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| 2. |
- Larsson, Erik, et al.
(författare)
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Mouse S-factors based on monte carlo simulations in the anatomical realistic Moby phantom for internal dosimetry
- 2007
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Ingår i: Cancer Biotherapy & Radiopharmaceuticals. - : Mary Ann Liebert Inc. - 1557-8852 .- 1084-9785. ; 22:3, s. 438-442
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Biokinetic and dosimetry studies in small animals often precede clinical radionuclide therapies. As in human studies, a reliable evaluation of therapeutic efficacy is essential and must be based on accurate dosimetry, which must be based on a realistic dosimetry model. The aim of this study was to evaluate the differences in the results when using a more anatomic realistic mouse phantom, as compared to previously mathematically described phantoms, based mainly on ellipsoids and cylinders. The difference in results from the two Monte Carlo codes, EGS4 and MCNPX 2.6a, was also evaluated. Methods: An anatomical correct mouse phantom (Moby) was developed by Segars et al. for the evaluation and optimization of the in vivo imaging of mice. The Moby phantom is based on surfaces, which allows for an easy and flexible definition of organ sizes. It includes respiratory movements and a beating heart. It also allows for a redefinition of the location of several internal organs. The execution of he Moby program generates a three-dimensional voxel-based phantom of a specified size, which was modified and used as input for Monte Carlo simulations of absorbed fractions and S-factors. The radiation transport was simulated both with the EGS4 system and the MCNPX 2.6a code. Calculations were done,for the radionuclides F-18, I-124, I-131, In-111, Lu-177, and Y-90. S-factors were calculated using in-house-developed IDL programs and compared with results from previously published models. Results: The comparison of S-factors obtained by the Moby model and mathematical phantoms showed that these, in many cases, were within the same range, whereas for some organs, they were underestimated in the mathematical phantoms. The results were closer to the more anatomically realistic phantom than to the mathematical phantoms, with some exceptions. When investing differences between MCNPX 2.6a and EGS4 using the Moby phantom, results indicated some differences in absorbed fractions for electrons. This reason may be owing to differences in the codes regarding the theory for which electron transport are simulated. Conclusions: It is possible to calculate S-factors that are specific for small animals, such as mice. The Moby phantom is useful as a dosimetry model because it is anatomically realistic, but still very flexible, with 35 accurately segmented regions.
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| 3. |
- Reinstrup, Peter, et al.
(författare)
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Regional cerebral metabolic rate (positron emission tomography) during inhalation of nitrous oxide 50% in humans
- 2008
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Ingår i: British Journal of Anaesthesia. - : Elsevier BV. - 1471-6771 .- 0007-0912. ; 100:1, s. 66-71
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Recent studies in man have shown that cerebral blood flow increases during inhalation of nitrous oxide (N2O), a finding which is believed to be a result of an increased cerebral metabolic rate (CMR). However, this has not previously been evaluated in man. METHODS: Regional CMR(glu) (rCMR(glu)) was measured three dimensionally with positron emission tomography (PET) after injection of 2-(18F)fluoro-2-deoxy-D-glucose in 10 spontaneously breathing men (mean age 31 yr) inhaling either N2O 50% in O2 30% or O2 30% in N2. RESULTS: Global CMR(glu) in young men was 27 (3) micromol 100 g(-1) min(-1) [mean (SD)]. Inhalation of N2O 50% did not change global CMR(glu) [30 (5) micromol 100 g(-1) min(-1)] significantly, but it changed the distribution of the metabolism in the brain (P<0.0001 analysis of variance). Compared with inhalation of O2 30% in N2, N2O 50% inhalation increased the metabolism in the basal ganglia [14 (17)%, P<0.05] and thalamus [22 (23) %, P<0.05]. There was a prolonged metabolic effect of N2O inhalation seen on a succeeding PET scan with oxygen-enriched air (P<0.0001) performed 1 h after the N2O administration. CONCLUSIONS: Inhalation of N2O 50% did not change global CMR(glu), but the metabolism increased in central brain structures, an effect that was still present 1 h after discontinuation of N2O.
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| 4. |
- Almqvist, Monica, et al.
(författare)
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European Medical Imaging Technology Training, EMIT – ett prisbelönt EU-utbildningsprojekt
- 2005
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Ingår i: [Host publication title missing].
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Konferensbidrag (refereegranskat)abstract
- I ett sameuropeiskt Leonardo da Vinci-projekt har utvecklats ett internationellt utbildnings- och praktikpa- ket för blivande sjukhusfysiker [1-3]. Utbildningspaketet innehåller praktiska och kliniska övningsuppgifter där delta- garna tränas i för en sjukhusfysiker vanligt förekommande arbetsuppgifter. Målet har varit att det skall ge sjukhusfysi- kern den praktiska kompetens som krävs av det europeiska regelverket inom ämnesområdena magnetresonans (MRI), ultraljud, röntgendiagnostik, nuklearmedicin och strålbe- handling. Utbildningsmaterialet är webbaserat med en stor bilddata- bas och används redan i nära 70 länder runt om i världen. EMIT-projektet (European Medical Imaging Technology Training) belönades i december 2004 med det första Leonar- do da Vinci priset som delades ut till de tre bästa av totalt 4000 EU-projekt inom praktisk yrkesrelaterad utbildning. I projektet har vi konfronterats med den pedagogiska ut- maningen att förmedla praktisk kunskap, i sjukhusmiljöer med mycket olika förutsättningar beroende på vilket land deltagarna arbetar i. En omöjlig uppgift kan tyckas, men eftersom materialet är sammanställt av några av Europas starkaste forsknings- och utbildningsgrupper inom respekti- ve område så har det visat sig vara en stor tillgång och varje användare utnyttjar materialet efter sina egna behov. En an- nan erfarenhet är samarbetet över nationsgränser där vi har utnyttjat och konfronterats med likheter och oliktänkande inte minst vad gäller pedagogik och didaktik. Vi har dessut- om fått ett stort kontaktnät och många goda vänner. Den här presentationen beskriver delar av utbildningspaketet och erfarenheter av samarbetsprojektet.
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| 5. |
- Bading, James R., et al.
(författare)
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Quantitative serial imaging of an I-124 anti-CEA monoclonal antibody in tumor-bearing mice
- 2008
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Ingår i: Cancer Biotherapy & Radiopharmaceuticals. - : Mary Ann Liebert Inc. - 1557-8852 .- 1084-9785. ; 23:4, s. 399-409
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The 4.2-day half-life I-124 favors its use for positron emission tomography (PET) of monoclonal antibodies (mAbs). However, high positron energy and beta(+)-associated cascade gamma rays pose image resolution and background noise problems for I-124. This study evaluated quantitative PET of an I-124 mAb in tumor-bearing mice. Methods: An R4 microPET (TM) (Siemens/CTIMI, Knoxville, TN) was used with standard energy and coincidence timing windows (350-750 keV and 6 ns, respectively), delayed random coincidence subtraction, iterative image reconstruction, and no attenuation or scatter correction. Image resolution, contrast, and response linearity were compared for I-124 and F-18, using phantoms. Nude mice bearing human colon tumors (LS-174T) were injected intravenously with a chimeric I-124 anti-CEA mAb (cT84.66) and imaged serially 1 hour to 7 clays postinjection. Venous blood was sampled to validate image-derived blood curves. Mice were sacrificed after the final scan, and the biodistribution of I-124 was measured by direct tissue assay. Images were converted to units of kBq/g for each tissue of interest by comparing the final scans with the direct assays. Results: Measured resolution (FWHM) 0-16 mm from? the scanner axis was. 2.3-2.7 mm for I-124 versus 1.9-2.0 mm for F-18. Due to true coincidence e vents between annihilation photons and cascade gamma rays, background was greater for I-124 than F-18, but the signal-to-background ratio was still more than 20, and I-124 image intensities varied linearly with activity concentration. Tissue-based calibration worked well (i.e., PET blood curves agreed with direct measurements within 12% at all time points), while calibration, based on a cylindrical phantom approximating the mouse body, yielded tumor quantitation that was 46%-66% low, compared with direct assay. Conclusions: Images of quantitative accuracy sufficient for biodistribution. measurements can be obtained from tumor-bearing mice by using I-124 anti-CEA mAbs with standard. microPET acquisition and processing techniques, provided the calibration is based on the direct assay of excised tissue samples.
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| 6. |
- Bardies, Manuel, et al.
(författare)
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Quantitative imaging for clinical dosimetry
- 2006
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier BV. - 0167-5087 .- 0168-9002. ; 569:2, s. 467-471
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Tidskriftsartikel (refereegranskat)abstract
- Patient-specific dosimetry in nuclear medicine is now a legal requirement in many countries throughout the EU for targeted radionuclide therapy (TRT) applications. In order to achieve that goal, an increased level of accuracy in dosimetry procedures is needed. Current research in nuclear medicine dosimetry should not only aim at developing new methods to assess the delivered radiation absorbed dose at the patient level, but also to ensure that the proposed methods can be put into practice in a sufficient number of institutions. A unified dosimetry methodology is required for making clinical outcome comparisons possible.
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| 7. |
- Feridani, Amir, et al.
(författare)
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Combined flow cytometry and confocal laser scanning microscopy for evaluation of BR96 antibody cancer cell targeting and internalization.
- 2007
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Ingår i: Cytometry Part A. - : Wiley. - 1552-4930 .- 1552-4922. ; 71A:6, s. 361-370
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Tidskriftsartikel (refereegranskat)abstract
- Background: Monoclonal antibodies (mAb) are important tools in the management of tumor disease, and the discovery of antibodies with both specific cancer cell targeting and capacity to enter the cells by internalization are critical to improve the therapeutic efficacy. Method: Antibody cancer cell targeting and internalization properties of fluoroscein-conjugated mAb made against Lewis Y (BR96) were evaluated quantitatively and qualitatively by means of flow cytometry (FCM) and confocal laser scanning microscopy (CLSM), respectively, on cells from a rat tumor cell line (BN7005-H1D2). Results: The study demonstrated a specific binding of BR96 to LewisY (LeY) located in the cell membrane and as BR96/LeY immunocomplexes (BR96/LeY) internalized into the cytoplasm. BR96/LeY was internalized into about 15% of the cells, usually distributed throughout the cytoplasm, but also located close to the nuclei. Cytotoxic effects by BR96 were indicated, and CLSM visualized subpopulations containing cells with bound or internalized BR96/LeY that possessed morphologically pyknotic nuclei and disrupted DNA. Conclusion: The spatial-temporal pattern by BR96 cell targeting and internalization processes of BR96/LeY into the cancer cells expressing LeY was demonstrated by FCM and CLSM. Used together, the FCM and CLSM techniques provide a valuable tool for preclinical analyses of antibody targeting and their capacities as carriers of cytotoxic conjugates for the use in cancer therapy.
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