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  • 1.
    Alm Carlsson, Gudrun
    et al.
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Ekberg, Stefan
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Helmrot, Ebba
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences.
    Lindström, Jan
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences.
    Lund, Eva
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences.
    Matscheko, Georg
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences.
    Nilsson, Håkan
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences.
    Persliden, Jan
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Sandborg, Michael
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Stenström, Mats
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences.
    Monte Carlo metoden: ett verktyg inom strålningsfysiken1995Report (Other academic)
    Abstract [sv]

    Detta kompendium är tänkt att användas som ett propedeutiskt kursmaterial för kursdeltagare i kursen "Monte Carlo simulering av foton- och elektrontransport vid diagnostiska och radioterapeutiska strålkvaliteter".

    Först följer en kort repetition av den grundläggande statistik som utnyt1jas i beräkningarna. Därefter följer en beskrivning av slumptal. det fundament som metoden bygger på. Vidare beskrivs val ur olika frekvensfunktioner. Valet kan även göras ur så kallade falska fördelningar för att reducera variansen i den skattade storheten. Metoderna belyses i ett avsnitt om problemlösningsmetodik. först i allmänna termer för att sen gå in på ett specifikt problem (Buffons nålproblem) där en analys och strukturering av problemet görs varefter flödesschema och kodning exemplifieras. Så följer två moment där en beskrivning görs av färderna av fotoner respektive elektroner genom materia. För elektronfärderna gör man en indelning i klass 1- och klass II-färder. Vad detta innebär och hur deltapartiklar tas om hand beskrivs i ett kapitel. Till sist kommer en kort introduktion till de tre laborationerna med laborationshandledningar. Speciell vikt har lagts vid att initiera laboranten att fundera på fysiken i de simulerade experimenten.

    Detta kompendium har tillkommit som examinationsarbete vid en kurs i "Monte Carlo simulering av foton- och elektrontransport vid diagnostiska och radioterapeutiska strålkvaliteter", med andra ord den kurs du själv nu ämnar studera. Författarna önskar dig lycka till med kursen och hoppas att du kommer att få glädje av den. Speciellt hoppas vi att denna skrift ska underlätta för dig att tillgodogöra dig informationen vid föreläsningarna och under laborationerna.

  • 2. Axelsson, B
    et al.
    Bodén, K
    Fransson, Sven Göran
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radiology. Östergötlands Läns Landsting, Heart Centre, Department of Cardiology.
    Hansson, I B
    Persliden, Jan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radio Physics.
    Witt, Hans
    A comparison of analogue and digital techniques in upper gastrointestinal examinations: absorbed dose and diagnostic quality of the images.2000In: European Radiology, ISSN 0938-7994, E-ISSN 1432-1084, Vol. 10, p. 1351-1354Article in journal (Refereed)
  • 3.
    Dance, David
    et al.
    Royal Marsden NHS Trust.
    Lester, Sonia
    n/a.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Care, Radiation Physics. Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, Faculty of Health Sciences.
    Sandborg, Michael
    Linköping University, Department of Medicine and Care, Radiation Physics. Linköping University, Center for Medical Image Science and Visualization, CMIV. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics. Linköping University, Faculty of Health Sciences.
    Persliden, Jan
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    The use of carbon fibre material in radiographic cassettes: estimation of the dose and contrast advantages1997In: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 70, p. 383-390Article in journal (Refereed)
    Abstract [en]

    A Monte Carlo simulation has been used to estimate the dose and contrast advantages of replacing radiographic cassette fronts fabricated from aluminium with cassette fronts fabricated from low atomic number material (carbon fibre). The simulation used a realistic imaging geometry and calculations were made both with and without an anti-scatter grid. Account was taken of the scatter generated in the cassette front and the effect of beam hardening on primary contrast. Dose and contrast were evaluated for a range of cassette front thicknesses and tube potentials (60-150 kV) as well as for four examinations representative of situations with varying amounts of scatter. The results with an anti-scatter grid show a clear dose and contrast advantage in all cases when an aluminium cassette front is replaced with a low attenuation cassette front. The contrast advantage is dependent upon the examination and is generally greater for imaging bony structures than for imaging soft tissue. If a 1.74 mm aluminium cassette front is compared with a 1.1 mm carbon fibre cassette front, then the dose advantages are 16%, 9%, 8% and 6% and the contrast advantages are 10%, 7%, 4% and 5% for the AP paediatric pelvis examination at 60 kV, the anteroposterior (AP) lumbar spine examination at 80 kV, the lateral lumbar spine examination at 100 kV and the posteroanterior (PA) chest examination at 150 kV, respectively. The results without an anti-scatter grid show an increased dose advantage when a low attenuation cassette front is used, but the contrast advantage is small and in some situations negative.

  • 4.
    Dance, David
    et al.
    n/a.
    Sandborg, Michael
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Center for Medical Image Science and Visualization, CMIV. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics. Linköping University, Faculty of Health Sciences.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Persliden, Jan
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Optimisation of the design of antiscatter grids by computer modelling1995In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 57, no 1, p. 207-210Article in journal (Refereed)
    Abstract [en]

    A Monte Carlo computer program has been developed to model diagnostic radiological examinations, and has been used to study and optimise the design of antiscatter grids. This is important because the use of an inappropriate or poorly designed grid can lead to increased patient dose. Optimal grid parameters may be different for large and small scattering volumes. The program treats the patient as a rectangular block of tissue and takes account of the grid and image receptor. Image quality is measured in terms of contrast and signal-to-noise ratio and patient risk in terms of mean absorbed dose. Test objects of appropriate size and composition are used in the calculation of these image quality parameters. A new performance comparison and optimisation procedure has been developed, and the program has been used to study grid design in screen-film and digital radiology for small, medium and large scattering volumes.

  • 5.
    Edoff, Karin
    et al.
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Hellman, John
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Persliden, Jan
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences.
    Hildebrand, Claes
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    The developmental skeletal growth in the rat foot is reduced after denervation1997In: Anatomy and Embryology, ISSN 0340-2061, E-ISSN 1432-0568, Vol. 195, no 6, p. 531-538Article in journal (Refereed)
    Abstract [en]

    It has long been known that bone is innervated. In recent years it has been suggested that the local nerves may influence the growth and metabolism of bone by way of neuropeptides. The transient local presence of nerve-containing cartilage canals just before formation of secondary ossification centres in rat knee epiphyses seems to support that view. The purpose of the present study was to see if denervation affects the developmental growth of metatarsal bones in the rat hindfoot. We made sciatic and femoral neurectomies in 7- day-old rat pups and examined the hindfeet at various times after surgery. Immunohistochemical analysis showed that denervation was complete. Radiographic examination revealed that the metatarsal bones were significantly shorter in denervated hindfeet 30 days after denervation (average relative shortening 9.9±2.3%). Measurements of total foot length showed that denervated feet were subnormally sized already five days postoperatively, before the onset of secondary ossification. The timing of the latter was not affected by denervation. Control rats subjected to tenotomies exhibited normal metatarsal bone lengths. On the basis of these results we suggest that the local nerves may influence the growth of immature bones but do not affect secondary ossification.

  • 6.
    Fransson, Sven Göran
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radiology. Östergötlands Läns Landsting, Heart Centre, Department of Cardiology.
    Persliden, Jan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radio Physics.
    Patient radiation exposure during coronary angiography and intervention2000In: Acta Radiologica, ISSN 0284-1851, E-ISSN 1600-0455, Vol. 41, no 2, p. 142-144Article in journal (Refereed)
    Abstract [en]

    Purpose: To prospectively register fluoroscopic and cine times in a random fashion, and to measure patient radiation exposure from routine coronary angiography and coronary balloon angioplasty. We also evaluated an optional dose reduction system used during interventions. Material and Methods: The incident radiation to the patient was measured as kerma area product (KAP) in Gycm2, obtained from an ionisation chamber mounted on the undercouch tube during 65 coronary angiography procedures and another 53 percutaneous transluminal coronary angioplasties (including 29 stent procedures), mostly directly following complete coronary angiography. Results and Conclusion: The values from coronary angiography were comparable to other reports with a mean fluoroscopic time of 4.4 min and a mean KAP value of 62.6 Gycm2. The corresponding figures from coronary balloon angioplasty without stenting were lower than otherwise reported, with 8.2 min and 47.9 Gycm2, respectively. The use of coronary stents did prolong the mean fluoroscopic time (10.5 min) but did not significantly enhance the patient mean radiation dose (51.4 Gycm2). The dose reduction technique resulted in a significant KAP value reduction of 57%. In conclusion, with regard to radiation exposure, coronary angiography and balloon angioplasty are considered safe procedures.

  • 7. Geijer, H
    et al.
    Persliden, Jan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radiation Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Radiation exposure and patient experience during percutaneous coronary intervention using radial and femoral artery access2004In: European Radiology, ISSN 0938-7994, E-ISSN 1432-1084, Vol. 14, no 9, p. 1674-1680Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to evaluate radiation dose and patient discomfort/pain in radial artery access vs femoral artery access in percutaneous coronary intervention (PCI). Dose-area product (DAP) was measured non-randomised for 114 procedures using femoral access and for 55 using radial access. The patients also responded to a questionnaire concerning discomfort and pain during and after the procedure. The mean DAP was 69.8 Gy cm2 using femoral access and 70.5 Gy cm2 using radial access. Separating the access site from confounding factors with a multiple regression, there was a 13% reduction in DAP when using radial access (p=0.038). Procedure times did not differ (p=0.81). Bed confinement was much longer in the femoral access group (448 vs 76 min, p=0.000). With femoral access, there was a significantly higher patient grading for chest (p=0.001) and back pain (p=0.003) during the procedure and for access site (p=0.000) and back pain (p=0.000) after the procedure. Thirty-two femoral access patients (28%) were given morphine-type analgesics in the post-procedure period compared to three radial access patients (5%, P=0.001). DAP does not increase when using radial instead of femoral access and the patients grade discomfort and pain much lower when using radial access. Radial access is thus beneficial to use.

  • 8. Geijer, H
    et al.
    Persliden, Jan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radiation Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Varied tube potential with constant effective dose at lumbar spine radiography using a flat-panel digital detector2005In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 114, no 1-3, p. 240-245Article in journal (Refereed)
    Abstract [en]

    The purpose of the study was to evaluate the image quality at different tube potential (kV) settings using anteroposterior lumbar spine radiography as a model. An Alderson phantom was used with a flat-panel detector. The tube potential varied between 48 and 125 kV while the tube charge (mAs) was adjusted to keep an effective dose of 0.11 mSv. Image quality was assessed with a visual grading analysis and with a CDRAD contrast-detail phantom together with a computer program. The VGA showed inferior image quality for the higher kV settings, ≥ 96 kV with similar results for the contrast-detail phantom. When keeping the effective dose fixed, it seems beneficial to reduce kV to get the best image quality despite the fact that the mAs is not as high as with automatic exposure. However, this cannot be done with automatic exposure, which is set for a constant detector dose.

  • 9.
    Geijer, Håkan
    et al.
    Department of Radiology, Örebro Medical Centre Hospital, Örebro, Sweden.
    Beckman, Karl-Wilhelm
    Department of Medical Physics, Örebro Medical Centre Hospital, Örebro, Sweden.
    Andersson, Tony
    Department of Radiology, Örebro Medical Centre Hospital, Örebro, Sweden.
    Persliden, Jan
    Department of Medical Physics, Örebro Medical Centre Hospital, Örebro, Sweden.
    Radiation dose optimization in coronary angiography and percutaneous coronary intervention (PCI): II. Clinical evaluation2002In: European Radiology, ISSN 0938-7994, E-ISSN 1432-1084, Vol. 12, no 11, p. 2813-2819Article in journal (Refereed)
    Abstract [en]

    In a previous part of this study, the fluoroscopy dose rate was reduced in a cardiac catheterization laboratory. The objectives of the present study were to evaluate the effects in a clinical population undergoing percutaneous coronary intervention (PCI) of the dose-reducing measures detailed previously. Kerma area-product (KAP) values were first recorded for 154 patients undergoing PCI. Then, the fluoroscopy KAP rate was reduced from 44 to 16 mGy cm2/s by increasing filtration and reducing the image intensifier dose request. After this optimization, KAP was recorded for another 138 PCI procedures. After adjustment for differing proportions of combined procedures (coronary angiography+PCI), the total KAP was reduced to 67% of the original value with a 95% confidence interval from 57 to 78%, statistically significant. The mean total KAP values were 93.6 Gy cm2 before and 69.1 Gy cm2 after optimization. The KAP for digital acquisition did not change significantly. It is possible to make a large dose reduction in PCI by reducing the fluoroscopy dose rate. This dose reduction is beneficial for both patients and staff.

  • 10.
    Geijer, Håkan
    et al.
    Department of Radiology, Örebro Medical Centre Hospital, Örebro, Sweden.
    Beckman, Karl-Wilhelm
    Department of Medical Physics, Örebro Medical Centre Hospital, Örebro, Sweden.
    Andersson, Torbjörn
    Department of Radiology, Örebro Medical Centre Hospital, Örebro, Sweden.
    Persliden, Jan
    Department of Medical Physics, Örebro Medical Centre Hospital, Örebro, Sweden.
    Image quality vs radiation dose for a flat-panel amorphous silicon detector: a phantom study2001In: European Radiology, ISSN 0938-7994, E-ISSN 1432-1084, Vol. 11, no 9, p. 1704-1709Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to investigate the image quality for a flat-panel amorphous silicon detector at various radiation dose settings and to compare the results with storage phosphor plates and a screen-film system. A CDRAD 2.0 contrast-detail phantom was imaged with a flat-panel detector (Philips Medical Systems, Eindhoven, The Netherlands) at three different dose levels with settings for intravenous urography. The same phantom was imaged with storage phosphor plates at a simulated system speed of 200 and a screen-film system with a system speed of 160. Entrance surface doses were recorded for all images. At each setting, three images were read by four independent observers. The flat-panel detector had equal image quality at less than half the radiation dose compared with storage phosphor plates. The difference was even larger when compared with film with the flat-panel detector having equal image quality at approximately one-fifth the dose. The flat-panel detector has a very favourable combination of image quality vs radiation dose compared with storage phosphor plates and screen film.

  • 11.
    Geijer, Håkan
    et al.
    Department of Radiology, Örebro University Hospital, Örebro, Sweden.
    Beckman, Karl-Wilhelm
    Department of Medical Physics, Örebro University Hospital, Örebro, Sweden.
    Andersson, Torbjörn
    Department of Radiology, Örebro University Hospital, Örebro, Sweden.
    Persliden, Jan
    Department of Medical Physics, Örebro University Hospital, Örebro, Sweden.
    Radiation dose optimization in coronary angiography and percutaneous coronary intervention (PCI): I. Experimental studies2002In: European Radiology, ISSN 0938-7994, E-ISSN 1432-1084, Vol. 12, no 10, p. 2571-2581Article in journal (Refereed)
    Abstract [en]

    The objectives of this study were to evaluate the influence on image quality and dose to the patient and operator of various equipment settings for percutaneous coronary intervention (PCI), and to optimize the set-up. With an Alderson phantom, different settings, such as projection, protective screens, filtration, image intensifier size and collimation, were evaluated. Kerma-area product (KAP) was recorded as a measure of patient dose and scattered radiation was measured with an ionization chamber. Effective dose for a standardized PCI procedure was measured with thermoluminescent dosimeters inside the phantom. Image quality was evaluated with a contrast-detail phantom. Based on these findings, the equipment set-up was optimized to a low fluoroscopy dose rate with a sufficient image quality. Several operating parameters affected dose, particularly scattered radiation. The optimization reduced the fluoroscopy KAP rate from 44 to 16 mGy cm2/s using 15 cm of acrylic. The effective dose was reduced from 13 to 4.6 mSv for a standardized PCI procedure. Radiation dose to patient and operator in PCI is heavily dependent on both equipment set-up and operating parameters which can be influenced by the operator. With a careful optimization, a large reduction of radiation dose is possible.

  • 12.
    Geijer, Håkan
    et al.
    Department of Radiology, Örebro Medical Centre Hospital, Örebro, Sweden.
    Beckman, Karl-Wilhelm
    Department of Medical Physics, Örebro Medical Centre Hospital, Örebro, Sweden.
    Jonsson, Berith
    Department of Medical Physics, Örebro Medical Centre Hospital, Örebro, Sweden.
    Andersson, Torbjörn
    Department of Radiology, Örebro Medical Centre Hospital, Örebro, Sweden.
    Persliden, Jan
    Department of Medical Physics, Örebro Medical Centre Hospital, Örebro, Sweden.
    Digital Radiography of Scoliosis with a Scanning Method: Initial Evaluation2001In: Radiology, ISSN 0033-8419, E-ISSN 1527-1315, Vol. 218, p. 402-410Article in journal (Refereed)
    Abstract [en]

    PURPOSE: To evaluate the radiation dose, image quality, and Cobb angle measurements obtained with a digital scanning method of scoliosis radiography.

    MATERIALS AND METHODS: Multiple images were reconstructed into one image at a workstation. A low-dose alternative was to use digital pulsed fluoroscopy. Dose measurements were performed with thermoluminescent dosimeters in an Alderson phantom. At the same time, kerma area-product values were recorded. A Monte Carlo dose calculation also was performed. Image quality was evaluated with a contrast-detail phantom and visual grading system. Angle measurements were evaluated with an angle phantom and measurements obtained on patient images.

    RESULTS: The effective radiation dose was 0.087 mSv for screen-film imaging, 0.16 mSv for digital exposure imaging, and 0.017 mSv for digital fluoroscopy; the corresponding kerma area-product values were 0.43, 0.87, and 0.097 Gy · cm2, respectively. The image quality of the digital exposure and screen-film images was about equal at visual grading, whereas fluoroscopy had lower image quality. The angle phantom had lower angle values with digital fluoroscopy, although the difference in measured angles was less than 0.5°. The patient images showed no difference in angles.

    CONCLUSION: The described digital scanning method has acceptable image quality and adequate accuracy in angle measurements. The radiation dose required for digital exposure imaging is higher than that required for screen-film imaging, but that required for digital fluoroscopy is much lower.

  • 13.
    Geijer, Håkan
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radiology.
    Beckman, KW
    Örebro.
    Andersson, T
    Örebro.
    Persliden, Jan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radio Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Radiation dose and image quality with a flat-panel amorphous silicon digital detector.2001In: Eur Radiol,2001, 2001, p. 280-280Conference paper (Refereed)
  • 14.
    Geijer, Håkan
    et al.
    Department of Radiology, Örebro Medical Centre Hospital, Örebro, Sweden.
    Verdonck, Bert
    Philips Medical Systems, Best, The Netherlands.
    Beckman, Karl-Wilhelm
    Department of Medical Physics, Örebro Medical Centre Hospital, Örebro, Sweden.
    Andersson, Torbjörn
    Department of Radiology, Örebro Medical Centre Hospital, Örebro, Sweden.
    Persliden, Jan
    Department of Medical Physics, Örebro Medical Centre Hospital, Örebro, Sweden.
    Digital Radiography of Scoliosis with a Scanning Method: Radiation Dose Optimization2003In: European Radiology, ISSN 0938-7994, E-ISSN 1432-1084, Vol. 13, no 3, p. 543-551Article in journal (Refereed)
    Abstract [en]

    The aim of this study was optimization of the radiation dose–image quality relationship for a digital scanning method of scoliosis radiography. The examination is performed as a digital multi-image translation scan that is reconstructed to a single image in a workstation. Entrance dose was recorded with thermoluminescent dosimeters placed dorsally on an Alderson phantom. At the same time, kerma area product (KAP) values were recorded. A Monte Carlo calculation of effective dose was also made. Image quality was evaluated with a contrast-detail phantom and Visual Grading. The radiation dose was reduced by lowering the image intensifier entrance dose request, adjusting pulse frequency and scan speed, and by raising tube voltage. The calculated effective dose was reduced from 0.15 to 0.05 mSv with reduction of KAP from 1.07 to 0.25 Gy cm2 and entrance dose from 0.90 to 0.21 mGy. The image quality was reduced with the Image Quality Figure going from 52 to 62 and a corresponding reduction in image quality as assessed with Visual Grading. The optimization resulted in a dose reduction to 31% of the original effective dose with an acceptable reduction in image quality considering the intended use of the images for angle measurements.

  • 15.
    Gunnarsson, Thorsteinn
    et al.
    Linköping University, Department of Neuroscience and Locomotion, Neurosurgery. Linköping University, Faculty of Health Sciences.
    Theodorsson, Annette
    Linköping University, Department of Neuroscience and Locomotion, Neurosurgery. Linköping University, Faculty of Health Sciences.
    Karlsson, Per
    Linköping University, Department of Neuroscience and Locomotion, Neurosurgery. Linköping University, Faculty of Health Sciences.
    Fridriksson, Steen
    Linköping University, Department of Neuroscience and Locomotion, Neurosurgery. Linköping University, Faculty of Health Sciences.
    Boström, Sverre
    Linköping University, Department of Neuroscience and Locomotion, Neurosurgery. Linköping University, Faculty of Health Sciences.
    Persliden, Jan
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences.
    Johansson, Ingegerd
    Hillman, Jan
    Linköping University, Department of Neuroscience and Locomotion, Neurosurgery. Linköping University, Faculty of Health Sciences.
    Mobile computerized tomography scanning in the neurosurgery intensive care unit: increase in patient safety and reduction of staff workload2000In: Journal of Neurosurgery, ISSN 0022-3085, E-ISSN 1933-0693, Vol. 93, no 3, p. 432-436Article in journal (Refereed)
    Abstract [en]

    Object. Transportation of unstable neurosurgical patients involves risks that may lead to further deterioration and secondary brain injury from perturbations in physiological parameters. Mobile computerized tomography (CT) head scanning in the neurosurgery intensive care (NICU) is a new technique that minimizes the need to transport unstable patients. The authors have been using this device since June 1997 and have developed their own method of scanning such patients.

    Methods. The scanning procedure and radiation safety measures are described. The complications that occurred in 89 patients during transportation and conventional head CT scanning at the Department of Radiology were studied prospectively. These complications were compared with the ones that occurred during mobile CT scanning in 50 patients in the NICU. The duration of the procedures was recorded, and an estimation of the staff workload was made. Two patient groups, defined as high- and medium-risk cases, were studied. Medical and/or technical complications occurred during conventional CT scanning in 25% and 20% of the patients in the high- and medium-risk groups, respectively. During mobile CT scanning complications occurred in 4.3% of the high-risk group and 0% of the medium-risk group. Mobile CT scanning also took significantly less time, and the estimated personnel cost was reduced.

    Conclusions. Mobile CT scanning in the NICU is safe. It minimizes the risk of physiological deterioration and technical mishaps linked to intrahospital transport, which may aggravate secondary brain injury. The time that patients have to remain outside the controlled environment of the NICU is minimized, and the staff's workload is decreased.

  • 16. Jangland, L
    et al.
    Sanner, E
    Persliden, Jan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Dose reduction in computed tomography by individualized scan protocols2004In: Acta Radiologica, ISSN 0284-1851, E-ISSN 1600-0455, Vol. 45, no 3, p. 301-307Article in journal (Refereed)
    Abstract [en]

    Purpose: To find a method of adjusting the mAs-value in relation to the size of the patient undergoing computed tomography (CT) examination as a means of minimizing the radiation dose to the patient. Material and Methods: A correction factor to be applied on the tube charge for each patient was calculated using two mathematical methods. This approach was tested on 4 Perspex phantoms of different sizes and geometries. Noise was measured in the images with and without use of the correction factors. Retrospectively, correction factors were calculated for 12 CT examinations of the abdomen and the dose reduction was estimated for these patient studies. Results: The variations in noise measured in the images of the different phantoms were dramatically reduced by both methods. The retrospectively performed patient study showed that the largest correction factor was 7 times greater than the smallest, which means that a dose reduction factor of 7 is possible in the extreme case. Conclusion: Our proposed methods of adjusting the applied tube charge (mAs-value) in relation to the size of the patient can be used on the vast majority of CT systems. The potential for dose reduction is great, especially for small patients.

  • 17.
    Jansson, Margareta
    et al.
    Department of Radiology, Örebro University Hospital, 701 85 Örebro, Sweden.
    Geijer, Håkan
    Department of Radiology, Örebro University Hospital, 701 85 Örebro, Sweden.
    Persliden, Jan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medical and Health Sciences, Radiation Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Andersson, Torbjörn
    Department of Radiology, Örebro University Hospital, 701 85 Örebro, Sweden.
    Reducing dose in urography while maintaining image quality - A comparison of storage phosphor plates and a flat-panel detector2006In: European Radiology, ISSN 0938-7994, E-ISSN 1432-1084, Vol. 16, no 1, p. 221-226Article in journal (Refereed)
    Abstract [en]

    The introduction of new flat-panel detector technology often forces us to accept too high dose levels as proposed by the manufacturers. We need a tool to compare the image quality of a new system with the accepted standard. The aim of this study was to obtain a comparable image quality for two systems - storage phosphor plates and a flat-panel system using intravenous urography (IVU) as a clinical model. The image quality figure was calculated using a contrast-detail phantom (CDRAD) for the two evaluated systems. This allowed us to set a dose for the flat-panel system that gave equivalent image quality to the storage phosphor plates. This reduced detector dose was used in an evaluation of clinical images to find out if the dose reduction from the phantom study indeed resulted in images of equal clinical image quality. The image quality was assessed using image criteria of the European guidelines for IVU with visual grading analysis. Equivalent image quality in image pairs was achieved at 30% of the dose. The CDRAD contrast-detail phantom makes it possible to find dose levels that give equal image quality using different imaging systems. © Springer-Verlag 2005.

  • 18. Johansson, B
    et al.
    Persson, Essie
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radio Physics.
    Westman, G
    Persliden, Jan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radio Physics.
    Phantom study of radiation doses outside the target volume, brachyterapy versus external radiotherapy of early breast cancer.2003In: Radiotherapy and Oncology, ISSN 0167-8140, E-ISSN 1879-0887, Vol. 69, p. 107-112Article in journal (Refereed)
  • 19.
    Lamm, Inger-Lena
    et al.
    Institutionen för radiofysik, Lunds Universitet.
    Persliden, Jan
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Modulationsöverföringsfunktionen (MTF): De matematiska grunderna med exempel1993Report (Other academic)
    Abstract [sv]

    Vid överföring av information kan man karakterisera ett överföringssystem på olika sätt. Man kan t.ex. ange hur en signal förstärks, hur den förvr~ngs (distorderas), hur mycket brus systemet innehåller etc.

    Ett bildgivande system kan i princip karakteriseras av ett objekt som ger en insignal till en detektor vars utsignal antagligen innehåller signal + brus. För att beskriva hur utsignalen ser ut i jämförelse med insignalen används flera begrepp som:

    • Punktspridningsfunktionen (PSF)
    • Linjespridningsfunktionen (LSF)
    • Halvvärdesbredden (FWHM)

    Inom bildöverförande system använder man sig av begreppet MTF (MTF= Modulation Transfer Eunction) .

    Vi skall i det följande gå igenom grunderna för MTF och även ge exempel på hur man beräknar MTF. Genom att införa Fourier-transformen kan man lättare beräkna MTF och vi kommer därför att beskriva denna. För mätning av MTF för olika system inom röntgendiagnostiken hänvisas-till litteraturen.

  • 20.
    Larsson, Peter
    et al.
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Malusek, Alexandr
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Persliden, Jan
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Energy dependence in KAP-meter calibration coefficients: Dependence on calibration method, type of KAP-meter, and added filter close to the KAP-meter2006In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560Article in journal (Refereed)
  • 21.
    Larsson, Peter
    et al.
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Persliden, Jan
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Ionization chambers for measuring air kerma integrated over beam area: Deviations in calibration values using simplified calibration methods1998In: Physics in Medicine and Biology, ISSN 0031-9155, Vol. 43, no 3, p. 599-607Article in journal (Refereed)
    Abstract [en]

    Calibrations of kerma-area product meters (KAP meters) are often performed using simplified methods. The accuracy thus obtained can be insufficient, especially when the KAP meters are used for optimizing radiological procedures. The deviations between the best available calibration factor (k) and the simplified calibration factor were measured at different clinical x-ray installations. Depending on the type of x-ray installation and calibration method, the quotient ranged from 0.83 to 1.19, reflecting the error made in practice using these methods. A simple alternative calibration method based on comparison with a KAP meter calibrated by the best available method is described. Depending on tube potential and the stability of the electrometers, the uncertainty in the calibration factor derived with this method was between 3.8% and 5.6% (at 95% confidence level).

  • 22.
    Larsson, Peter
    et al.
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Persliden, Jan
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Sandborg, Michael
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Transmission ionization chambers for measurements of air collision kerma integrated over beam area. Factors limiting the accuracy of calibration1996In: Physics in Medicine and Biology, ISSN 0031-9155, Vol. 41, no 11, p. 2381-2398Article in journal (Refereed)
    Abstract [en]

    Kerma - area product meters (KAP meters) are frequently used in diagnostic radiology to measure the integral of air-collision kerma over an area perpendicular to the x-ray beam. In this work, a precise method for calibrating a KAP meter to measure is described and calibration factors determined for a broad range of tube potentials (40 - 200 kV). The integral is determined using a large number of TL dosimeters spread over and outside the nominal field area defined as the area within 50% of maximum . The method is compared to a simplified calibration method which approximates the integral by multiplying the kerma in the centre of the field by the nominal field area . While the calibration factor using the precise method is independent of field area and distance from the source, that using the simplified method depends on both. This can be accounted for by field inhomogeneities caused by the heel effect, extrafocal radiation and scattered radiation from the KAP meter. The deviations between the calibration factors were as large as for collimator apertures of and distances from the source of 50 - 160 cm. The uncertainty in the calibration factor using the precise method was carefully evaluated and the expanded relative uncertainty estimated to be with a confidence level of 95%.

  • 23.
    Messner, Karola
    et al.
    Linköping University, Department of Neuroscience and Locomotion, Orthopaedics and Sports Medicine. Linköping University, Faculty of Health Sciences.
    Fahlgren, Anna
    Linköping University, Department of Neuroscience and Locomotion, Orthopaedics and Sports Medicine. Linköping University, Faculty of Health Sciences.
    Persliden, Jan
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences.
    Andersson, Britt-Marie
    Linköping University, Department of Neuroscience and Locomotion, Orthopaedics and Sports Medicine. Linköping University, Faculty of Health Sciences.
    Radiographic joint space narrowing and histologic changes in a rabbit meniscectomy model of early knee osteoarthrosis2001In: American Journal of Sports Medicine, ISSN 0363-5465, E-ISSN 1552-3365, Vol. 29, no 2, p. 151-160Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to compare weightbearing radiographs with histologic cartilage evaluation in a rabbit meniscectomy model of the early stage of osteoarthrosis. Fifteen rabbits had a medial meniscectomy performed in one knee and a sham operation in the other knee. Five rabbits each were sacrificed at 13, 25, and 40 weeks after surgery. Radiographic joint space width and histologic cartilage changes of the medial knee compartment were quantified. Five nonoperated knees and five knees in which the meniscus had been removed immediately before the evaluations served as control specimens. Overall, the joint space of the peripheral part of the medial knee compartment was narrower in knees operated on for meniscus removal than in sham-operated knees (P < 0.003). In the knees with the meniscus removed, more cartilage changes were seen at the joint surface area of contact on radiographs than in the sham-operated knees (P < 0.0015). Indeed, the area of contact had cartilage changes similar to those in the whole medial compartment. However, there was no correlation between the degree of histologic cartilage change and the corresponding joint space measurements. Joint space width as measured on weightbearing radiographs is reduced after meniscectomy in the rabbit, but it does not reflect the degree of cartilage damage of the loaded joint surfaces in early stages of osteoarthrosis.

  • 24.
    Norrman, E.
    et al.
    Department of Natural Sciences, Örebro University, S-70182 Örebro, Sweden.
    Persliden, Jan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    A factorial experiment on image quality and radiation dose2005In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 114, no 1-3, p. 246-252Article in journal (Refereed)
    Abstract [en]

    To find if factorial experiments can be used in the optimisation of diagnostic imaging, a factorial experiment was performed to investigate some of the factors that influence image quality, kerma area product (KAP) and effective dose (E). In a factorial experiment the factors are varied together instead of one at a time, making it possible to discover interactions between the factors as well as major effects. The factors studied were tube potential, tube loading, focus size and filtration. Each factor was set to two levels (low and high). The influence of the factors on the response variables (image quality, KAP and E) was studied using a direct digital detector. The major effects of each factor on the response variables were estimated as well as the interaction effects between factors. The image quality, KAP and E were mainly influenced by tube loading, tube potential and filtration. There were some active interactions, for example, between tube potential and filtration and between tube loading and filtration. The study shows that factorial experiments can be used to predict the influence of various parameters on image quality and radiation dose. © The Author 2005. Published by Oxford University Press. All rights reserved.

  • 25.
    Persliden, Jan
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Analys av filmkassation: Ett SSI-projekt1996Report (Other academic)
    Abstract [en]

    Reject analysis in a radiology department can play an important role in the quality assurance process. Reject analysis was performed in the Department of Radiology, University Hospital in Linköping, Sweden, during 22 weeks 1992 and 5 weeks 1994. Between the two occasions, an education and training program was carried through. The rejected films were classified acording to 6 criteria. The reject frequency was 9.9% before and 8.5% after. Faulty exposure and faulty positioning of the patient contributing with 53 % of all rejected films.

    It was shown that reject analysis can easily be carried through. Compared to reports from the literature, the level found here was neither high nor low. The decrease in reject frequency after the training program was low and probably not significant. Reducing the rejections results in reduced patient doses and lower costs for the films. However, too low frequencies may be an indication of accepting bad image quality and reduced diagnostic accuracy. In the future when digital equipment is more frequently introduced the rejection of films will decrease, but not necessarily the retakes. Here, measurements of mean absorbed doses to the patients may provide a better toal for quality assurance of the radiology department.

  • 26.
    Persliden, Jan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Digital radiology and the radiological protection of the patient2004In: European Radiology, Supplement, ISSN 1613-3749, Vol. 14, no 1, p. 50-58Article in journal (Refereed)
    Abstract [en]

    The wide dynamic range of the digital detectors and the capabilities of post-processing allow obtaining more information from the radiographic images and avoiding retakes. Using phosphor plates in the image formation process, it has been possible to lower the dose to the patient. In digital radiography, several authors report the possibility to substantially lower the radiation dose to the patient while maintaining or even increasing the image quality. In conventional radiography, increased patient dose results in a dark image. In digital radiography the brightness of the image does not depend on patient dose. High patient doses can result in low-noise, high-contrast digital images, therefore, optimization of examinations is of vital importance in digital radiography. Special emphasis should be directed to paediatrics. The digital technique is very useful in reducing the dose both in fluoroscopy and radiography, however, special procedures for children are needed. © Springer-Verlag 2004.

  • 27.
    Persliden, Jan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radiation Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Patient and staff doses in interventional X-ray procedures in Sweden2005In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 114, no 1-3, p. 150-157Article in journal (Refereed)
    Abstract [en]

    Interventional procedures in radiology are of concern because of irradiation doses to the patients and also to the staff. A questionnaire sent to all radiology departments in Sweden showed that 11,350 procedures were performed annually 1996-1997. In a follow-up study, data from patient procedures were recorded. Type of procedure, dose-area product (DAP) values, fluoroscopy times, number of radiography series and patient data were recorded. For some procedures, staff doses were measured. Skin doses to the patients were also calculated where possible. Results: A total of 380 interventional procedures were described. The procedures were grouped into cranial, neck and thorax, intestine and abdominal, uro/genital and pelvis and extremities. DAP and fluoroscopy times (mean values) were 200 Gy cm2 for 57 min, 57 Gy cm2 for 16 min, 270 Gy cm2 for 35 min, 212 Gy cm2 for 37 min, 67 Gy cm2 for 21 min, respectively, for the named procedures. Maximum patient skin doses exceeded threshold values for erythema (2 Gy) in cranial, neck/thorax and intestine/abdominal procedures. Effective doses to the patients could be high, 200 mSv. Conclusion: It was found that patient doses could exceed threshold values for skin erythema (2 Gy) and temporary epilation (3 Gy). Hence, the procedures require immediate improvement. © The Author 2005. Published by Oxford University Press. All rights reserved.

  • 28.
    Persliden, Jan
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radio Physics.
    Beckman, Karl-Wilhelm
    Geijer, Håkan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radiology.
    Andersson, Torbjörn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radiology.
    Dose-image optimisation in digital radiology with a direct digital detector: an example applied to pelvic examination2002In: European Radiology, ISSN 0938-7994, E-ISSN 1432-1084, Vol. 12, p. 1584-1588Article in journal (Refereed)
  • 29.
    Persliden, Jan
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radio Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Beckman, KW
    Örebro.
    Geijer, Håkan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radiology.
    Andersson, T
    Örebro.
    Optimisation of the relationship of the dose-image quality for a new direct digital detector.2001In: Eur Radiol,2001, 2001, p. 279-279Conference paper (Refereed)
  • 30.
    Persliden, Jan
    et al.
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Helmrot, Ebba
    Ryhov Hospital.
    Hjort, Per
    Ryhov Hospital.
    Resjö, Margareta
    Linköping University, Department of Medicine and Care, Radiation Physics. Linköping University, Faculty of Health Sciences.
    Dose and image quality in the comparison of analogue and digital techniques in paediatric urology examinations.2004In: European Radiology, ISSN 0938-7994, E-ISSN 1432-1084, Vol. 14, no 4, p. 638-644Article in journal (Refereed)
    Abstract [en]

    In paediatric radiology it has been recognised that children have a higher risk of developing cancer from the irradiation than adults (two to three times); therefore, increased attention has been directed towards the dose to the patient. In this study the effect on patient dose and image quality in replacing the exposure in micturating cystourethrography (MCUG) examinations with the stored fluoroscopy image has been investigated. In the intravenous urography (IVU) examination we compared analogue and digital image quality, but the dose measurements were performed on a phantom. Standard clinical X-ray equipment was used. Sixty-eight patients in each of two centres were studied for the MCUG. Doses were measured with a dose-area product (DAP) meter and the image quality was scored. A non-parametric statistical analysis was performed. For the IVU, a phantom was used in the dose measurements but clinical images were scored in the comparison between analogue and digital images. For the MCUG, replacing the exposure with stored fluoroscopy images lowered the DAP value from 0.77 to 0.50 Gy cm2. The image quality did not show any difference between the techniques; however, if reflux was to be graded, exposure was needed. For the IVU, the doses could be lowered by a factor of 3 using digital techniques. The image quality showed no statistical difference between the two techniques. There is a potential for a substantial dose reduction in both MUCG and IVU examinations using digital techniques.

  • 31.
    Persliden, Jan
    et al.
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Sandborg, Michael
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Center for Medical Image Science and Visualization, CMIV. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics. Linköping University, Faculty of Health Sciences.
    Conversion factors between the energy imparted to the patient and air collision kerma integrated over beam area in paediatric radiology1993In: Acta Radiologica, ISSN 0284-1851, E-ISSN 1600-0455, Vol. 34, p. 92-98Article in journal (Refereed)
    Abstract [en]

    n/a

  • 32.
    Pettersson, Håkan
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Fälth-Magnusson, Karin
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Pediatrics . Östergötlands Läns Landsting, Centre of Paediatrics and Gynecology and Obstetrics, Department of Paediatrics in Linköping.
    Persliden, Jan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Scott, M.
    Department of Statistics, University of Glasgow, Glasgow G12 8QW, United Kingdom.
    Radiation risk and cost-benefit analysis of a paediatric radiology procedure: Results from a national study2005In: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 78, no 925, p. 34-38Article in journal (Refereed)
    Abstract [en]

    A national study was performed to investigate radiation doses and associated risks to patients during X-ray fluoroscopy-guided small intestinal biopsies in the investigation of coeliac disease. Thermoluminescent dosemeters (TLD) and questionnaires were sent to 42 of the 43 paediatric departments in Sweden performing these biopsies. During the study period (2 × 3 weeks) 257 biopsies were recorded, representing about 10% of annually performed paediatric investigations. The results show that the absorbed dose during biopsy ranged from 0.04 mGy to 23.8 mGy (mean 1.87 mGy). The fluoroscopy time ranged from 2 s to 663 s (mean 60 s). The collective dose from the procedure amounts to 4.7 manSv year-1. Thus, the annual excess cancer mortality, including severe hereditary effects, can be estimated at 0.6-0.7 cases per year. However, significant dose saving can be obtained by proper choice of sedation and biopsy equipment. © 2005 The British Institute of Radiology.

  • 33.
    Pettersson, Håkan
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radio Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Helmrot, Ebba
    Sandborg, Michael
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radio Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Nilsson, Jonas
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radio Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Olsson, Sara
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radio Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Persliden, Jan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radio Physics.
    Cederlund, Torsten
    Prenatal radiation exposures at diagnostic procedures: mathods to identify exposed pregnant patients2002In: European IRPA Congress 2002, FlorensISBN 88-88648-09-7,2002, 2002Conference paper (Refereed)
  • 34.
    Sandborg, Michael
    et al.
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Center for Medical Image Science and Visualization, CMIV. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics. Linköping University, Faculty of Health Sciences.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Persliden, Jan
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Dance, David
    n/a.
    Comparison of different materials for test phantoms in diagnostic radiology1993In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 49, no 1, p. 345-347Article in journal (Refereed)
    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.

  • 35.
    Sandborg, Michael
    et al.
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Center for Medical Image Science and Visualization, CMIV. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics. Linköping University, Faculty of Health Sciences.
    Dance, David
    n/a.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, Faculty of Health Sciences.
    Persliden, Jan
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Monte Carlo study of grid performance in diagnostic radiology: factors which affect the selection of tube potential and grid ratio1993In: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 66, p. 1164-1176Article in journal (Refereed)
    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.

  • 36.
    Sandborg, Michael
    et al.
    Linköping University, Department of Medicine and Care, Radiation Physics. Linköping University, Center for Medical Image Science and Visualization, CMIV. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics. Linköping University, Faculty of Health Sciences.
    Dance, David
    The Royal Marsden Hospital.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Persliden, Jan
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Monte Carlo study of grid performance in diagnostic radiology: task dependent opti­misation for screen-film imaging1994In: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 67, p. 76-85Article in journal (Refereed)
    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.

  • 37.
    Sandborg, Michael
    et al.
    Linköping University, Department of Medicine and Care, Radiation Physics. Linköping University, Center for Medical Image Science and Visualization, CMIV. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics. Linköping University, Faculty of Health Sciences.
    Dance, David
    n/a.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Persliden, Jan
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Results from an optimisation of grid design in diagnostic radiology1995In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 57, no 1, p. 211-215Article in journal (Refereed)
    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.

  • 38.
    Sandborg, Michael
    et al.
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Center for Medical Image Science and Visualization, CMIV. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics. Linköping University, Faculty of Health Sciences.
    Dance, David
    n/a.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Center for Medical Image Science and Visualization, CMIV. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics. Linköping University, Faculty of Health Sciences.
    Persliden, Jan
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Selection of anti-scatter grids for different imaging tasks: the advantage of low atomic number cover and interspace materials1993In: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 66, p. 1151-1163Article in journal (Refereed)
    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.

  • 39.
    Sandborg, Michael
    et al.
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Center for Medical Image Science and Visualization, CMIV. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics. Linköping University, Faculty of Health Sciences.
    Dance, David
    n/a.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Care, Radiation Physics. Linköping University, Faculty of Health Sciences.
    Persliden, Jan
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Tapiovaara, Markku
    n/a.
    A Monte Carlo study of grid performance in diagnostic radiology: task-dependent opti­mization for digital imaging 1994In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 39, no 10, p. 1659-1676Article in journal (Refereed)
    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.

  • 40.
    Sandborg, Michael
    et al.
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Center for Medical Image Science and Visualization, CMIV. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics. Linköping University, Faculty of Health Sciences.
    Dance, David
    The Royal Marsden Hospital.
    Persliden, Jan
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
    A Monte Carlo program for the calculation of contrast, noise and absorbed dose in diagnostic radiology1994In: Computer Methods and Programs in Biomedicine, ISSN 0169-2607, E-ISSN 1872-7565, Vol. 42, no 3, p. 167-180Article in journal (Refereed)
    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.

  • 41.
    Sandborg, Michael
    et al.
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Dance, David R.
    Department of Medical Physics, The Royal Marsden Hospital, Fulham Road, SW3 6JJ London, United Kingdom.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Persliden, Jan
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    The choice of anti-scatter grids in diagnostic radiology: the optimization of image quality and absorbed dose1993Report (Other academic)
    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.

  • 42.
    Sandborg, Michael
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radio Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    McVey, Graham
    Dance, David
    Persliden, Jan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radio Physics.
    Alm Carlsson, Gudrun
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radio Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    A voxel phantom based Monte Carlo computer program for optimisation of chest and lumbar spine X ray imaging systems2000In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 90, no 1-2, p. 105-108Article in journal (Refereed)
    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.

  • 43.
    Sandborg, Michael
    et al.
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    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
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Persliden, Jan
    Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Collection and analysis of patient and image data for calibration of a voxelphantombased Monte Carlo code and for the modelling of important structures1997Report (Other academic)
    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.

  • 44. Sjoholm, B
    et al.
    Geijer, H
    Persliden, Jan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Impact of digital imaging on radiation doses to the patient during X-ray examination of the urinary tract2005In: Acta Radiologica, ISSN 0284-1851, E-ISSN 1600-0455, Vol. 46, no 6, p. 657-661Article in journal (Refereed)
    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.

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