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  • 1
    ISSN: 1619-7089
    Keywords: Oxygen-15 labelled butanol ; Pharmacokinetics ; Dosimetry ; Cerebral blood flow ; Positron emission tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In this positron emission tomography (PET) study in humans we determined the pharmacokinetics and radiation dose of oxygen-15 labelled butanol, a recently introduced tracer for regional cerebral blood flow (rCBF). This report includes a description of the automated preparation of 150-butanol which allows repetitive activation studies, each 15 min apart. Dynamic rCBF studies were extended by prolonged measurements up to 15 min after injection over different organs such as brain, liver, kidneys and bladder. All measurements were done with a whole-body PET camera PC4096-15WB. Based on the pharmacokinetic data in 13 subjects the radiation doses to single organs were calculated according to MIRD pamphlet No. 11 and the effective dose defined by ICRP 60 as an indicator of radiation dose to the total body. The liver received the highest radiation dose of about 2.2 mGy per 1500 MBq of injected 15O-butanol, which is the typical amount of administered tracer in one rCBF measurement. The dose to the kidneys was 1.6 mGy, to the stomach 0.8 mGy, and to the brain 0.16 mGy. The effective dose was 0.54 mGy, which was similar to that of H2 15O, but lower than the effective dose from C15O2 in amounts typically applied in human rCBF studies.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European journal of nuclear medicine 24 (1997), S. 1514-1521 
    ISSN: 1619-7089
    Keywords: Key words: Residence times ; Radiation dosimetry ; Excel ; MIRDOSE3Introduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. We developed a program which aims to facilitate the calculation of radiation doses to single organs and the whole body. IMEDOSE uses Excel to include calculations, graphical displays, and interactions with the user in a single general-purpose PC software tool. To start the procedure the input data are copied into a spreadsheet. They must represent percentage uptake values of several organs derived from measurements in animals or humans. To extrapolate these data up to seven half-lives of the radionuclide, fitting to one or two exponentional functions is included and can be checked by the user. By means of the approximate time-activity information the cumulated activity or residence times are calculated. Finally these data are combined with the absorbed fraction doses (S-values) given by MIRD pamphlet No. 11 to yield radiation doses, the effective dose equivalent and the effective dose. These results are presented in a final table. Interactions are realized with push-buttons and drop-down menus. Calculations use the Visual Basic tool of Excel. In order to test our program, biodistribution data of fluorine-18 fluorodeoxyglucose were taken from the literature (Meija et al., J Nucl Med 1991; 32:699–706). For a 70-kg adult the resulting radiation doses of all target organs listed in MIRD 11 were different from the ICRP 53 values by 1%±18% on the average. When the residence times were introduced into MIRDOSE3 (Stabin, J Nucl Med 1996; 37:538–546) the mean difference between our results and those of MIRDOSE3 was –3%±6%. Both outcomes indicate the validity of the present approach.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1619-7089
    Keywords: Key words: l-3-[I-123]iodo-α-methyltyrosine ; Dosimetry ; Brain tumours ; Amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The synthetic amino acid l-3-[123I]iodo-α-methyltyrosine (IMT) is currently under clinical evaluation as a single-photon emission tomography (SPET) tracer of amino acid uptake in brain tumours. So far, dosimetric data in respect of IMT are not available. Therefore we investigated the whole-body distribution of IMT in six patients with cerebral gliomas and the radiation doses were estimated. Whole-body scans were acquired at 1.5, 3 and 5 h after i.v. injection of 370–550 MBq IMT. The bladder was voided prior to each scan and the radioactivity excreted in the urine was measured. Based on the MIRD-11 method and the updated MIRDOSE3, the mean absorbed doses for various organs and the effective dose were calculated from geometric means of the anterior and posterior whole-body scans using seven source organs and the residence time. IMT was predominantly excreted by the kidneys (52.8%±11.5% at 1.5 h p.i., 63.0%±15.7% at 3 h p.i. and 74.6%±9.8% at 5 h p.i.). No organ system other than the urinary tract showed significant retention of the tracer. Early whole-body scans revealed slightly increased tracer uptake in the liver and in the bowel. Highest absorbed doses were found for the urinary bladder wall (0.047 mGy/MBq), the kidneys (0.010 mGy/MBq), the lower large intestinal wall (0.011 mGy/MBq) and the upper large intestinal wall (0.008 mGy/MBq). The effective dose according to ICRP 60 was estimated to be 0.0073 mSv/MBq for adults. This leads to an effective dose of 3.65 mSv in a typical brain SPET study using 500 MBq IMT. The MIRDOSE3 scheme yielded similar results. Thus, in spite of the relatively high tracer dose required for optimal brain scanning, radiation exposure in SPET studies with IMT is in the normal range of routine nuclear medicine investigations.
    Type of Medium: Electronic Resource
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