| 1. |
- Isaksson, M., et al.
(författare)
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Determination of the retention of 47Ca by whole-body counting
- 2000
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Ingår i: Applied Radiation and Isotopes. - 0969-8043 .- 1872-9800. ; 52:6, s. 1441-1450
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Tidskriftsartikel (refereegranskat)abstract
- Retention of intravenously or orally administered 47Ca in the human body are described by a two-parameter function. It is then sufficient to make only a few whole-body measurements to determine the retention function, avoiding faeces sampling and stool markers. Seven days after intake the non-absorbed calcium was excreted and the model agreed with the measured relative retention. Absorption of calcium could then, in some cases (e.g. comparative studies), be described by relative retention at the 7th day after intake. Copyright (C) 2000 Elsevier Science Ltd.
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| 2. |
- Jacobsson, S, et al.
(författare)
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A tomographic method for experimental verification of the integrity of spent nuclear fuel
- 2000
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Ingår i: Applied Radiation and Isotopes. - 0969-8043 .- 1872-9800. ; 53:4-5, s. 681-689
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Tidskriftsartikel (refereegranskat)abstract
- A tomographic method for verification of the integrity of spent nuclear fuel assemblies has been developed. The gamma radiation field emanating from emitted radiation from within the assembly is recorded and utilised for reconstructing the internal source
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| 3. |
- Lubberink, Mark, et al.
(författare)
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Quantification aspects of patient studies with 52Fe in positron emission tomography
- 1999
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Ingår i: Applied Radiation and Isotopes. - 0969-8043 .- 1872-9800. ; 51:6, s. 707-715
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Tidskriftsartikel (refereegranskat)abstract
- Quantification accuracy in positron emission tomography (PET) using non-pure positron emitters, such as 52Fe, may be influenced by gamma radiation emitted in the decay of these isotopes. High-energy positrons, emitted in the decay of the 52Fe-daughter 52mMn, also affect the quantification accuracy. A specific problem of the 52Fe/52mMn decay chain in vivo is that the kinetics of iron and manganese are different, and that PET cannot discriminate between the two nuclides. The effect of the decay properties of 52Fe/52mMn on the performance of PET was investigated using phantoms. Minor degradation in PET performance was found for 52Fe/52mMn compared to the pure low-energy positron emitter 18F. A method is presented to obtain a correction factor for the 52mMn radioactivity in blood. A model for correction of 52mMn-radioactivity in organs, based on existing data on manganese kinetics, is given. The presented corrections are discussed and illustrated in a patient study.
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| 4. |
- Nilsson, Jonas, 1969-, et al.
(författare)
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The effects of UV-irradiation on the ESR-dosimetry of tooth enamel
- 2001
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Ingår i: Applied Radiation and Isotopes. - 0969-8043 .- 1872-9800. ; 54:1, s. 131-139
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Tidskriftsartikel (refereegranskat)abstract
- Tooth enamel has been shown to be an excellent dosimeter material for retrospective dosimetry. A complication is that it is sensitive to ultraviolet light (UV), creating a signal that interferes with the dosimetric signal. Irradiation of tooth enamel by UV-light induces a mixture of stable and unstable free radicals. The unstable radicals disappear in about three weeks. Stable radicals are created both at the dosimetric peak and at the same g-value as the native peak. The stable peak coinciding with the native peak shows saturation behavior both for UVA/B- and UVC-light. The signal intensity from the sun is roughly estimated to induce a signal comparable to 15 mGy/h from 60 kV X-rays. The blue lamps used by dentists when hardening plastic repairs contain a narrow tail in the UVA/B-region, and it is shown here that these lamps also contribute to the stable peak coincident with the native peak. The contribution to the dosimetry peak, though negligible, at least for the irradiation times is used in this work. Most of the problems with UVA/B-induced signal contributions can probably be avoided by not using front teeth and teeth close to plastic repairs. (C) 2000 Elsevier Science Ltd.Tooth enamel has been shown to be an excellent dosimeter material for retrospective dosimetry. A complication is that it is sensitive to ultraviolet light (UV), creating a signal that interferes with the dosimetric signal. Irradiation of tooth enamel by UV-light induces a mixture of stable and unstable free radicals. The unstable radicals disappear in about three weeks. Stable radicals are created both at the dosimetric peak and at the same g-value as the native peak. The stable peak coinciding with the native peak shows saturation behavior both for UVA/B- and UVC-light. The signal intensity from the sun is roughly estimated to induce a signal comparable to 15 mGy/h from 60 kV X-rays. The blue lamps used by dentists when hardening plastic repairs contain a narrow tail in the UVA/B-region, and it is shown here that these lamps also contribute to the stable peak coincident with the native peak. The contribution to the dosimetry peak, though negligible, at least for the irradiation times is used in this work. Most of the problems with UVA/B-induced signal contributions can probably be avoided by not using front teeth and teeth close to plastic repairs.
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| 5. |
- Olsson, Sara, 1970-, et al.
(författare)
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Ammonium tartrate as an ESR dosimeter material
- 1999
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Ingår i: Applied Radiation and Isotopes. - 0969-8043 .- 1872-9800. ; 50:5, s. 955-965
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Tidskriftsartikel (refereegranskat)abstract
- This study is one step in the search for an ESR dosimeter material with a higher signal intensity than the commonly used l-α-alanine, to be useful in the clinical dose range (approximately 0.1–20 Gy). The substance ammonium tartrate was found and investigated regarding signal intensity, radical stability, dose response and dose resolution. The ESR signal intensity of ammonium tartrate was shown to be more than twice the intensity of the alanine signal. The data indicate that an unstable radiation induced radical contributes to the ESR signal initially; after a couple of hours it has converted to a secondary radical which has a decay slow enough to be considered stable during the first two weeks after irradiation. Ammonium tartrate has a linear dose response in the investigated range of 0.5–4000 Gy and a dose resolution of 0.1 Gy at the 0.5 Gy level where, as a comparison, the corresponding value for alanine is 0.3 Gy. We thus find the substance suitable for clinical dosimetry.
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| 6. |
- Olsson, Sara, et al.
(författare)
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Dose response and fading characteristics of an Alanine-Agarose gel
- 1996
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Ingår i: Applied Radiation and Isotopes. - 0969-8043 .- 1872-9800. ; 47:11-12, s. 1211-1217
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Tidskriftsartikel (refereegranskat)abstract
- The dose response of an alanine-agarose gel, analyzed by ESR spectrometry, and the stability of the radiation-induced free radicals have been investigated. The stability of the ESR signal is higher for dosimeter samples analyzed at 77 K than for dried samples, analyzed at room-temperature. The dose response is linear to within ±2% in the absorbed dose interval 2–100 Gy. The variations in spectral line shape were analyzed at temperatures between 77 and 270 K. The experimental ESR spectrum at 77 K was compared with a simulated spectrum of polycrystals of L-α-alanine.
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| 7. |
- Olsson, Sara K., 1970-, et al.
(författare)
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Development of ammonium tartrate as an ESR dosimeter material for clinical purposes
- 2000
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Ingår i: Applied Radiation and Isotopes. - 0969-8043 .- 1872-9800. ; 52:5, s. 1235-1241
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Tidskriftsartikel (refereegranskat)abstract
- The crystalline substance ammonium tartrate is investigated with respect to its suitability as a clinical dosimetry material. The properties investigated are: the radical stability for absorbed doses relevant for clinical use, the improvement in sensitivity when the crystals are deuterated and the linear electron tranfer (LET)-dependence. After photon irradiation to an absorbed dose of 20 Gy, the signal increases rapidly during the first 6 h. After this period, the changes are more moderate and can be corrected for. The signal-to-noise ratio of irradiated ammonium tartrate is twice the corresponding value of alanine. By deuterating the crystals, the sensitivity can be further improved by a factor of 1.4. As expected, the signal decreases with increasing LET of the radiation, but no changes in the spectrum shape was observed.
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| 8. |
- Tolmachev, Vladimir, et al.
(författare)
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Diffusion based separation methods : Dry distillation of zinc, cadmium and mercury isotopes from irradiated targets
- 1997
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Ingår i: Applied Radiation and Isotopes. - 0969-8043 .- 1872-9800. ; 48:5, s. 565-569
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Tidskriftsartikel (refereegranskat)abstract
- Diffusion-based separation methods allow the extraction of produced radionuclides with a low loss of target material, which is of special importance when enriched target material is used. We present a simple, non-destructive and rapid method to separate radioactive isotopes of IIB group elements (zinc, cadmium and mercury) from IB group metal targets irradiated with protons. Irradiated target foils were heated to a temperature 20°C below the melting point of the target materials. During these conditions at least 90% of the desired radioactivity was evaporated with negligible loss of target material. Separation time was 15 min for mercury, 60 min for cadmium and 120 min for zinc.
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| 9. |
- Tolmachev, Vladimir, et al.
(författare)
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Production of 61Cu from a natural nickel target
- 1998
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Ingår i: Applied Radiation and Isotopes. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0969-8043 .- 1872-9800. ; 49:1-2, s. 79-81
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Tidskriftsartikel (refereegranskat)
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| 10. |
- Vestad, T.A., et al.
(författare)
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EPR dosimetric properties of formates
- 2003
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Ingår i: Applied Radiation and Isotopes. - 0969-8043 .- 1872-9800. ; 59:2-3, s. 181-188
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Tidskriftsartikel (refereegranskat)abstract
- As a part of a program to develop an electron paramagnetic resonance (EPR) dosimeter suited for clinical use (doses in the cGy range), polycrystalline samples of lithium formate monohydrate (HCO2Li·H 2O), magnesium formate dihydrate (C2H2O 4Mg·2H2O), and calcium formate (C2H 2O4Ca) have been examined. L-Alanine was included for comparison and reference. Samples were irradiated with 60Co ?-rays and 60-220kV X-rays. The dosimeter response was assessed using the peak-to-peak amplitude of the first-derivative EPR spectrum. Dose-response curves for the 60Co ?-irradiated samples were constructed, and the dependences of the response on the photon energy, microwave power, and modulation amplitude were studied. Stability of the irradiation products upon storage (signal fading) was also investigated. Lithium formate monohydrate is by far the best candidate of the tested formates, suitable for measuring doses down to approximately 0.1Gy. Lithium formate monohydrate is more sensitive than alanine by a factor of 5.6-6.8 in the tested photon energy range, it exhibits no zero-dose signal and shows a linear dose response in the dose range from 0.2 to 1000Gy. Its EPR signal was found unchanged in shape and intensity 1 week after irradiation to 10Gy. Various less favorable properties rendered the other formates generally unsuitable, although calcium formate exhibits some interesting EPR dosimetric properties. © 2003 Elsevier Ltd. All rights reserved.
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