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- Aurumskjöld, Marie-Louise, et al.
(författare)
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Model based iterative reconstruction IMR gives possibility to evaluate thinner slice thicknesses than conventional iterative reconstruction iDose(4) - a phantom study
- 2015
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Ingår i: Medical Imaging 2015: Physics of Medical Imaging. - : SPIE. - 1996-756X .- 0277-786X. ; 9412, s. 94124-94124
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Konferensbidrag (refereegranskat)abstract
- Computed tomography (CT) is one of the most important modalities in a radiological department, which produces images with high diagnostic confidence, but in some cases contributes to a high radiation dose to the patient. The radiation dose can be reduced by the use of advanced image reconstruction algorithms. This study was done on a Philips Brilliance iCT with iterative reconstruction iDose(4) and model-based iterative reconstruction IMR. The purpose was to investigate the effect on the image quality with thin slice images reconstructed with IMR, compared to standard slice thickness reconstructed with iDose(4). Objective measurements of noise and contrast-to-noise ratio were performed using an image quality phantom, an anthropomorphic phantom and clinical cases. Subjective evaluations of low-contrast resolution were performed by observers using an image quality phantom. IMR gives strong noise reduction and enhanced low-contrast and thereby enable selection of thinner slice thickness. Objective evaluation of image noise shows that thin slices reconstructed with IMR provides lower noise than thicker slice images reconstructed with iDose(4). With IMR the slice thickness is of less importance for the noise. With thinner slices the partial volume artefacts becomes less pronounced. In conclusion, we have shown that IMR enables reduction of the slice thickness and at the same time maintain or even reduce the noise level compared to iDose(4) reconstruction with standard slice thickness. This will subsequently result in an improvement of image quality for images reconstructed with IMR.
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| 3. |
- Areberg, Johan, et al.
(författare)
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Antitumor effect of radioactive cisplatin (191Pt) on nude mice
- 2001
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Ingår i: International Journal of Radiation Oncology, Biology, Physics. - 0360-3016. ; 49:3, s. 827-832
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To investigate the effect of (191)Pt-cisplatin in vivo in terms of the antitumor effect and general toxicity on tumor-bearing nude mice. METHODS AND MATERIALS: Tumor-bearing (human squamous cell carcinoma, AB) nude mice were divided into four groups and given, i.p., physiological saline (controls), cisplatin, (191)Pt-cisplatin (80 MBq/mg), or (191)Pt-cisplatin (160 MBq/mg), respectively. Mortality and weight were used as parameters for monitoring general toxic effect, while specific growth delay (SGD) and the area under the logarithm of the relative tumor size curve (AUC-log[RTS]) were used to evaluate the antitumor effect of the treatments. RESULTS: Both SGD and AUC-log(RTS) values showed that (191)Pt-cisplatin was significantly (P < 0.05) more effective in retarding tumor growth than nonradioactive cisplatin. No differences in mortality between the different groups could be observed and no significant differences in weight change between the mice treated with cisplatin or (191)Pt-cisplatin could be seen. CONCLUSION: (191)Pt-cisplatin is a more effective drug than nonradioactive cisplatin in retarding tumor growth on nude mice without adding systemic toxic effects. We believe that radioactive cisplatin may prove to be an alternative to conventional cisplatin; however, the possible toxic effects on organs at risk have to be thoroughly investigated.
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| 4. |
- Arnoldsson, Kristina, 1961-, et al.
(författare)
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Retention and maternal transfer of environmentally relevant polybrominated dibenzo-p-dioxins and dibenzofurans, polychlorinated dibenzo-p-dioxins and dibenzofurans, and polychlorinated biphenyls in zebrafish (Danio rerio) after dietary exposure
- 2012
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Ingår i: Environmental Toxicology and Chemistry. - : John Wiley & Sons. - 0730-7268 .- 1552-8618. ; 31:4, s. 804-812
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Tidskriftsartikel (refereegranskat)abstract
- High levels of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), mono- and non-ortho polychlorinated biphenyls (PCBs), and polybrominated dibenzo-p-dioxins (PBDDs) are found in fish from coastal areas in the Baltic Sea, which may cause ecotoxicological effects. To increase our understanding of the persistency of the emerging pollutants polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs), fish feed was spiked with 21 PBDD/Fs, 17 PCDD/Fs, and 30 PCBs and fed to zebrafish. Concentrations in fish and eggs were examined during a six- or twelve-week uptake period, and a six-week elimination period. Steady-state was reached for 2, 3, 7, and/or 8-substituted tri- and tetra-BDD/Fs, with 2,3,7,8-tetra-BDD (2,3,7,8-TeBDD) being the most strongly retained. Steady-state was not reached for tetra- to hexa-CDDs. Non-2,3,7,8-congeners showed little of or no retention. Most PCBs had high retention and did not reach steady-state. Half-lives decreased in the order: PCBs > PCDD/Fs > PBDD/Fs. Concentrations of 2,3,7,8-penta- to octa-CDD/Fs decreased with their degree of chlorination suggesting that the rate-limiting factor for uptake is low bioavailability. Maternal transfer was observed for all retained compounds, with most transfer factors < 1, indicating that transfer rates are affected by the poor water solubility of the compounds. The limited retention of the major PBDD congeners found in Baltic Sea fish suggests that they are exposed to high or very high concentrations via either food or water.
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| 6. |
- Aurumskjöld, Marie-Louise, et al.
(författare)
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An investigation of the iterative reconstruction method iDose(4) on a Philips CT Brilliance 64 using a Catphan 600 phantom
- 2012
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Ingår i: Medical Imaging 2012: Physics of Medical Imaging. - : SPIE. - 0277-786X .- 1996-756X. ; 8313
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Konferensbidrag (refereegranskat)abstract
- The number of CT examinations giving a relatively high patient exposure is increasing. It is therefore important to optimize the imaging conditions at these investigations. Many steps have been taken to reduce the radiation doses in CT examinations. Currently much work is related to iterative image reconstruction methods as alternative to the filtered back projection method. The aim of this work was to evaluate quality parameters in images from a CT (Philips Brilliance 64) equipped with the iterative reconstruction method iDose(4) using a Catphan 600 phantom with and without body simulating ring. CT scans using abdomen protocol were taken with various tube currents and tube voltage and keeping collimation and pitch unchanged for all scans. All collected data were reconstructed with different levels of iDose(4) (Level 2, 4, 6) and traditional filtered back projection. Image quality parameters were evaluated using AutoQA Lite (TM) (Version 2.3 2007 Iris QA, LLC). Results from the study shows that the iterative reconstruction method decreases the noise with 15-45% compared with filtered back projection depending on which level of iDose(4) is used. The percentage reduction in noise level is the same with and without body simulating ring. Low contrast was improved with iDose(4) and spatial resolution is only marginally affected by the method of reconstruction. However by reducing the image noise, the detectability can be improved. Our conclusion is that there is great potential to reduce the noise and thereby improve the image quality by using iterative reconstruction methods. This can also be used to lower radiation dose and maintain image quality or improve image quality.
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| 9. |
- Bondesson, Eva, et al.
(författare)
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Planar gamma scintigraphy - points to consider when quantifying pulmonary dry powder aerosol deposition
- 2003
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Ingår i: International Journal of Pharmaceutics. - 1873-3476. ; 251:1-2, s. 33-47
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Tidskriftsartikel (refereegranskat)abstract
- Methodological aspects of planar gamma scintigraphy used to quantify pulmonary aerosol deposition were investigated using an experimental dry powder formulation. Particles of micronized salbutamol sulphate were labelled with technetium-99m and admixed to an ordered mixture of unlabelled micronized salbutamol sulphate and larger carrier particles of lactose. The radioaerosol was administered to 24 healthy subjects, 12 in each of two consecutive, similarly designed studies. Pulmonary deposition was determined using two methods: repeated planar imaging, and pharmacokinetic assessments following charcoal co-administration to prevent gastrointestinal salbutamol absorption. After due consideration had been taken to ensure appropriate radiolabelling, image acquisition and processing procedures, a scintigraphic estimate of 26.2% (24.2-28.4%) was obtained, which did not significantly differ from the pharmacokinetic estimate of 26.4% (24.4-28.7%). In summary, pre-study validation of the radiolabelling technique, quality control of radioaerosols produced during the study, correction for re-distribution of radiolabel from the lungs, selection of regions of interest, assessment of lung contours, correction for tissue attenuation of gamma rays and establishment of the actual recovery of radioactivity in the scintigraphic measurements could potentially affect the accuracy of the scintigraphic estimate of pulmonary deposition and, thus, should be carefully considered in the design or evaluation of any such study.
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