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Träfflista för sökning "hsv:(MEDICIN OCH HÄLSOVETENSKAP) hsv:(Klinisk medicin) hsv:(Radiologi och bildbehandling) srt2:(2010-2014);pers:(Leide Svegborn Sigrid)"

Sökning: hsv:(MEDICIN OCH HÄLSOVETENSKAP) hsv:(Klinisk medicin) hsv:(Radiologi och bildbehandling) > (2010-2014) > Leide Svegborn Sigrid

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1.
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2.
  • Giussani, Augusto, et al. (författare)
  • A Compartmental Model for Biokinetics and Dosimetry of 18F-Choline in Prostate Cancer Patients
  • 2012
  • Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 2159-662X. ; 53:6, s. 985-993
  • Tidskriftsartikel (refereegranskat)abstract
    • PET with F-18-choline (F-18-FCH) is used in the diagnosis of prostate cancer and its recurrences. In this work, biodistribution data from a recent study conducted at Skane University Hospital Malmo were used for the development of a biokinetic and dosimetric model. Methods: The biodistribution of F-18-FCH was followed for 10 patients using PET up to 4 h after administration. Activity concentrations in blood and urine samples were also determined. A compartmental model structure was developed, and values of the model parameters were obtained for each single patient and for a reference patient using a population kinetic approach. Radiation doses to the organs were determined using computational (voxel) phantoms for the determination of the S factors. Results: The model structure consists of a central exchange compartment (blood), 2 compartments each for the liver and kidneys, 1 for spleen, 1 for urinary bladder, and 1 generic compartment accounting for the remaining material. The model can successfully describe the individual patients' data. The parameters showing the greatest interindividual variations are the blood volume (the clearance process is rapid, and early blood data are not available for several patients) and the transfer out from liver (the physical half-life of F-18 is too short to follow this long-term process with the necessary accuracy). The organs receiving the highest doses are the kidneys (reference patient, 0.079 mGy/MBq; individual values, 0.033-0.105 mGy/MBq) and the liver (reference patient, 0.062 mGy/MBq; individual values, 0.036-0.082 mGy/MBq). The dose to the urinary bladder wall of the reference patient varies between 0.017 and 0.030 mGy/MBq, depending on the assumptions on bladder voiding. Conclusion: The model gives a satisfactory description of the biodistribution of F-18-FCH and realistic estimates of the radiation dose received by the patients.
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3.
  • Andersson, Martin, et al. (författare)
  • An internal radiation dosimetry computer program, IDAC 2.0, for estimation of patient doses from radiopharmaceuticals
  • 2014
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 162:3, s. 299-305
  • Tidskriftsartikel (refereegranskat)abstract
    • The internal dosimetry computer program internal dose assessment by computer (IDAC) for calculations of absorbed doses to organs and tissues as well as effective doses to patients from examinations with radiopharmaceuticals has been developed. The new version, IDAC2.0, incorporates the International Commission on Radiation Protection (ICRP)/ICRU computational adult male and female voxel phantoms and decay data from the ICRP publication 107. Instead of only 25 source and target regions, calculation can now be made with 63 source regions to 73 target regions. The major advantage of having the new phantom is that the calculations of the effective doses can be made with the latest tissue weighting factors of ICRP publication 103. IDAC2.0 uses the ICRP human alimentary tract (HAT) model for orally administrated activity and for excretion through the gastrointestinal tract and effective doses have been recalculated for radiopharmaceuticals that are orally administered. The results of the program are consistent with published data using the same specific absorption fractions and also compared with published data from the same computational phantoms but with segmentation of organs leading to another set of specific absorption fractions. The effective dose is recalculated for all the 34 radiopharmaceuticals that are administered orally and has been published by the ICRP. Using the new HAT model, new tissue weighting factors and the new adult computational voxel phantoms lead to an average effective dose of half of its earlier estimated value. The reduction mainly depends on electron transport simulations to walled organs and the transition from the stylised phantom with unrealistic interorgan distances to more realistic voxel phantoms.
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4.
  • Andersson, Martin, et al. (författare)
  • An upgrade of the internal dosimetry computer program IDAC
  • 2012
  • Ingår i: Medical Physics in the Baltic States. - : Kaunas University of Technology. - 1822-5721. ; , s. 120-123
  • Konferensbidrag (refereegranskat)abstract
    • A full update of the internal dosimetry computer program IDAC has been conducted. The new update is based on new and more accurate computational phantoms to calculate effective dose and absorbed dose to organs and tissues. The new ICRP Adult Reference Computational Phantoms has been adopted as well as the latest of the ICRP standardized biokinetic models. The updated computer program includes a user-friendly graphical user interface.
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5.
  • Andersson, Martin, et al. (författare)
  • Effective dose to adult patients from 338 radiopharmaceuticals estimated using ICRP biokinetic data, ICRP/ICRU computational reference phantoms and ICRP 2007 tissue weighting factors
  • 2014
  • Ingår i: EJNMMI Physics. - : Springer. - 2197-7364. ; 1:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Effective dose represents the potential risk to a population of stochastic effects of ionizing radiation (mainly lethal cancer). In recent years, there have been a number of revisions and updates influencing the way to estimate the effective dose. The aim of this work was to recalculate the effective dose values for the 338 different radiopharmaceuticals previously published by the International Commission on Radiological Protection (ICRP).Method: The new estimations are based on information on the cumulated activities per unit administered activity in various organs and tissues and for the various radiopharmaceuticals obtained from the ICRP publications 53, 80 and 106. The effective dose for adults was calculated using the new ICRP/International Commission on Radiation Units (ICRU) reference voxel phantoms and decay data from the ICRP publication 107. The ICRP human alimentary tract model has also been applied at the recalculations. The effective dose was calculated using the new tissue weighting factors from ICRP publications 103 and the prior factors from ICRP publication 60. The results of the new calculations were compared with the effective dose values published by the ICRP, which were generated with the Medical Internal Radiation Dose (MIRD) adult phantom and the tissue weighting factors from ICRP publication 60.Results: For 79% of the radiopharmaceuticals, the new calculations gave a lower effective dose per unit administered activity than earlier estimated. As a mean for all radiopharmaceuticals, the effective dose was 25% lower. The use of the new adult computational voxel phantoms has a larger impact on the change of effective doses than the change to new tissue weighting factors.Conclusion: The use of the new computational voxel phantoms and the new weighting factors has generated new effective dose estimations. These are supposed to result in more realistic estimations of the radiation risk to a population undergoing nuclear medicine investigations than hitherto available values.
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6.
  • Andersson, Martin, et al. (författare)
  • Improved estimates of the radiation absorbed dose to the urinary bladder wall
  • 2014
  • Ingår i: Physics in Medicine and Biology. - : Institute of Physics Publishing (IOPP). - 0031-9155 .- 1361-6560. ; 59:9, s. 2173-2182
  • Tidskriftsartikel (refereegranskat)abstract
    • Specific absorbed fractions (SAFs) have been calculated as a function of the content in the urinary bladder in order to allow more realistic calculations of the absorbed dose to the bladder wall. The SAFs were calculated using the urinary bladder anatomy from the ICRP male and female adult reference computational phantoms. The urinary bladder and its content were approximated by a sphere with a wall of constant mass, where the thickness of the wall depended on the amount of urine in the bladder. SAFs were calculated for males and females with 17 different urinary bladder volumes from 10 to 800 mL, using the Monte Carlo computer program MCNP5, at 25 energies of mono-energetic photons and electrons ranging from 10 KeV to 10 MeV. The decay was assumed to be homogeneously distributed in the urinary bladder content and the urinary bladder wall, and the mean absorbed dose to the urinary bladder wall was calculated. The Monte Carlo simulations were validated against measurements made with thermoluminescent dosimeters. The SAFs obtained for a urine volume of 200 mL were compared to the values calculated for the urinary bladder wall using the adult reference computational phantoms. The mean absorbed dose to the urinary wall from F-18-FDG was found to be 77 mu Gy/MBq formales and 86 mu Gy/MBq for females, while for (99)mTc-DTPA the mean absorbed doses were 80 mu Gy/MBq for males and 86 mu Gy/MBq for females. Compared to calculations using a constant value of the SAF from the adult reference computational phantoms, the mean absorbed doses to the bladder wall were 60% higher for F-18-FDG and 30% higher for (99)mTc-DTPA using the new SAFs.
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7.
  • Leide Svegborn, Sigrid (författare)
  • External radiation exposure of personnel in nuclear medicine from F-18, Tc-99m and I-131 with special reference to fingers, eyes and thyroid
  • 2012
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 149:2, s. 196-206
  • Tidskriftsartikel (refereegranskat)abstract
    • The radiation exposure of fingers, thyroid and eyes of workers handling radiopharmaceuticals during various nuclear medicine procedures was measured using thermoluminescent dosemeters. Dosemeters were placed on the finger tips of 19 workers on several different occasions for various procedures. Additionally, the routinely determined whole-body doses to various groups of workers were analysed. The finger dose measurements demonstrated clear differences between the various tasks, from 0.0012 µGy MBq(-1) (unpacking and installing (99)Mo/(99m)Tc-generator) to 3.0 µGy MBq(-1) (syringe withdrawal, injection and waste handling of (18)F-FDG). As long as the worker was handling (99m)Tc, the dose to the fingers was well below the ICRP dose limits, even when the activity was high. Special concern should, however, be devoted to the handling of (18)F, since the dose to the fingers could easily reach the dose limits. The estimated dose to eyes and thyroid was well below the dose limits. Since the introduction of the positron emission tomography/computed tomography facility, the annual whole-body dose has increased for those directly involved in the handling of (18)F. The annual whole-body dose of 0.2-2.5 mGy was, however, well below the dose limits.
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8.
  • Leide Svegborn, Sigrid (författare)
  • Radiation exposure of patients and personnel from a PET/CT procedure with F-18-FDG
  • 2010
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 139:1-3, s. 208-213
  • Tidskriftsartikel (refereegranskat)abstract
    • The positron emission tomography (PET)/computed tomography (CT) camera is a combination of a PET camera and a CT. The image from the PET camera is based on the detection of radiation that is emitted from a radioactive tracer, which has been given to the patient as an intravenous injection. The radiation that is emitted from the radioactive tracer is more energetic than any other radiation used in medical diagnostic procedures and this requires special radiation protection routines. The CT image is based on the detection of radiation produced from an X-ray tube and transmitted through the patient. The radiation exposure of the personnel during the CT procedure is generally very low. Regarding radiation exposure of the patient, it is important to notice whether a CT scan has been performed prior to the PET/CT in order to avoid any unnecessary irradiation. The total effective dose to the patient from a PET/CT procedure is approximately 10 mSv. The major part comes from internal irradiation due to radiopharmaceuticals within the patients (e.g. (18)F-FDG: approximately 6-7 mSv), and a minor part is due to the CT scan (low-dose CT scan: approximately 2-4 mSv). If a full diagnostic CT investigation is performed, the effective dose may be considerably higher. If the patient is pregnant, a PET/CT procedure should be avoided or postponed, unless it is vital for the patient. An interruption in breastfeeding is not necessary after a PET/CT procedure of the nursing mother. Close contact between the patient and a small child should however be avoided for a couple of hours after the administration of the radiopharmaceutical. The radiation dose to the personnel arises mainly due to handling of the radiopharmaceuticals (syringe withdrawal, injection, waste handling, etc.) and from close contact to the patient. This radiation dose can be limited by using the inverse-square law, i.e. by using the fact that the absorbed dose decreases substantially with increasing distance between the radiation source and the personnel.
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9.
  • Mattsson, Sören, et al. (författare)
  • Current activities in the ICRP concerning estimation of radiation doses to patients from radiopharmaceuticals for diagnostic use
  • 2011
  • Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 317, s. 012008-012008
  • Konferensbidrag (refereegranskat)abstract
    • A Task Group within the ICRP Committees 2 and 3 is continuously working to improve absorbed dose estimates to patients investigated with radiopharmaceuticals. The work deals with reviews of the literature, initiation of new or complementary studies of the biokinetics of a compound and dose estimates. Absorbed dose calculations for organs and tissues have up to now been carried out using the MIRD formalism. There is still a lack of necessary biokinetic data from measurements in humans. More time series obtained by nuclear medicine imaging techniques such as whole-body planar gamma-camera imaging, SPECT or PET are highly desirable for this purpose. In 2008, a new addendum to ICRP Publication 53 was published under the name of ICRP Publication 106 containing biokinetic data and absorbed dose information to organs and tissues of patients of various ages for radiopharmaceuticals in common use. That report also covers a number of generic models and realistic maximum models covering other large groups of substances (e.g. "(123)I-brain receptor substances"). Together with ICRP Publication 80, most radiopharmaceuticals in clinical use at the time of publication were covered except the radioiodine labeled compounds for which the ICRP dose estimates are still found in Publication 53. There is an increasing use of new radiopharmaceuticals, especially PET-tracers and the TG has recently finished its work with biokinetic and dosimetric data for (18)F-FET, (18)F-FLT and (18)F-choline. The work continues now with new data for (11)C-raclopride, (11)C-PiB and (123)I-ioflupan as well as re-evaluation of published data for (82)Rb-chloride, (18)F-fluoride and radioiodide. This paper summarises published ICRP-information on dose to patients from radiopharmaceuticals and gives some preliminary data for substances under review.
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10.
  • Stenström, Kristina, et al. (författare)
  • Local variations in C-14 - How is bomb-pulse dating of human tissues and cells affected?
  • 2010
  • Ingår i: Nuclear Instruments & Methods In Physics Research Section B-Beam Interactions With Materials And Atoms. - : Elsevier BV. - 0168-583X. ; 268:7-8, s. 1299-1302
  • Konferensbidrag (refereegranskat)abstract
    • Atmospheric nuclear weapons testing in the late 1950s and early 1960s almost doubled the amount of C-14 in the atmosphere. The resulting C-14 "bomb-pulse" has been shown to provide useful age information in e.g. forensic and environmental sciences, biology and the geosciences. The technique is also currently being used for retrospective cell dating in man, in order to provide insight into the rate of formation of new cells in the human body. Bomb-pulse dating relies on precise measurements of the declining C-14 concentration in atmospheric CO2 collected at clean-air sites. However, it is not always recognized that the calculations can be complicated in some cases by significant local variations in the specific activity of C-14 in carbon in the air and foodstuff. This paper presents investigations of local C-14 variations in the vicinities of nuclear installations and laboratories using C-14. Levels of C-14 in workers using this radioisotope are also discussed. (C) 2009 Elsevier B.V. All rights reserved.
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