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- Vatnitsky, S, et al.
(författare)
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Proton dosimetry intercomparison
- 1996
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Ingår i: Radiotherapy and Oncology. - 0167-8140 .- 1879-0887. ; 41:2, s. 169-77
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND PURPOSE: Methods for determining absorbed dose in clinical proton beams are based on dosimetry protocols provided by the AAPM and the ECHED. Both groups recommend the use of air-filled ionization chambers calibrated in terms of exposure or air kerma in a 60Co beam when a calorimeter or Faraday cup dosimeter is not available. The set of input data used in the AAPM and the ECHED protocols, especially proton stopping powers and w-value is different. In order to verify inter-institutional uniformity of proton beam calibration, the AAPM and the ECHED recommend periodic dosimetry intercomparisons. In this paper we report the results of an international proton dosimetry intercomparison which was held at Loma Linda University Medical Center. The goal of the intercomparison was two-fold: first, to estimate the consistency of absorbed dose delivered to patients among the participating facilities, and second, to evaluate the differences in absorbed dose determination due to differences in 60Co-based ionization chamber calibration protocols.MATERIALS AND METHODS: Thirteen institutions participated in an international proton dosimetry intercomparison. The measurements were performed in a 15-cm square field at a depth of 10 cm in both an unmodulated beam (nominal accelerator energy of 250 MeV) and a 6-cm modulated beam (nominal accelerator energy of 155 MeV), and also in a circular field of diameter 2.6 cm at a depth of 1.14 cm in a beam with 2.4 cm modulation (nominal accelerator energy of 100 MeV).RESULTS: The results of the intercomparison have shown that using ionization chambers with 60Co calibration factors traceable to standard laboratories, and institution-specific conversion factors and dose protocols, the absorbed dose specified to the patient would fall within 3% of the mean value. A single measurement using an ionization chamber with a proton chamber factor determined with a Faraday cup calibration differed from the mean by 8%.CONCLUSION: The adoption of a single ionization chamber dosimetry protocol and uniform conversion factors will establish agreement on proton absorbed dose to approximately 1.5%, consistent with that which has been observed in high-energy photon and electron dosimetry.
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- Ekstrom, M, et al.
(författare)
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mu SR investigation of single crystalline dysprosium
- 1997
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Ingår i: HYPERFINE INTERACTIONS. - : BALTZER SCI PUBL BV. - 0304-3843. ; 104:1-4, s. 281-285
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Muon spin rotation (mu SR) data on a single crystalline sample of Dy have been obtained as function of temperature and applied hydrostatic pressure. The discontinuity observed in our new data at the phase transition at 85 K strongly suggests that the muon
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| 5. |
- Finkelstein, LD, et al.
(författare)
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Band approach to the excitation-energy dependence of x-ray fluorescence of TiO2
- 1999
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Ingår i: PHYSICAL REVIEW B-CONDENSED MATTER. - : AMERICAN PHYSICAL SOC. - 0163-1829. ; 60:4, s. 2212-2217
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Excitation-energy dependence of Ti L-2,L-3 soft x-ray emission spectra (XES) of a TiO2 single crystal is measured near Ti 2p threshold using tuneable synchrotron radiation at excitation energies E-exc = 458.2-476.9 eV. It is found that the emission spectr
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| 6. |
- Frey, E, et al.
(författare)
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Determination of the universality class of gadolinium
- 1997
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Ingår i: PHYSICAL REVIEW LETTERS. - : AMERICAN PHYSICAL SOC. - 0031-9007. ; 79:25, s. 5142-5145
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We resolve a long-standing puzzle for the static and dynamic critical behavior of gadolinium by a combined theoretical and experimental investigation, It is shown that the spin dynamics of a ferromagnet with hcp lattice structure and a spin-spin interacti
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| 7. |
- Henneberger, S, et al.
(författare)
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mu SR investigations of gadolinium in the paramagnetic regime near the ferromagnetic transition
- 1997
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Ingår i: HYPERFINE INTERACTIONS. - : BALTZER SCI PUBL BV. - 0304-3843. ; 104:1-4, s. 301-306
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We report on the measurements of the muon relaxation rate in gadolinium (Gd) in the critical regime down to T - T-C = 0.1 K. The results are compared to the predictions of mode-coupling calculations for a uniaxial and dipolar ferromagnet. One observes tha
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- Midtvedt, K, et al.
(författare)
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Routine perioperative antibiotic prophylaxis in renal transplantation
- 1998
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Ingår i: Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association. - : Oxford University Press (OUP). - 0931-0509. ; 13:7, s. 1637-1641
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 9. |
- Rampe, A, et al.
(författare)
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Magnetic linear dichroism in valence-band photoemission: Experimental and theoretical study of Fe(110)
- 1998
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Ingår i: PHYSICAL REVIEW B-CONDENSED MATTER. - : AMERICAN PHYSICAL SOC. - 0163-1829. ; 57:22, s. 14370-14380
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Magnetic linear dichroism (MLD) in angle-resolved valence-band photoemission of Fe(110) has been investigated by means of symmetry considerations, analytical theory, numerical calculations, and photoemission measurements. The dichroic photoemission spectr
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| 10. |
- Schreier, E, et al.
(författare)
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High pressure mu SR studies on single crystalline gadolinium
- 1997
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Ingår i: HYPERFINE INTERACTIONS. - : BALTZER SCI PUBL BV. - 0304-3843. ; 104:1-4, s. 311-317
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Muon spin rotation data on a single crystalline gadolinium sample have been obtained as function of temperature and hydrostatic external pressure up to 0.6 GPa. In the ferromagnetic state the application of pressure has a strong influence on the whole spi
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