses in interventional neuroradiology2010Ingår i: European Radiology, ISSN 0938-7994, E-ISSN 1432-1084, Vol. 20, nr 3, s. 725-733Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose  To assess patient skin and eye lens doses in interventional neuroradiology and to assess both stochastic and deterministic radiation risks. Methods  Kerma–area product (P KA) was recorded and skin doses measured using thermoluminescence dosimeters. Estimated dose at interventional reference point (IRP) was compared with measured absorbed doses. Results  The average and maximum fluoroscopy times were 32 and 189 min for coiling and 40 and 144 min for embolisation. The average and maximum P KA for coiling were 121 and 436 Gy cm2, respectively, and 189 and 677 Gy cm2 for embolisation. The average and maximum values of the measured maximum absorbed skin doses were 0.72 and 3.0 Sv, respectively, for coiling and 0.79 and 2.1 Sv for embolisation. Two out of the 52 patients received skin doses in excess of 2 Sv. The average and maximum doses to the eye lens (left eye) were 51 and 515 mSv (coiling) and 71 and 289 mSv (embolisation). Conclusion  The ratio between the measured dose and the dose at the IRP was 0.44 ± 0.18 mSv/mGy indicating that the dose displayed by the x-ray unit overestimates the maximum skin dose but is still a valuable indication of the dose. The risk of inducing skin erythema and lens cataract during our hospital procedures is therefore small.

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    FULLTEXT01
  • 194.
    Sandborg, Michael
    et al.
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Tingberg, Anders
    Dance, David
    Lanhede, Birgitta
    Almén, Anja
    Mc Vey, Graham
    Sund, Patrick
    Besjakow, Jack
    Mattson, Sören
    Månsson, Lars-Gunnar
    Alm Carlsson, Gudrun
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Demonstration of correlations between clinical and physical image quality measures in chest and lumbar spine screen-film radiography2001Ingår i: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 74, nr 882, s. 520-528Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The ability to predict clinical image quality from physical measures is useful for optimization in diagnostic radiology. In this work, clinical and physical assessments of image quality are compared and correlations between the two are derived. Clinical assessment has been made by a group of expert radiologists who evaluated fulfilment of the European image criteria for chest and lumbar spine radiography using two scoring methods: image criteria score (ICS) and visual grading analysis score (VGAS). Physical image quality measures were calculated using a Monte Carlo simulation model of the complete imaging system. This model includes a voxelized male anatomy and was used to calculate contrast and signal-to-noise ratio of various important anatomical details and measures of dynamic range. Correlations between the physical image quality measures on the one hand and the ICS and VGAS on the other were sought. 16 chest and 4 lumbar spine imaging system configurations were compared in frontal projection. A statistically significant correlation with clinical image quality was found in chest posteroanterior radiography for the contrast of blood vessels in the retrocardiac area and a measure of useful dynamic range. In lumbar spine anteroposterior radiography, a similar significant correlation with clinical image quality was found between the contrast and signal-to-noise ratio of the trabecular structures in the L1-L5 vertebrae. The significant correlation shows that clinical image quality can, at least in some cases, be predicted from appropriate measures of physical image quality.

  • 195.
    Sandborg, Michael
    et al.
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Tingberg, Anders
    Sund, Patrik
    McVey, Graham
    Dance, David
    Alm Carlsson, Gudrun
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Demonstration of correlation between physical and clinical image quality measures in chest and lumbar spine imaging.2000Ingår i: Digest of papers of the 2000 world congress on medical physics. CD-Rom Chicago July 23-28,2000, IEEE , 2000, s. 3078-3081 vol.4Konferensbidrag (Refereegranskat)
    Abstract [en]

    Clinical and physical assessments of image quality are compared and the correlation between the two derived. Clinical assessment has been made by a group of expert radiologists who evaluated the fulfillment of the European Image Criteria for chest and lumbar spine radiography; yielding the so-called Image Criteria Score, ICS. Physical measures of image quality were calculated using a Monte Carlo model of the complete imaging system. This model includes a voxelised male anatomy and calculates contrast and signal-to-noise ratio of various anatomical details and a measure of useful dynamic range. Correlations between the ICS and the physical image quality measures were sought. Four lumbar spine and 16 chest imaging systems were evaluated and simulated with the model. The most useful physical quantities for chest radiography were the dynamic range and contrast of blood vessels in the retro-cardiac area. In lumbar spine, it was the signal-to-noise ratio of trabecular structures. The significant correlation is encouraging and shows that clinical image quality can be predicted provided the imaging conditions are well known and that relevant measures of physical image quality are used to assess the quality of the image

  • 196.
    Sandborg, Michael
    et al.
    Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Önnerth, Magnus
    Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Linköpings universitet, Hälsouniversitetet.
    Comparison of human observer efficiency in pelvis radiographs in two different anatomical regions2004Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The performance of an x-ray imaging system is often evaluated in terms of how well low-contrast details are visualised in the images. It is however difficult to obtain reliable results because a threshold for human visibility does not strictly exist. The degree of how well a low-contrast detail is ‘seen’ varies from ‘not seen’ to ‘clearly seen’ related to the certainty (or level of confidence) of detection. The visibility criterion is difficult to define, communicate and maintain which results in comparably large inter- and intraobserver variability.

    The detection probability depends not only on the imaging task, the technical performance of the imaging system and the observer´s skill and training but also on the projected anatomy in the region where the detail (i.e. lung nodule) is situated. This has been explored by Kundel et al (1985), Samei et al (1999), Håkansson et al (2004), and in Båth et al (2004) by ROC studies mainly in chest radiography.

    In this work, human observer detection efficiency was measured in a pelvis anthropomorphic phantom. Low-contrast lesions were constructed and positioned in two different regions, one region with a fairly homogeneous, the other region with a heterogeneous anatomical background. A group of human observers were asked to identify the lesion in a set of two-alternative forced choice (2-AFC) experiments.

    Ladda ner fulltext (pdf)
    Comparison of human observer efficiency in pelvis radiographs in two different anatomical regions
  • 197.
    Sandborg, Mickael
    Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Radiography and Flouroscopy: Physical principles and biohazards1995Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Diagnostic radiology has come a long way since the discovery of ‘A New Kind of Rays’ in Würzburg by Professor Wilhelm Conrad Röntgen in November 1895. Professor Röntgen called the unknown rays ‘X rays’, but they are also, most appropriately and less mysteriously, referred to as Röntgen rays after their discoverer. In the last decades, imaging techniques using X rays has developed rapidly and play an important role in modern health care.

    The benefit of an X-ray examination for a patient could be assessed as how the patient’s risk situation is affected. The medical condition or illness leading to the examination may imply an increased risk of deteriorating health. Correct diagnosis and proper treatment, based on the information in the X-ray image, could lower the patient’s risk. For the individual the risks associated with the X-ray examination itself are small as is the radiation risk (patient absorbed dose) for well-designed imaging systems. Since the number of individuals undergoing X-ray examinations is very large, the collective absorbed dose to the whole population will be significant. Medical X-ray examinations are the manmade source giving the single largest radiation burden to the population, e.g., consisting 87% of the total radiation burden in the United Kingdom. Failure to diagnose is probably the largest single risk for the patient, but for some patients adverse effects of injected contrast media may be potentially hazardous.

    Ladda ner fulltext (pdf)
    Radiography and Flouroscopy : Physical principles and biohazards
  • 198. Sastry, M
    et al.
    Gustafsson, Håkan
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiofysik.
    Lund, Anders
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Lund, Eva
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Medicinsk radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    51V(n,β)52Cr reaction for neutron dosimetry: Development and assessment of a spectrophotometric method for determination of Cr in vanadium at sub ppm level2004Ingår i: Spectrochimica Acta Part A - Molecular and Biomolecular Spectroscopy, ISSN 1386-1425, E-ISSN 1873-3557, Vol. 60, nr 10, s. 2363-2367Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    With a view to monitoring the changes in coloration caused by the nuclear reaction 51V(n,β)52Cr in solution of vanadyl sulphate and using it for neutron dosimetry, electronic absorption spectra of vanadyl sulphate solutions were investigated at different concentrations of chromate impurity in micromolar range. It was observed that the presence of chromate enhances the absorptivity over a wide wavelength range serving essentially as a colouring agent for vanadium matrix, presumably due to charge transfer process. The absorbance at 380nm varied linearly over a wide concentration range. The limit of detection of chromate obtained is shown to be adequate for detecting neutron-induced chemical transmutation of vanadium to chromium under standard reactor conditions, when used with long path length cells. It was observed that the absorbance does not change on electron irradiation, suggesting that radiolytic effects due to beta decay, if any, do not interfere in the measurement of neutron-induced changes. In addition to its potential for neutron dosimetry, this is the first report of a simple and direct method of estimation of Cr in vanadium matrix at sub ppm level.

  • 199. Sjoholm, B
    et al.
    Geijer, H
    Persliden, Jan
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Impact of digital imaging on radiation doses to the patient during X-ray examination of the urinary tract2005Ingår i: Acta Radiologica, ISSN 0284-1851, E-ISSN 1600-0455, Vol. 46, nr 6, s. 657-661Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose: To compare radiation doses given to patients undergoing IVU (intravenous urography) before and after digitalization of our X-ray department. Material and Methods: IVU examinations were monitored with dose area product meters before and after the X-ray department changed to digital techniques. The first step was a change from film-screen to storage phosphor plates, while the second step involved changing to a flat panel detector. Forty-two patients were included for the film-screen situation, 69 when using the storage phosphor plates, and 70 using the flat panel detector. Results: A dose reduction from 41.8 Gycm(2) to 31.5 Gycm(2) was achieved with the first step when the film-screen system was replaced with storage phosphor plates. A further reduction to 12.1 Gycm(2) was achieved using the flat panel detector. Conclusion: The introduction of the flat panel detectors made a considerable dose reduction possible.

  • 200.
    Slatkin, Daniel
    et al.
    Brookhaven National Laboratory.
    Spanne, Per
    Brookhaven National Laboratory.
    Dilmanian, Avraham
    Brookhaven National Laboratory.
    Sandborg, Michael
    Linköpings universitet, Institutionen för medicin och hälsa, Medicinsk radiofysik. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Microbeam Radiation Therapy1992Ingår i: Medical physics (Lancaster), ISSN 0094-2405, Vol. 19, s. 1395-1400Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It is proposed to carry out radiotherapy and radiosurgery for brain lesions by crossfiring an array of parallel, closely spaced microbeams of synchrotron-generated x rays several times through an isocentric target, each microbeam in the array having an 25-µm-wide adjustable-height rectangular cross section. The following inferences from the known tissue sparing of 22-MeV deuteron microbeams in the mouse brain and the following exemplary Monte Carlo computations indicate that endothelial cells in the brain that are lethally irradiated by any microbeam in an array of adequately spaced microbeams outside an isocentric target will be replaced by endothelial cells regenerated from microscopically contiguous, minimally irradiated endothelium in intermicrobeam segments of brain vasculature. Endothelial regeneration will prevent necrosis of the nontargeted parenchymal tissue. However, neoplastic and/or nonneoplastic targeted tissues at the isocenter will be so severely depleted of potentially mitotic endothelial and parenchymal cells by multiple overlapping microbeams that necrosis will ensue. The Monte Carlo computations simulate microbeam irradiations of a 16-cm diameter, 16-cm-long cylindrical human head phantom using 50-, 100-, and 150-keV monochromatic x rays.

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