| 1. |
- Dewaraja, Y K, et al.
(författare)
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Accurate dosimetry in I-131 radionuclide therapy using patient-specific, 3-dimensional methods for SPECT reconstruction and absorbed dose calculation
- 2005
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Ingår i: Journal of Nuclear Medicine. - 0161-5505. ; 46:5, s. 840-849
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Tidskriftsartikel (refereegranskat)abstract
- I-131 radionuclide therapy studies have not shown a strong relationship between tumor absorbed dose and response, possibly due to inaccuracies in activity quantification and dose estimation. The goal of this work was to establish the accuracy of I-131 activity quantification and absorbed dose estimation when patient-specific, 3-dimensional (3D) methods are used for SPECT reconstruction and for absorbed dose calculation. Methods: Clinically realistic voxel-phantom simulations were used in the evaluation of activity quantification and dosimetry. SPECT reconstruction was performed using an ordered-subsets expectation maximization (OSEM) algorithm with compensation for scatter, attenuation, and 3D detector response. Based on the SPECT image and a patient-specific density map derived from CT, 3D dosimetry was performed using a newly implemented Monte Carlo code. Dosimetry was evaluated by comparing mean absorbed dose estimates calculated directly from the defined phantom activity map with those calculated from the SPECT image of the phantom. Finally, the 3D methods were applied to a radioimmunotherapy patient, and the mean tumor absorbed dose from the new calculation was compared with that from conventional dosimetry obtained from conjugate-view imaging. Results: Overall, the accuracy of the SPECT-based absorbed dose estimates in the phantom was > 12% for targets down to 16 mL and up to 35% for the smallest 7-mL tumor. To improve accuracy in the smallest tumor, more OSEM iterations may be needed. The relative SD from multiple realizations was < 3% for all targets except for the smallest tumor. For the patient, the mean tumor absorbed dose estimate from the new Monte Carlo calculation was 7% higher than that from conventional dosimetry. Conclusion: For target sizes down to 16 mL, highly accurate and precise dosimetry can be obtained with 3D methods for SPECT reconstruction and absorbed dose estimation. In the future, these methods can be applied to patients to potentially establish correlations between tumor regression and the absorbed dose statistics from 3D dosimetry.
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| 4. |
- Weikert, S, et al.
(författare)
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Blood Pressure and Risk of Renal Cell Carcinoma in the European Prospective Investigation into Cancer and Nutrition
- 2008
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Ingår i: American Journal of Epidemiology. - : Oxford University Press (OUP). - 0002-9262 .- 1476-6256. ; 167:4, s. 438-446
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Tidskriftsartikel (refereegranskat)abstract
- Elevated blood pressure has been implicated as a risk factor for renal cell carcinoma (RCC), but prospective studies were confined to men and did not consider the effect of antihypertensive medication. The authors examined the relation among blood pressure, antihypertensive medication, and RCC in the European Prospective Investigation into Cancer and Nutrition (EPIC). Blood pressure was measured in 296,638 women and men, recruited in eight European countries during 1992-1998, 254,935 of whom provided information on antihypertensive medication. During a mean follow-up of 6.2 years, 250 cases of RCC were identified. Blood pressure was independently associated with risk of RCC. The relative risks for the highest versus the lowest category of systolic (>/=160 mmHg vs. <120 mmHg) and diastolic (>/=100 mmHg vs. <80 mmHg) blood pressures were 2.48 (95% confidence interval: 1.53, 4.02) and 2.34 (95% confidence interval: 1.54, 3.55). Risk estimates did not significantly differ according to sex or use of antihypertensive medication. Individuals taking antihypertensive drugs were not at a significantly increased risk unless blood pressure was poorly controlled. These results support the hypothesis that hypertension, rather than its medications, increases the risk of RCC in both sexes, while effective blood pressure control may lower the risk.
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- Brave, A, et al.
(författare)
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Vaccine delivery methods using viral vectors
- 2007
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Ingår i: Molecular pharmaceutics. - : American Chemical Society (ACS). - 1543-8384 .- 1543-8392. ; 4:1, s. 18-32
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Tidskriftsartikel (refereegranskat)
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| 9. |
- Huang, C, et al.
(författare)
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The inhomogeneous structure of water at ambient conditions
- 2009
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Ingår i: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 106:36, s. 15214-15218
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Tidskriftsartikel (refereegranskat)abstract
- Small-angle X-ray scattering (SAXS) is used to demonstrate the presence of density fluctuations in ambient water on a physical length-scale of approximate to 1 nm; this is retained with decreasing temperature while the magnitude is enhanced. In contrast, the magnitude of fluctuations in a normal liquid, such as CCl4, exhibits no enhancement with decreasing temperature, as is also the case for water from molecular dynamics simulations under ambient conditions. Based on X-ray emission spectroscopy and X-ray Raman scattering data we propose that the density difference contrast in SAXS is due to fluctuations between tetrahedral-like and hydrogen-bond distorted structures related to, respectively, low and high density water. We combine our experimental observations to propose a model of water as a temperature-dependent, fluctuating equilibrium between the two types of local structures driven by incommensurate requirements for minimizing enthalpy (strong near-tetrahedral hydrogen-bonds) and maximizing entropy (non-directional H-bonds and disorder). The present results provide experimental evidence that the extreme differences anticipated in the hydrogen-bonding environment in the deeply supercooled regime surprisingly remain in bulk water even at conditions ranging from ambient up to close to the boiling point.
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| 11. |
- Ljungberg, Jessica K
(författare)
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Cognitive degradation after exposure to combined noise and whole-body vibration in a simulated vehicle ride
- 2007
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Ingår i: International Journal of Vehicle Noise and Vibration (IJVNV). - : InderScience Publishers. - 1479-148X .- 1479-1471. ; 3:2, s. 130-142
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated if vehicle noise and whole-body vibrations produce negative after-effects on performance in an attention task and on ratings of alertness, difficulty, and annoyance. The task was applied before and after exposure, and after a rest. Participants had degraded performance immediately after exposure in all conditions, but no effect was found after the rest. No main effect was found between exposure conditions on performance, it was concluded that the degraded performance dependent on time was caused by fatigue. The results also suggested lower ratings of alertness and higher ratings of annoyance in the vibration condition compared to the control condition.
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| 12. |
- Ljungberg, Jessica K., 1971-, et al.
(författare)
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Stress, subjective experience and cognitive performance during exposure to noise an vibration
- 2007
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Ingår i: Journal of Environmental Psychology. - : Elsevier. - 0272-4944 .- 1522-9610. ; 27:1, s. 44-54
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates the effects of noise and whole-body vibration on saliva cortisol levels and subjectively rated difficulty and stress while performing cognitive tasks. In the first experiment, 24 men completed a logical reasoning task and a short-term memory task while, on separate occasions, being exposed to noise, vibration, combined stimuli, and control conditions. The environmental stimuli were designed to simulate the exposure from a forestry vehicle. The main finding was that participants made significantly higher ratings of stress when the noise stimulus was present, either alone or in combination with vibration. There were, however, some indications that noise sensitivity might moderate both subjective and objective measures such as higher ratings of stress and elevated cortisol levels in high noise sensitive participants. A second experiment was conducted where noise sensitivity was used as an inclusion criterion. A low sensitive and a high sensitive group were created, each containing 16 participants. The results of the second experiment, found only marginal effects of noise sensitivity and no effects at all on performance or cortisol. Increased ratings of stress and difficulty were found whenever either environmental stressor was present, whether by itself or in combination. The same result was seen even when pooling the data from both experiments. The main conclusion of the study is that relatively short exposures to noise and vibration typical of those levels that are found in industrial vehicles do not significantly affect performance in cognitive tasks nor saliva cortisol levels even if work in these environments can be experienced as more difficult or stressful.
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- Schulman, S., et al.
(författare)
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Post-thrombotic syndrome, recurrence, and death 10 years after the first episode of venous thromboembolism treated with warfarin for 6 weeks or 6 months
- 2006
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Ingår i: Journal of Thrombosis and Haemostasis. - : Elsevier BV. - 1538-7933 .- 1538-7836. ; 4:4, s. 734-742
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Tidskriftsartikel (refereegranskat)abstract
- Background: The influence of the duration of anticoagulant therapy after venous thromboembolism (VTE) on the long-term morbidity and mortality is unclear. Aim: To investigate the long-term sequelae of VTE in patients randomized to different duration of secondary prophylaxis. Methods: In a multicenter trial comparing secondary prophylaxis with vitamin K antagonists for 6 weeks or 6 months, we extended the originally planned 2 years follow-up to 10 years. The patients had annual visits and at the last visit clinical assessment of the post-thrombotic syndrome (PTS) was performed. Recurrent thromboembolism was adjudicated by a radiologist, blinded to treatment allocation. Causes of death were obtained from the Swedish Death Registry. Results: Of the 897 patients randomized, 545 could be evaluated at the 10 years follow-up. The probability of developing severe PTS was 6% and any sign of PTS was seen in 56.3% of the evaluated patients. In multivariate analysis, old age and signs of impaired circulation at discharge from the hospital were independent risk factors at baseline for development of PTS after 10 years. Recurrent thromboembolism occurred in 29.1% of the patients with a higher rate among males, older patients, those with permanent gering risk factor - especially with venous insufficiency at baseline - signs of impaired venous circulation at discharge, proximal deep vein thrombosis, or pulmonary embolism. Death occurred in 28.5%, which was a higher mortality than expected with a standardized incidence ratio (SIR) of 1.43 (95% CI 1.28-1.58), mainly because of a higher mortality than expected from cancer (SIR 1.83, 95% CI 1.44-2.23) or from myocardial infarction or stroke (SIR 1.28, 95% CI 1.00-1.56).The duration of anticoagulation did not have a statistically significant effect on any of the long-term outcomes. Conclusion: The morbidity and mortality during 10 years after the first episode of VTE is high and not reduced by extension of secondary prophylaxis from 6 weeks to 6 months. A strategy to reduce recurrence of VTE as well as mortality from arterial disease is needed. © 2006 International Society on Thrombosis and Haemostasis.
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