| 1. |
- Bolmsjö, Magnus S., et al.
(författare)
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Imaging 123I with a scintillation camera. A study of detection performance and quality factor concepts
- 1977
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Ingår i: Physics in Medicine and Biology. - : IOP Publishing. - 0031-9155. ; 22:2, s. 266-277
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Tidskriftsartikel (refereegranskat)abstract
- Image quality, resolution and sensitivity of a scintillation camera equipped with various collimators have been investigated using high purity 123I. Pulse height distributions of 123I from a thyroid phantom partly in air and partly immersed in water demonstrated the substantial septa penetration of the 440 and 529 keV gamma rays of 123I with high resolution collimators. Line spread functions were recorded and the modulation transfer function was evaluated from them. The two concepts of 'figure of merit' also used were QB=Sa mod MTF mod 2, where Sa is the plane sensitivity and QC=S2/(S+2B), where S is the true signal from the object and B is the total background or noise due to septa penetration and scatter.
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| 2. |
- Holm, Elis, et al.
(författare)
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Global fallout of curium
- 1978
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 273:5660, s. 289-290
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Tidskriftsartikel (refereegranskat)abstract
- THE search for 242mAm (t1/2=152 yr) in environmental samples has involved detection of its daughter 242Cm (t 1/2=163 d) (refs 1-3). These samples were contaminated by transuranium nuclides either from a nuclear fuel reprocessing plant or from a thermonuclear test fallout. A logical consequence was then to analyse global fallout-contaminated samples for 242Cm and 244Cm to establish the present distribution and global contamination of our environment by these transuranium elements. We have chosen the lichen Cladonia alpestris, which is an excellent bioindicator for atmospheric fallout and we present the results here. The samples have been stored in the laboratory for 5-16 yr. Thus, 242mAm and 242Cm were in sequelar radioactive equilibrium. The 242Cm present in the aged samples therefore represents the 242mAm present in the fallout. The results indicate a 242mAm/239+240Pu activity ratio of about 0.003% in global fallout.
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| 3. |
- Persson, Bertil R.R., et al.
(författare)
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Gel chromatography column scanning for the analysis of 99mTc-labelled compounds
- 1974
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Ingår i: Journal of Chromatography A. - 0021-9673. ; 101:2, s. 315-326
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Tidskriftsartikel (refereegranskat)abstract
- The gel chromatography column scanning (GCS) method has been studied, special attention being paid to its suitability for the analysis of 99mTc-labelled compounds and radio-pharmaceuticals. The sample to be analyzed was applied at the top of a column filled with Sephadex G gel. Elution was carried out with 0.9% sodium chloride solution with such a volume that all the radioactivity was retained in the column. The column was then sealed and scanned with a 1 mm slit-collimated NaI(Tl) crystal. The GCS method is discussed and different factors influencing the scanning profile are considered. The relationship between the position of the activity peak in the scanning profile and the molecular weight of the sample is given for Sephadex G-25 Medium gel.
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| 4. |
- Persson, Bertil R.R., et al.
(författare)
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Labeling plasmin with technetium-99m for scintigraphic localization of thrombi
- 1977
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Ingår i: International Journal of Applied Radiation and Isotopes. - 0020-708X. ; 28:1-2, s. 97-104
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Tidskriftsartikel (refereegranskat)abstract
- A detailed study has been made of the method for labeling plasmin (NOVO Indstri A/S Denmark) with 99mTc in order to prepare a radioactive indicator for early scintigraphic visualization of thrombi and tumors. The best method found for preparing 99mTc-plasmic involved the reduction of 2.5 ml 99mTc-pertechnetate solution with 0.5 ml of 4 mM SnCl2, 2 M NaCl and 70 mM HCl. This mixture was then added to 5 mg of plasmin to give a final pH of about 2. After 60 min of reaction the labeling efficiency was 80-90% as determined by gel chromatography column-scanning. The labeling kinetics and influence of pH, concentration of SnCl2, NaCl, plasmin and lysine were studied. The enzymatic activity of plasmin was reduced by less than 15% by the labeling process. Preliminary experiments in rabbits with artificially induced thrombi indicate accumulation of 99mTc activity in the same areas as 125I-fibrinogen after the administration of 99mTc-plasmin.
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| 5. |
- Strand, Sven Erik, et al.
(författare)
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The dual photopeak-area method applied to scintillation camera measurements of effective depth and activity of in vivo 123I-distributions
- 1977
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Ingår i: European Journal Of Nuclear Medicine. - 0340-6997. ; 2:2, s. 121-128
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Tidskriftsartikel (refereegranskat)abstract
- Attenuation curves and photopeak ratios of 159 keV and 28 keV phtons emitted in the decay of 123I have been studied using a scintillation camera equipped with an extra ADC for recording the pulse height distribution of the energy signal. Cavities of various sizes containing 123I-solution were placed at different depths in a water phantom in order to vary the effective depth, i.e., the thickness of attenuating material above the cavity plus the distance to the centre of activity in the cavity. The centre of activity varies with the distribution of activity in the cavity, size of cavity, and the effective attenuation coefficient derived from the attenuation curves. From the photopeak ratio an average effective depth is determined which can be used for calculating the attenuation correction factor. The dual photopeak ratio has been used in clinical evaluation of thyroid 123I uptake measurements where effective depths ranging from 21 to 43 mm were obtained for the activity in the thyroid. Applications of the photopeak ratio method for renography with 123I-hippuran and blood flow studies using 133Xe or 127Xe and studies with many other radionuclides are also discussed.
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| 6. |
- Persson, Bertil R.
(författare)
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90Sr in northern Sweden : Relationships and annual variations from 1961 to 1969 in lichen, reindeer and man
- 1971
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Ingår i: Health Physics. - : Ovid Technologies (Wolters Kluwer Health). - 0017-9078. ; 20:4, s. 393-402
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Tidskriftsartikel (refereegranskat)abstract
- The transport of fallout-90Sr has been investigated in the food-chain: Lichen-reindeer-man during 1961-1969. The maximum levels which occurred in lichen during 1963-1965 were about 13 nCi/kg dry wt. The90Sr-level in the lichen-carpet decreased to about 5 nCi/kg dry wt. in 1967-1969. The effective half-time of 90Sr in the lichen-carpet was estimated to be 2.5 ± 0.8 a. The vertical distribution of90Sr in the lichen-carpet was studied during 1966— 1969 and indicates an increased deposition of90Sr-fallout during 1968-1969. The90Sr/Ca-ratio has also been studied in reindeer-bone and muscle tissues. This ratio increased up to 1965 to about 700 pCi/g in reindeer-meat and to 1000pCi/g in bone, and then there was a decrease to about 400 pCi/g in both meat and bone in 1969. The seasonal variation of the 90Sr/Ca-ratio in reindeer-meat and bone since 1965 was evaluated from the 90Sr/Ca-ratio in lichen by using a three-compartment model for the Sr-retention in reindeer. The90Sr/Ca-ratio in the skeleton of adult Swedish Lapps was calculated from the 90Sr/Ca-ratio estimated for diet. The absorbed dose delivered by90Sr +90Y during the period 1950-1970 has been estimated to be 30 mrad to the endosteum (cells lining bone-surfaces) and 20 mrad to the active bone-marrow. Corresponding absorbed dose values for the whole period 1950-2000 were estimated to be 80 ± 15 mrad to the whole endosteum and 50 ± 10 mrad to the bone-marrow.
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