| 1. |
- Johansson, Dongni, 1988, et al.
(author)
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Individualization of levodopa treatment using a microtablet dispenser and ambulatory accelerometry
- 2018
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In: CNS Neuroscience & Therapeutics. - : Wiley. - 1755-5930 .- 1755-5949. ; 24:5, s. 439-447
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Journal article (peer-reviewed)abstract
- Aim: This 4-week open-label observational study describes the effect of introducing a microtablet dose dispenser and adjusting doses based on objective free-living motor symptom monitoring in individuals with Parkinson's disease (PD). Methods: Twenty-eight outpatients with PD on stable levodopa treatment with dose intervals of ≤4 hour had their daytime doses of levodopa replaced with levodopa/carbidopa microtablets, 5/1.25 mg (LC-5) delivered from a dose dispenser device with programmable reminders. After 2 weeks, doses were adjusted based on ambulatory accelerometry and clinical monitoring. Results: Twenty-four participants completed the study per protocol. The daily levodopa dose was increased by 15% (112 mg, P < 0.001) from period 1 to 2, and the dose interval was reduced by 12% (22 minutes, P = 0.003). The treatment adherence to LC-5 was high in both periods. The MDS-UPDRS parts II and III, disease-specific quality of life (PDQ-8), wearing-off symptoms (WOQ-19), and nonmotor symptoms (NMS Quest) improved after dose titration, but the generic quality-of-life measure EQ-5D-5L did not. Blinded expert evaluation of accelerometry results demonstrated improvement in 60% of subjects and worsening in 25%. Conclusions: The introduction of a levodopa microtablet dispenser and accelerometry aided dose adjustments improve PD symptoms and quality of life in the short term.
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| 2. |
- Nilsson, Erik, et al.
(author)
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The grade of individual prostate cancer lesions predicted by magnetic resonance imaging and positron emission tomography
- 2023
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In: Communications Medicine. - : Springer Nature. - 2730-664X. ; 3:1
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Journal article (peer-reviewed)abstract
- Background: Multiparametric magnetic resonance imaging (mpMRI) and positron emission tomography (PET) are widely used for the management of prostate cancer (PCa). However, how these modalities complement each other in PCa risk stratification is still largely unknown. We aim to provide insights into the potential of mpMRI and PET for PCa risk stratification.Methods: We analyzed data from 55 consecutive patients with elevated prostate-specific antigen and biopsy-proven PCa enrolled in a prospective study between December 2016 and December 2019. [68Ga]PSMA-11 PET (PSMA-PET), [11C]Acetate PET (Acetate-PET) and mpMRI were co-registered with whole-mount histopathology. Lower- and higher-grade lesions were defined by International Society of Urological Pathology (ISUP) grade groups (IGG). We used PET and mpMRI data to differentiate between grades in two cases: IGG 3 vs. IGG 2 (case 1) and IGG ≥ 3 vs. IGG ≤ 2 (case 2). The performance was evaluated by receiver operating characteristic (ROC) analysis.Results: We find that the maximum standardized uptake value (SUVmax) for PSMA-PET achieves the highest area under the ROC curve (AUC), with AUCs of 0.72 (case 1) and 0.79 (case 2). Combining the volume transfer constant, apparent diffusion coefficient and T2-weighted images (each normalized to non-malignant prostatic tissue) results in AUCs of 0.70 (case 1) and 0.70 (case 2). Adding PSMA-SUVmax increases the AUCs by 0.09 (p < 0.01) and 0.12 (p < 0.01), respectively.Conclusions: By co-registering whole-mount histopathology and in-vivo imaging we show that mpMRI and PET can distinguish between lower- and higher-grade prostate cancer, using partially discriminative cut-off values.
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| 3. |
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| 4. |
- Sandgren, Kristina, et al.
(author)
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Histopathology-validated lesion detection rates of clinically significant prostate cancer with mpMRI, [68Ga]PSMA-11-PET and [11C]Acetate-PET
- 2023
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In: Nuclear medicine communications. - : Lippincott Williams & Wilkins. - 0143-3636 .- 1473-5628. ; 44:11, s. 997-1004
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Journal article (peer-reviewed)abstract
- Objective: PET/CT and multiparametric MRI (mpMRI) are important diagnostic tools in clinically significant prostate cancer (csPC). The aim of this study was to compare csPC detection rates with [68Ga]PSMA-11-PET (PSMA)-PET, [11C] Acetate (ACE)-PET, and mpMRI with histopathology as reference, to identify the most suitable imaging modalities for subsequent hybrid imaging. An additional aim was to compare inter-reader variability to assess reproducibility.Methods: During 2016–2019, all study participants were examined with PSMA-PET/mpMRI and ACE-PET/CT prior to radical prostatectomy. PSMA-PET, ACE-PET and mpMRI were evaluated separately by two observers, and were compared with histopathology-defined csPC. Statistical analyses included two-sided McNemar test and index of specific agreement.Results: Fifty-five study participants were included, with 130 histopathological intraprostatic lesions >0.05 cc. Of these, 32% (42/130) were classified as csPC with ISUP grade ≥2 and volume >0.5 cc. PSMA-PET and mpMRI showed no difference in performance (P = 0.48), with mean csPC detection rate of 70% (29.5/42) and 74% (31/42), respectively, while with ACE-PET the mean csPC detection rate was 37% (15.5/42). Interobserver agreement was higher with PSMA-PET compared to mpMRI [79% (26/33) vs 67% (24/38)]. Including all detected lesions from each pair of observers, the detection rate increased to 90% (38/42) with mpMRI, and 79% (33/42) with PSMA-PET.Conclusion: PSMA-PET and mpMRI showed high csPC detection rates and superior performance compared to ACE-PET. The interobserver agreement indicates higher reproducibility with PSMA-PET. The combined result of all observers in both PSMA-PET and mpMRI showed the highest detection rate, suggesting an added value of a hybrid imaging approach.
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| 5. |
- Sandgren, Kristina, et al.
(author)
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Registration of histopathology to magnetic resonance imaging of prostate cancer
- 2021
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In: Physics and Imaging in Radiation Oncology. - : Elsevier. - 2405-6316. ; 18, s. 19-25
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Journal article (peer-reviewed)abstract
- Background and purpose: The diagnostic accuracy of new imaging techniques requires validation, preferably by histopathological verification. The aim of this study was to develop and present a registration procedure between histopathology and in-vivo magnetic resonance imaging (MRI) of the prostate, to estimate its uncertainty and to evaluate the benefit of adding a contour-correcting registration.Materials and methods: For twenty-five prostate cancer patients, planned for radical prostatectomy, a 3D-printed prostate mold based on in-vivo MRI was created and an ex-vivo MRI of the specimen, placed inside the mold, was performed. Each histopathology slice was registered to its corresponding ex-vivo MRI slice using a 2D-affine registration. The ex-vivo MRI was rigidly registered to the in-vivo MRI and the resulting transform was applied to the histopathology stack. A 2D deformable registration was used to correct for specimen distortion concerning the specimen's fit inside the mold. We estimated the spatial uncertainty by comparing positions of landmarks in the in-vivo MRI and the corresponding registered histopathology stack.Results: Eighty-four landmarks were identified, located in the urethra (62%), prostatic cysts (33%), and the ejaculatory ducts (5%). The median number of landmarks was 3 per patient. We showed a median in-plane error of 1.8 mm before and 1.7 mm after the contour-correcting deformable registration. In patients with extraprostatic margins, the median in-plane error improved from 2.1 mm to 1.8 mm after the contour-correcting deformable registration.Conclusions: Our registration procedure accurately registers histopathology to in-vivo MRI, with low uncertainty. The contour-correcting registration was beneficial in patients with extraprostatic surgical margins.
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| 6. |
- Zarei, Maryam, et al.
(author)
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Accuracy of gross tumour volume delineation with [68Ga]-PSMA-PET compared to histopathology for high-risk prostate cancer
- 2024
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In: Acta Oncologica. - : MJS Publishing, Medical Journals Sweden. - 0284-186X .- 1651-226X. ; 63, s. 503-510
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Journal article (peer-reviewed)abstract
- BACKGROUND: The delineation of intraprostatic lesions is vital for correct delivery of focal radiotherapy boost in patients with prostate cancer (PC). Errors in the delineation could translate into reduced tumour control and potentially increase the side effects. The purpose of this study is to compare PET-based delineation methods with histopathology.MATERIALS AND METHODS: The study population consisted of 15 patients with confirmed high-risk PC intended for prostatectomy. [68Ga]-PSMA-PET/MR was performed prior to surgery. Prostate lesions identified in histopathology were transferred to the in vivo [68Ga]-PSMA-PET/MR coordinate system. Four radiation oncologists manually delineated intraprostatic lesions based on PET data. Various semi-automatic segmentation methods were employed, including absolute and relative thresholds, adaptive threshold, and multi-level Otsu threshold.RESULTS: The gross tumour volumes (GTVs) delineated by the oncologists showed a moderate level of interobserver agreement with Dice similarity coefficient (DSC) of 0.68. In comparison with histopathology, manual delineations exhibited the highest median DSC and the lowest false discovery rate (FDR) among all approaches. Among semi-automatic approaches, GTVs generated using standardized uptake value (SUV) thresholds above 4 (SUV > 4) demonstrated the highest median DSC (0.41), with 0.51 median lesion coverage ratio, FDR of 0.66 and the 95th percentile of the Hausdorff distance (HD95%) of 8.22 mm.INTERPRETATION: Manual delineations showed a moderate level of interobserver agreement. Compared to histopathology, manual delineations and SUV > 4 exhibited the highest DSC and the lowest HD95% values. The methods that resulted in a high lesion coverage were associated with a large overestimation of the size of the lesions.
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| 7. |
- Adjeiwaah, Mary, 1980-, et al.
(author)
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Dosimetric Impact of MRI Distortions : A Study on Head and Neck Cancers
- 2019
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In: International Journal of Radiation Oncology, Biology, Physics. - : Elsevier. - 0360-3016 .- 1879-355X. ; 103:4, s. 994-1003
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Journal article (peer-reviewed)abstract
- Purpose: To evaluate the effect of magnetic resonance (MR) imaging (MRI) geometric distortions on head and neck radiation therapy treatment planning (RTP) for an MRI-only RTP. We also assessed the potential benefits of patient-specific shimming to reduce the magnitude of MR distortions for a 3-T scanner.Methods and Materials: Using an in-house Matlab algorithm, shimming within entire imaging volumes and user-defined regions of interest were simulated. We deformed 21 patient computed tomography (CT) images with MR distortion fields (gradient nonlinearity and patient-induced susceptibility effects) to create distorted CT (dCT) images using bandwidths of 122 and 488 Hz/mm at 3 T. Field parameters from volumetric modulated arc therapy plans initially optimized on dCT data sets were transferred to CT data to compute a new plan. Both plans were compared to determine the impact of distortions on dose distributions.Results: Shimming across entire patient volumes decreased the percentage of voxels with distortions of more than 2 mm from 15.4% to 2.0%. Using the user-defined region of interest (ROI) shimming strategy, (here the Planning target volume (PTV) was the chosen ROI volume) led to increased geometric for volumes outside the PTV, as such voxels within the spinal cord with geometric shifts above 2 mm increased from 11.5% to 32.3%. The worst phantom-measured residual system distortions after 3-dimensional gradient nonlinearity correction within a radial distance of 200 mm from the isocenter was 2.17 mm. For all patients, voxels with distortion shifts of more than 2 mm resulting from patient-induced susceptibility effects were 15.4% and 0.0% using bandwidths of 122 Hz/mm and 488 Hz/mm at 3 T. Dose differences between dCT and CT treatment plans in D-50 at the planning target volume were 0.4% +/- 0.6% and 0.3% +/- 0.5% at 122 and 488 Hz/mm, respectively.Conclusions: The overall effect of MRI geometric distortions on data used for RTP was minimal. Shimming over entire imaging volumes decreased distortions, but user-defined subvolume shimming introduced significant errors in nearby organs and should probably be avoided.
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| 8. |
- Adjeiwaah, Mary, 1980-
(author)
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Quality assurance for magnetic resonance imaging (MRI) in radiotherapy
- 2019
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Doctoral thesis (other academic/artistic)abstract
- The use of Magnetic Resonance Imaging (MRI) in the radiotherapy (RT) treatment planning workflow is increasing. MRI offers superior soft-tissue contrast compared to Computed Tomography (CT) and therefore improves the accuracy in target volume definitions. There are, however concerns with inherent geometric distortions from system- (gradient nonlinearities and main magnetic field inhomogeneities) and patient-related sources (magnetic susceptibility effect and chemical shift). The lack of clearly defined quality assurance (QA) procedures has also raised questions on the ability of current QA protocols to detect common image quality degradations under radiotherapy settings. To fully implement and take advantage of the benefits of MRI in radiotherapy, these concerns need to be addressed.In Papers I and II, the dosimetric impact of MR distortions was investigated. Patient CTs (CT) were deformed with MR distortion vector fields (from the residual system distortions after correcting for gradient nonlinearities and patient-induced susceptibility distortions) to create distorted CT (dCT) images. Field parameters from volumetric modulated arc therapy (VMAT) treatment plans initially optimized on dCT data sets were transferred to CT data to compute new treatment plans. Data from 19 prostate and 21 head and neck patients were used for the treatment planning. The dCT and CT treatment plans were compared to determine the impact of distortions on dose distributions. No clinically relevant dose differences between distorted CT and original CT treatment plans were found. Mean dose differences were < 1.0% and < 0.5% at the planning target volume (PTV) for the head and neck, and prostate treatment plans, respectively. Strategies to reduce geometric distortions were also evaluated in Papers I and II. Using the vendor-supplied gradient non-linearity correction algorithm reduced overall distortions to less than half of the original value. A high acquisition bandwidth of 488 Hz/pixel (Paper I) and 488 Hz/mm (Paper II) kept the mean geometric distortions at the delineated structures below 1 mm. Furthermore, a patient-specific active shimming method implemented in Paper II significantly reduced the number of voxels with distortion shifts > 2 mm from 15.4% to 2.0%.B0 maps from patient-induced magnetic field inhomogeneities obtained through direct measurements and by simulations that used MR-generated synthetic CT (sCT) data were compared in Paper III. The validation showed excellent agreement between the simulated and measured B0 maps.In Paper IV, the ability of current QA methods to detect common MR image quality degradations under radiotherapy settings were investigated. By evaluating key image quality parameters, the QA protocols were found to be sensitive to some of the introduced degradations. However, image quality issues such as those caused by RF coil failures could not be adequately detected.In conclusion, this work has shown the feasibility of using MRI data for radiotherapy treatment planning as distortions resulted in a dose difference of less than 1% between distorted and undistorted images. The simulation software can be used to produce accurate B0 maps, which could then be used as the basis for the effective correction of patient-induced field inhomogeneity distortions and for the QA verification of sCT data. Furthermore, the analysis of the strengths and weaknesses in current QA tools for MRI in RT contribute to finding better methods to efficiently identify image quality errors.
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| 9. |
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| 10. |
- Adjeiwaah, Mary, 1980-, et al.
(author)
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Sensitivity analysis of different quality assurance methods for magnetic resonance imaging in radiotherapy
- 2020
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In: Physics and Imaging in Radiation Oncology. - : Elsevier. - 2405-6316. ; 13, s. 21-27
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Journal article (peer-reviewed)abstract
- Background and purpose: There are currently no standard quality assurance (QA) methods for magnetic resonance imaging (MRI) in radiotherapy (RT). This work was aimed at evaluating the ability of two QA protocols to detect common events that affect quality of MR images under RT settings.Materials and methods: The American College of Radiology (ACR) MRI QA phantom was repeatedly scanned using a flexible coil and action limits for key image quality parameters were derived. Using an exploratory survey, issues that reduce MR image quality were identified. The most commonly occurring events were introduced as provocations to produce MR images with degraded quality. From these images, detection sensitivities of the ACR MRI QA protocol and a commercial geometric accuracy phantom were determined.Results: Machine-specific action limits for key image quality parameters set at mean±3σ" role="presentation" style="box-sizing: border-box; margin: 0px; padding: 0px; display: inline-block; line-height: normal; font-size: 16.2px; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;">mean±3σ were comparable with the ACR acceptable values. For the geometric accuracy phantom, provocations from uncorrected gradient nonlinearity effects and a piece of metal in the bore of the scanner resulted in worst distortions of 22.2 mm and 3.4 mm, respectively. The ACR phantom was sensitive to uncorrected signal variations, electric interference and a piece of metal in the bore of the scanner but could not adequately detect individual coil element failures.Conclusions: The ACR MRI QA phantom combined with the large field-of-view commercial geometric accuracy phantom were generally sensitive in identifying some common MR image quality issues. The two protocols when combined may provide a tool to monitor the performance of MRI systems in the radiotherapy environment.
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| 11. |
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| 12. |
- Appelgren, Patrik, et al.
(author)
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Modeling of a small helical magnetic flux compression generator
- 2008
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In: IEEE Transactions on Plasma Science. - 0093-3813 .- 1939-9375. ; 36:5, s. 2662-2672
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Journal article (peer-reviewed)abstract
- In order to gain experience in explosive pulsed power and to provide experimental data as the basis for computer modeling, a small high-explosive-driven helical magnetic flux-compression generator (FCG) was designed at the Swedish Defence Research Agency. The generator, of which three have been built, has an overall length of 300 mm and a diameter of 70 mm. It could serve as the energy source in a pulse-forming network to generate high-power pulses for various loads. This paper presents a simulation model of this helical FCG. The model, which was implemented in Matlab-Simulink, uses analytical expressions for the generator inductance. The model of resistive losses takes into account the heating of the conductors and the diffusion of the magnetic field into the conductors. The simulation results are compared with experimental data from two experiments with identical generators but with different seed currents, influencing the resistive losses. The model is used to analyze the performance of the generator.
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| 13. |
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| 14. |
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| 15. |
- Appelgren, Patrik, et al.
(author)
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Small helical magnetic flux compression generators : Experiments and analysis
- 2007
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In: PPPS-2007 - Pulsed Power Plasma Science 2007. - : IEEE. - 1424409144 - 9781424409143 ; , s. 1151-1154
-
Conference paper (peer-reviewed)abstract
- This paper presents experimental results with helical magnetic flux-compression generators (FCGs). FCGs convert the chemical energy bond in explosives into electric energy. The generator had an initial inductance of 23 μH and was operated into a load of 0.2 μH. The generator is charged with 0.27 kg of high-explosives (PBXN-5). Various types of diagnostics were used to monitor the operation of the generator, including current probes, optical fibres, and piezo gauges. The results are analysed and the expansion of the armature compared with hydrodynamic simulations.
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| 16. |
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| 17. |
- Appelgren, Patrik, et al.
(author)
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Small Helical Magnetic Flux-Compression Generators : Experiments and Analysis
- 2008
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In: IEEE Transactions on Plasma Science. - 0093-3813 .- 1939-9375. ; 36:5, s. 2673-2683
-
Journal article (peer-reviewed)abstract
- In order to gain experience in explosive pulsed power and to provide experimental data for modeling, a small high-explosive-driven helical magnetic flux-compression generator (FCG) was designed at the Swedish Defence Research Agency (FOI). The generator, of which three have been built, has an overall length of 300 mm and a diameter of 70 mm. It could serve as the energy source in a pulse-forming network to generate high power pulses for various loads. This paper presents the design of, and tests with, this helical FCG. The generator had an initial inductance of 23 mu H and was operated into a load of 0.2 mu H. The generator is charged with 0.27 kg of high explosives (PBXN-5). Various types of diagnostics were used to monitor the operation of the generator, including current probes, optical fibers, and piezo gauges. With seed currents of 5.7 and 11.2 kA, final currents of 269 and 436 kA were obtained, corresponding to current amplification factors of 47 and 39. The peak of the current was reached about 30 mu s after the time of crowbar. The two generators showed only small losses in terms of 2 pi-clocking. Using signals from optical fibers, the deflection angle of the armature could be determined to be 10 degrees in good agreement with hydrodynamic simulations of the detonation process and the detonation velocity to be 8.7 km/s in agreement with tabulated value.
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| 18. |
- Arcavi, Iair, et al.
(author)
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Energetic eruptions leading to a peculiar hydrogen-rich explosion of a massive star
- 2017
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 551:7679, s. 210-213
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Journal article (peer-reviewed)abstract
- Every supernova so far observed has been considered to be the terminal explosion of a star. Moreover, all supernovae with absorption lines in their spectra show those lines decreasing in velocity over time, as the ejecta expand and thin, revealing slower-moving material that was previously hidden. In addition, every supernova that exhibits the absorption lines of hydrogen has one main light-curve peak, or a plateau in luminosity, lasting approximately 100 days before declining(1). Here we report observations of iPTF14hls, an event that has spectra identical to a hydrogen-rich core-collapse supernova, but characteristics that differ extensively from those of known supernovae. The light curve has at least five peaks and remains bright for more than 600 days; the absorption lines show little to no decrease in velocity; and the radius of the line-forming region is more than an order of magnitude bigger than the radius of the photosphere derived from the continuum emission. These characteristics are consistent with a shell of several tens of solar masses ejected by the progenitor star at supernova-level energies a few hundred days before a terminal explosion. Another possible eruption was recorded at the same position in 1954. Multiple energetic pre-supernova eruptions are expected to occur in stars of 95 to 130 solar masses, which experience the pulsational pair instability(2-5). That model, however, does not account for the continued presence of hydrogen, or the energetics observed here. Another mechanism for the violent ejection of mass in massive stars may be required.
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| 19. |
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| 20. |
- Beldowski, Jacek, et al.
(author)
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Chemical Munitions Search & Assessment-An evaluation of the dumped munitions problem in the Baltic Sea
- 2016
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In: Deep-sea research. Part II, Topical studies in oceanography. - : Elsevier BV. - 0967-0645 .- 1879-0100. ; 128, s. 85-95
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Journal article (peer-reviewed)abstract
- Chemical Munitions Search & Assessment (CHEMSEA) project has performed studies on chemical weapon (CW) detection, sediment pollution and spreading as well as biological effects of chemical warfare agents (CWAs) dumped in the Baltic Sea. Results suggest that munitions containing CWAs are more scattered on the seafloor than suspected, and previously undocumented dumpsite was discovered in Gdansk Deep. Pollution of sediments with CWA degradation products was local and close to the detected objects; however the pollution range was larger than predicted with theoretical models. Bottom currents observed in the dumpsites were strong enough for sediment re-suspension, and contributed to the transport of polluted sediments. Diversity and density of the faunal communities were poor at the dumping sites in comparison to the reference area, although the direct effects of CWA on benthos organisms were difficult to determine due to hypoxic or even anoxic conditions near the bottom. Equally, the low oxygen might have affected the biological effects assessed in cod and caged blue mussels. Nonetheless, both species showed significantly elevated molecular and cellular level responses at contaminated sites compared to reference sites.
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| 21. |
- Bergquist, Filip, 1970, et al.
(author)
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Parkinson's disease - heterogeneous and complex in its clinical presentation.
- 2020
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In: Läkartidningen. - 0023-7205 .- 1652-7518. ; 117
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Journal article (peer-reviewed)abstract
- Parkinson's disease is the second most common neurodegenerative disease. Lewy bodies with alpha-synuclein as the major component and loss of dopaminergic nerve cells in substantia nigra are neuropathological features. The diagnosis of Parkinson's disease is based on the occurrence of bradykinesia, rigidity and resting tremor. The disease is also associated with several non-motor symptoms. The therapy is mainly based on pharmacological treatment to increase dopamine signaling and neurosurgical deep brain stimulation. The symptoms and signs of the progressive disease change over time, requiring treatment adjustments. Patients should be followed by a physician, nurse and a multidisciplinary team with expertise in Parkinson's disease.
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| 22. |
- Bergquist, Filip, et al.
(author)
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Parkinsons sjukdom – heterogen och komplex i sitt kliniska uttryck - Individuella kombinationer av symtom som ändrar sig över tid kräver behandlingsjusteringar och anpassningar
- 2020
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In: Läkartidningen. - 0023-7205. ; 117
-
Journal article (peer-reviewed)abstract
- Parkinson's disease is the second most common neurodegenerative disease. Lewy bodies with alpha-synuclein as the major component and loss of dopaminergic nerve cells in substantia nigra are neuropathological features. The diagnosis of Parkinson's disease is based on the occurrence of bradykinesia, rigidity and resting tremor. The disease is also associated with several non-motor symptoms. The therapy is mainly based on pharmacological treatment to increase dopamine signaling and neurosurgical deep brain stimulation. The symptoms and signs of the progressive disease change over time, requiring treatment adjustments. Patients should be followed by a physician, nurse and a multidisciplinary team with expertise in Parkinson's disease.
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| 23. |
- Bergquist, Filip, et al.
(author)
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Parkinsons sjukdom [Parkinsons disease] : heterogen och komplex i sitt kliniska uttryck [heterogeneous and complex in its clinical presentation]
- 2020
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In: Läkartidningen. - : Sveriges Läkarförbund. - 0023-7205 .- 1652-7518. ; 117
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Journal article (peer-reviewed)abstract
- Parkinsons disease is the second most common neurodegenerative disease. Lewy bodies with alpha-synuclein as the major component and loss of dopaminergic nerve cells in substantia nigra are neuropathological features. The diagnosis of Parkinsons disease is based on the occurrence of bradykinesia, rigidity and resting tremor. The disease is also associated with several non-motor symptoms. The therapy is mainly based on pharmacological treatment to increase dopamine signaling and neurosurgical deep brain stimulation. The symptoms and signs of the progressive disease change over time, requiring treatment adjustments. Patients should be followed by a physician, nurse and a multidisciplinary team with expertise in Parkinsons disease.
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| 24. |
- Bergquist, Filip, et al.
(author)
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Pharmacokinetics of Intravenously (DIZ101), Subcutaneously (DIZ102), and Intestinally (LCIG) Infused Levodopa in Advanced Parkinson Disease
- 2022
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In: Neurology. - : Lippincott, Williams & Wilkins. - 0028-3878 .- 1526-632X. ; 99:10, s. E965-E976
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Journal article (peer-reviewed)abstract
- Background and Objectives Intestinal levodopa/carbidopa gel infusion (LCIG) is superior to oral treatment in advanced Parkinson disease. The primary objective of this trial was to investigate whether continuous subcutaneous or intravenous infusion with a continuously buffered acidic levodopa/carbidopa solution yields steady-state plasma concentrations of levodopa that are equivalent in magnitude, and noninferior in variability, to those obtained with LCIG in patients with advanced Parkinson disease. Methods A concentrated acidic levodopa/carbidopa (8:1) solution buffered continuously and administered intravenously (DIZ101) or subcutaneously (DIZ102) was compared with an approved LCIG in a randomized, 3-period crossover, open-label, multicenter trial. Formulations were infused for 16 hours to patients with Parkinson disease who were using LCIG as their regular treatment. Patients were recruited from several university neurology clinics but came to the same phase I unit for treatment. Pharmacokinetic variables and safety including dermal tolerance are reported. The primary outcomes were bioequivalence and noninferior variability of DIZ101 and DIZ102 vs LCIG with respect to levodopa plasma concentrations. Results With dosing adjusted to estimated bioavailability, DIZ101 and DIZ102 produced levodopa plasma levels within standard bioequivalence limits compared with LCIG in the 18 participants who received all treatments. Although the levodopa bioavailability for DIZ102 was complete, it was 80% for LCIG. Therapeutic concentrations of levodopa were reached as quickly with subcutaneous administration of DIZ102 as with LCIG and remained stable throughout the infusions. Owing to poor uptake of LCIG, carbidopa levels in plasma were higher with DIZ101 and DIZ102 than with the former. All individuals receiving any of the treatments (n = 20) were included in the evaluation of safety and tolerability. Reactions at the infusion sites were mild and transient. Discussion It is feasible to rapidly achieve high and stable levodopa concentrations by means of continuous buffering of a subcutaneously administered acidic levodopa/carbidopa-containing solution.
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| 25. |
- Björeland, Ulrika, et al.
(author)
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Hyaluronic acid spacer in prostate cancer radiotherapy : dosimetric effects, spacer stability and long-term toxicity and PRO in a phase II study
- 2023
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In: Radiation Oncology. - : BioMed Central (BMC). - 1748-717X. ; 18:1
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Journal article (peer-reviewed)abstract
- BACKGROUND: Perirectal spacers may be beneficial to reduce rectal side effects from radiotherapy (RT). Here, we present the impact of a hyaluronic acid (HA) perirectal spacer on rectal dose as well as spacer stability, long-term gastrointestinal (GI) and genitourinary (GU) toxicity and patient-reported outcome (PRO).METHODS: In this phase II study 81 patients with low- and intermediate-risk prostate cancer received transrectal injections with HA before external beam RT (78 Gy in 39 fractions). The HA spacer was evaluated with MRI four times; before (MR0) and after HA-injection (MR1), at the middle (MR2) and at the end (MR3) of RT. GI and GU toxicity was assessed by physician for up to five years according to the RTOG scale. PROs were collected using the Swedish National Prostate Cancer Registry and Prostate cancer symptom scale questionnaires.RESULTS: There was a significant reduction in rectal V70% (54.6 Gy) and V90% (70.2 Gy) between MR0 and MR1, as well as between MR0 to MR2 and MR3. From MR1 to MR2/MR3, HA thickness decreased with 28%/32% and CTV-rectum space with 19%/17% in the middle level. The cumulative late grade ≥ 2 GI toxicity at 5 years was 5% and the proportion of PRO moderate or severe overall bowel problems at 5 years follow-up was 12%. Cumulative late grade ≥ 2 GU toxicity at 5 years was 12% and moderate or severe overall urinary problems at 5 years were 10%.CONCLUSION: We show that the HA spacer reduced rectal dose and long-term toxicity.
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| 26. |
- Borg, Mikael, et al.
(author)
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Experimental and theoretical surface core-level shifts of aluminum (100) and (111)
- 2004
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In: Physical Review B. - 1550-235X. ; 69
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Journal article (peer-reviewed)abstract
- The surface core-level shifts of Al(111) and Al(100) have been measured using high-resolution core-level photoemission spectroscopy and calculated using density functional theory (DFT). For Al(100), the 2p core-level shift of the first (second) layer was determined to be –75 meV (+20 meV) from experiment and –71 meV (+20 meV) from the DFT calculations. For Al(111), the corresponding values are –27 meV (0 meV) from experiment and –14 meV (–) from the DFT calculations. Core-level splittings caused by the low-symmetry crystal fields at the (111) and (100) surfaces have also been studied. These splittings turn out to be much smaller than previously reported provided proper care is taken of the influence of the core hole screening and of core–valence exchange beyond the DFT level. Finally, the experimental Al 2p line shape was found to contain structure caused by a sharp no-phonon line and a broad and weak phonon replica.
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| 27. |
- Both, C., et al.
(author)
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Large-scale geographical variation confirms that climate change causes birds to lay earlier
- 2004
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In: Proceedings of the Royal Society of London Series B-Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 271:1549, s. 1657-1662
-
Journal article (peer-reviewed)abstract
- Advances in the phenology of organisms are often attributed to climate change, but alternatively, may reflect a publication bias towards advances and may be caused by environmental factors unrelated to climate change. Both factors are investigated using the breeding dates of 25 long-term studied populations of Ficedula flycatchers across Europe. Trends in spring temperature varied markedly between study sites, and across populations the advancement of laying date was stronger in areas where the spring temperatures increased more, giving support to the theory that climate change causally affects breeding date advancement.
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| 28. |
- Both, C., et al.
(author)
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Pied Flycatchers Ficedula hypoleuca travelling from Africa to breed in Europe: differential effects of winter and migration conditions on breeding date
- 2006
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In: ARDEA. - 0373-2266 .- 2213-1175. ; 94:3, s. 511-525
-
Journal article (peer-reviewed)abstract
- In most bird species there is only a short time window available for optimal breeding due to variation in ecological conditions in a seasonal environment. Long-distance migrants must travel before they start breeding, and conditions at the wintering grounds and during migration may affect travelling speed and hence arrival and breeding dates. These effects are to a large extent determined by climate variables such as rainfall and temperature, and need to be identified to predict how well species can adapt to climate change. In this paper we analyse effects of vegetation growth on the wintering grounds and sites en route on the annual timing of breeding of 17 populations of Pied Flycatchers Ficedula hypoleuca studied between 1982–2000. Timing of breeding was largely correlated with local spring temperatures, supplemented by striking effects of African vegetation and NAO. Populations differed in the effects of vegetation growth on the wintering grounds, and on their northern African staging grounds, as well as ecological conditions in Europe as measured by the winter NAO. In general, early breeding populations (low altitude, western European populations) bred earlier in years with more vegetation in the Northern Sahel zone, as well as in Northern Africa. In contrast, late breeding populations (high altitude and northern and eastern populations) advanced their breeding dates when circumstances in Europe were more advanced (high NAO). Thus, timing of breeding in most Pied Flycatcher populations not only depends upon local circumstances, but also on conditions encountered during travelling, and these effects differ across populations dependent on the timing of travelling and breeding.
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| 29. |
- Brennan, S. J., et al.
(author)
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Photometric and spectroscopic evolution of the interacting transient AT 2016jbu(Gaia16cfr)
- 2022
-
In: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 513:4, s. 5642-5665
-
Journal article (peer-reviewed)abstract
- We present the results from a high-cadence, multiwavelength observation campaign of AT 2016jbu (aka Gaia16cfr), an interacting transient. This data set complements the current literature by adding higher cadence as well as extended coverage of the light-curve evolution and late-time spectroscopic evolution. Photometric coverage reveals that AT 2016jbu underwent significant photometric variability followed by two luminous events, the latter of which reached an absolute magnitude of MV ∼ −18.5 mag. This is similar to the transient SN 2009ip whose nature is still debated. Spectra are dominated by narrow emission lines and show a blue continuum during the peak of the second event. AT 2016jbu shows signatures of a complex, non-homogeneous circumstellar material (CSM). We see slowly evolving asymmetric hydrogen line profiles, with velocities of 500 km s−1 seen in narrow emission features from a slow-moving CSM, and up to 10 000 km s−1 seen in broad absorption from some high-velocity material. Late-time spectra (∼+1 yr) show a lack of forbidden emission lines expected from a core-collapse supernova and are dominated by strong emission from H, He I, and Ca II. Strong asymmetric emission features, a bumpy light curve, and continually evolving spectra suggest an inhibit nebular phase. We compare the evolution of H α among SN 2009ip-like transients and find possible evidence for orientation angle effects. The light-curve evolution of AT 2016jbu suggests similar, but not identical, circumstellar environments to other SN 2009ip-like transients.
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| 30. |
- Brynolfsson, Patrik, et al.
(author)
-
ADC texture-An imaging biomarker for high-grade glioma?
- 2014
-
In: Medical physics (Lancaster). - : Wiley. - 0094-2405. ; 41:10, s. 101903-
-
Journal article (peer-reviewed)abstract
- Purpose:Survival for high-grade gliomas is poor, at least partly explained by intratumoral heterogeneity contributing to treatment resistance. Radiological evaluation of treatment response is in most cases limited to assessment of tumor size months after the initiation of therapy. Diffusion-weighted magnetic resonance imaging (MRI) and its estimate of the apparent diffusion coefficient (ADC) has been widely investigated, as it reflects tumor cellularity and proliferation. The aim of this study was to investigate texture analysis of ADC images in conjunction with multivariate image analysis as a means for identification of pretreatment imaging biomarkers.Methods:Twenty-three consecutive high-grade glioma patients were treated with radiotherapy (2 Gy/60 Gy) with concomitant and adjuvant temozolomide. ADC maps and T1-weighted anatomical images with and without contrast enhancement were collected prior to treatment, and (residual) tumor contrast enhancement was delineated. A gray-level co-occurrence matrix analysis was performed on the ADC maps in a cuboid encapsulating the tumor in coronal, sagittal, and transversal planes, giving a total of 60 textural descriptors for each tumor. In addition, similar examinations and analyses were performed at day 1, week 2, and week 6 into treatment. Principal component analysis (PCA) was applied to reduce dimensionality of the data, and the five largest components (scores) were used in subsequent analyses. MRI assessment three months after completion of radiochemotherapy was used for classifying tumor progression or regression.Results:The score scatter plots revealed that the first, third, and fifth components of the pretreatment examinations exhibited a pattern that strongly correlated to survival. Two groups could be identified: one with a median survival after diagnosis of 1099 days and one with 345 days, p = 0.0001.Conclusions:By combining PCA and texture analysis, ADC texture characteristics were identified, which seems to hold pretreatment prognostic information, independent of known prognostic factors such as age, stage, and surgical procedure. These findings encourage further studies with a larger patient cohort. (C) 2014 Author(s).
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| 31. |
- Brynolfsson, Patrik, 1981-
(author)
-
Applications of statistical methods in quantitative magnetic resonance imaging
- 2017
-
Doctoral thesis (other academic/artistic)abstract
- Magnetic resonance imaging, MRI, offers a vast range of imaging methods that can be employed in the characterization of tumors. MRI is generally used in a qualitative way, where radiologists interpret the images for e.g. diagnosis, follow ups, or assessment of treatment response. In the past decade, there has been an increasing interest for quantitative imaging, which give repeatable measurements of the anatomy. Quantitative imaging allows for objective analysis of the images, which are grounded in physical properties of the underlying tissues. The aim of this thesis was to improve quantitative measurements of Dynamic contrast enhanced MRI (DCE-MRI), and the texture analysis of diffusion weighted MRI (DW-MRI).DCE-MRI measures perfusion, which is the delivery of blood, oxygen and nutrients to the tissues. The exam involves continuously imaging the region of interest, e.g. a tumor, while injecting a contrast agent (CA) in the blood stream. By analyzing how fast and how much CA leaks out into the tissues, the cell density and the permeability of the capillaries can be estimated. Tumors often have an irregular and broken vasculature, and DCE-MRI can aid in tumor grading or treatment assessment. One step is crucial when performing DCE-MRI analysis, the quantification of CA in the tissue. The CA concentration is difficult to measure accurately due to uncertainties in the imaging, properties of the CA, and physiology of the patient. Paper I, the possibility of using two aspects of the MRI data, phase and magnitude, for improved CA quantification, is explored. We found that the combination of phase and magnitude information improved the CA quantification in regions with high CA concentration, and was more advantageous for high field strength scanners.DW-MRI measures the diffusion of water in and between cells, which reflects the cell density and structure of the tissue. The structure of a tumor can give insights into the prognosis of the disease. Tumors are heterogeneous, both genetically and in the distribution of cells, and tumors with high intratumoral heterogeneity have poorer prognosis. This heterogeneity can be measured using texture analysis. In 1973, Haralick et al. presented a texture analysis method using a gray level co-occurrence matrix, GLCM, to gauge the spatial distribution of gray levels in the image. This method of assessing texture in images has been successfully applied in many areas of research, from satellite images to medical applications. Texture analysis in treatment outcome assessment is studied in Paper II, where we showed that texture can distinguish between groups of patients with different survival times, in images acquired prior to treatment start.However, this type of texture analysis is not inherently quantitative in the way it is calculated today. This was studied in Paper III, where we investigated how texture features were affected by five parameters related to image acquisition and pre-processing. We found that the texture feature values were dependent on the choice of these imaging and preprocessing parameters. In Paper IV, a novel method for calculating Haralick texture features was presented, which makes the texture features asymptotically invariant to the size of the GLCM. This method allows for comparison of textures between images that have been analyzed in different ways.In conclusion, the work in this thesis has been aimed at improving quantitative analysis of tumors using MRI and texture analysis.
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| 32. |
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| 33. |
- Brynolfsson, Patrik, et al.
(author)
-
Haralick texture features from apparent diffusion coefficient (ADC) MRI images depend on imaging and pre-processing parameters
- 2017
-
In: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 7
-
Journal article (peer-reviewed)abstract
- In recent years, texture analysis of medical images has become increasingly popular in studies investigating diagnosis, classification and treatment response assessment of cancerous disease. Despite numerous applications in oncology and medical imaging in general, there is no consensus regarding texture analysis workflow, or reporting of parameter settings crucial for replication of results. The aim of this study was to assess how sensitive Haralick texture features of apparent diffusion coefficient (ADC) MR images are to changes in five parameters related to image acquisition and pre-processing: noise, resolution, how the ADC map is constructed, the choice of quantization method, and the number of gray levels in the quantized image. We found that noise, resolution, choice of quantization method and the number of gray levels in the quantized images had a significant influence on most texture features, and that the effect size varied between different features. Different methods for constructing the ADC maps did not have an impact on any texture feature. Based on our results, we recommend using images with similar resolutions and noise levels, using one quantization method, and the same number of gray levels in all quantized images, to make meaningful comparisons of texture feature results between different subjects.
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| 34. |
- Busk, Karin, et al.
(author)
-
Long-term efficacy and safety with continuous dopaminergic stimulation pump treatments in Parkinson's disease
- 2011
-
In: European Neurological Review. - 1758-3837. ; 6:3, s. 156-160
-
Journal article (peer-reviewed)abstract
- Continuous dopaminergic stimulation (CDS) is important for symptom control in advanced stages of Parkinson’s disease (PD). The most efficacious approaches are pump treatments with dopaminergic drugs: subcutaneous infusion of the dopamine receptor agonist apomorphine and intestinal infusion of levodopa/carbidopa gel. Both methods decrease motor fluctuations in long-term follow-ups, including parkinsonian and dyskinetic states, when compared to conventional optimised oral therapy. Also non-motor symptoms may be improved. Adverse drug reactions are usually less pronounced although high levodopa doses, which are common with levodopa/carbidopa infusion, may cause hyperhomocysteinaemia and cobalamin deficiency. Technical complications are specific for each infusion strategy. Formation of subcutaneous nodules is the most common problem with apomorphine infusion. Dislocation of the intestinal tube is the most common problem with levodopa/carbidopa infusion. Both pump treatments may be used for 24-hour infusion in selected patients. The long-term experience is reviewed. To conclude, CDS pump treatments may be successfully used for several years in advanced PD.
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| 35. |
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| 36. |
- Cheah, Seng Kian, et al.
(author)
-
Self-Supported Three-Dimensional Nanoelectrodes for Microbattery Applications
- 2009
-
In: Nano letters (Print). - : American Chemical Society. - 1530-6984 .- 1530-6992. ; 9:9, s. 3230-3233
-
Journal article (peer-reviewed)abstract
- A nanostructured three-dimensional (3D) microbattery has been produced and cycled in a Li-ion battery. It consists of a current collector of aluminum nanorods, a uniform layer of 17 nm TiO2 covering the nanorods made using ALD, an electrolyte and metallic lithium counter electrode. The battery is electrochemically cycled more than 50 times. The increase in total capacity is 10 times when using a 3D architechture compared to a 2D system for the same footprint area.
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| 37. |
- Elfsberg, Mattias, et al.
(author)
-
Experimental Studies of Anode and Cathode Materials in a Repetitive Driven Axial Vircator
- 2008
-
In: IEEE Transactions on Plasma Science. - 0093-3813 .- 1939-9375. ; 36, s. 688-693
-
Journal article (peer-reviewed)abstract
- Repetitive use of a high-power microwave (HPM) radiation source implies strong erosion on cathode and anode materials. Electrode material endurance has been studied in a series of experiments with an axial vircator powered by a compact Marx generator. The Marx generator operated in a 10 Hz repetitive mode with a burst of ten pulses. Velvet and graphite was used as electron-emitting materials, and they showed markedly different pulse characteristics. Three different anode materials were used; stainless steel mesh, stainless steel wires and molybdenum wires, which all had different influence on the pulse characteristics.
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| 38. |
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| 39. |
- Fischerström, Ann, et al.
(author)
-
Acute neurosurgery for traumatic brain injury by general surgeons in Swedish county hospitals : A regional study
- 2014
-
In: Acta Neurochirurgica. - : Springer Science and Business Media LLC. - 0001-6268 .- 0942-0940. ; 156:1, s. 177-185
-
Journal article (peer-reviewed)abstract
- Traditionally acute life-saving evacuations of extracerebral haematomas are performed by general surgeons on vital indication in county hospitals in the Uppsala-A-rebro health care region in Sweden, a region characterized by long distances and a sparsely distributed population. Recently, it was stated in the guidelines for prehospital care of traumatic brain injury from the Scandinavian Neurosurgical Society that acute neurosurgery should not be performed in smaller hospitals without neurosurgical expertise. The aim of this study was to investigate: how often does acute decompressive neurosurgery occur in county hospitals in the Uppsala-A-rebro region today, what is the indication for surgery, and what is the clinical outcome? Finally, the goal was to evaluate whether the current practice in the Uppsala-A-rebro region should be revised. Patients referred to the neurointensive care unit at the Department of Neurosurgery in Uppsala after acute evacuation of intracranial haematomas in the county hospitals 2005-2010 were included in the study. Data was collected retrospectively from the medical records following a predefined protocol. The presence of vital indication, radiological and clinical results, and long-term outcome were evaluated. A total of 49 patients (17 epidural haematomas and 32 acute subdural haematomas) were included in the study. The operation was judged to have been performed on vital indication in all cases. The postoperative CT scan was improved in 92 % of the patients. The reaction level and pupillary reactions were significantly improved after surgery. Long-term outcomes showed 51 % favourable outcome, 33 % unfavourable outcome, and in 16 % the outcome was unknown. Looking at the indication for acute neurosurgery, the postoperative clinical and radiological results, and the long-term outcome, it appears that our regional policy regarding life-saving decompressive neurosurgery in county hospitals by general surgeons should not be changed. We suggest a curriculum aimed at educating general surgeons in acute neurosurgery.
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| 40. |
- Fransson, Samuel, et al.
(author)
-
Intrafractional motion models based on principal components in Magnetic Resonance guided prostate radiotherapy
- 2021
-
In: Physics and Imaging in Radiation Oncology. - : Elsevier. - 2405-6316. ; 20, s. 17-22
-
Journal article (peer-reviewed)abstract
- Background and purpose: Devices that combine an MR-scanner with a Linac for radiotherapy, referred to as MR-Linac systems, introduce the possibility to acquire high resolution images prior and during treatment. Hence, there is a possibility to acquire individualised learning sets for motion models for each fraction and the construction of intrafractional motion models. We investigated the feasibility for a principal component analysis (PCA) based, intrafractional motion model of the male pelvic region.Materials and methods: 4D-scans of nine healthy male volunteers were utilized, FOV covering the entire pelvic region including prostate, bladder and rectum with manual segmentation of each organ at each time frame. Deformable image registration with an optical flow algorithm was performed for each subject with the first time frame as reference. PCA was performed on a subset of the resulting displacement vector fields to construct individualised motion models evaluated on the remaining fields.Results: The registration algorithm produced accurate registration result, in general DICE overlap >0.95 across all time frames. Cumulative variance of the eigen values from the PCA showed that 50% or more of the motion is explained in the first component for all subjects. However, the size and direction for the components differed between subjects. Adding more than two components did not improve the accuracy significantly and the model was able to explain motion down to about 1 mm.onclusions: An individualised intrafractional male pelvic motion model is feasible. Geometric accuracy was about 1 mm based on 1-2 principal components.
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| 41. |
- Fremling, Christoffer, et al.
(author)
-
PTF12os and iPTF13bvn. Two stripped-envelope supernovae from low-mass progenitors in NGC 5806
- 2016
-
In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 593
-
Journal article (peer-reviewed)abstract
- Context. We investigate two stripped-envelope supernovae (SNe) discovered in the nearby galaxy NGC 5806 by the (intermediate) Palomar Transient Factory [(i)PTF]. These SNe, designated PTF12os/SN 2012P and iPTF13bvn, exploded within ~520 days of one another at a similar distance from the host-galaxy center. We classify PTF12os as a Type IIb SN based on our spectral sequence; iPTF13bvn has previously been classified as Type Ib having a likely progenitor with zero age main sequence (ZAMS) mass below ~17 M⊙. Because of the shared and nearby host, we are presented with a unique opportunity to compare these two SNe.Aims. Our main objective is to constrain the explosion parameters of iPTF12os and iPTF13bvn, and to put constraints on the SN progenitors. We also aim to spatially map the metallicity in the host galaxy, and to investigate the presence of hydrogen in early-time spectra of both SNe.Methods. We present comprehensive datasets collected on PTF12os and iPTF13bvn, and introduce a new automatic reference-subtraction photometry pipeline (FPipe) currently in use by the iPTF. We perform a detailed study of the light curves (LCs) and spectral evolution of the SNe. The bolometric LCs are modeled using the hydrodynamical code hyde. We analyze early spectra of both SNe to investigate the presence of hydrogen; for iPTF13bvn we also investigate the regions of the Paschen lines in infrared spectra. We perform spectral line analysis of helium and iron lines to map the ejecta structure of both SNe. We use nebular models and late-time spectroscopy to constrain the ZAMS mass of the progenitors. We also perform image registration of ground-based images of PTF12os to archival HST images of NGC 5806 to identify a potential progenitor candidate.Results. We find that our nebular spectroscopy of iPTF13bvn remains consistent with a low-mass progenitor, likely having a ZAMS mass of ~12M⊙. Our late-time spectroscopy of PTF12os is consistent with a ZAMS mass of ~15M⊙. We successfully identify a source in pre-explosion HST images coincident with PTF12os. The colors and absolute magnitude of this object are consistent between pre-explosion and late-time HST images, implying it is a cluster of massive stars. Our hydrodynamical modeling suggests that the progenitor of PTF12os had a compact He core with a mass of 3.25+ 0.77-0.56M⊙ at the time of the explosion, which had a total kinetic energy of 0.54+ 0.41-0.25 × 1051 erg and synthesized 0.063+ 0.020-0.011M⊙ of strongly mixed 56Ni. Spectral comparisons to the Type IIb SN 2011dh indicate that the progenitor of PTF12os was surrounded by a thin hydrogen envelope with a mass lower than 0.02M⊙. We also find tentative evidence that the progenitor of iPTF13bvn could have been surrounded by a small amount of hydrogen prior to the explosion. This result is supported by possible weak signals of hydrogen in both optical and infrared spectra.
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| 42. |
- Garpebring, Anders, et al.
(author)
-
Density Estimation of Grey-Level Co-Occurrence Matrices for Image Texture Analysis
- 2018
-
In: Physics in Medicine and Biology. - : Institute of Physics and Engineering in Medicine. - 0031-9155 .- 1361-6560. ; 63:19, s. 9-15
-
Journal article (peer-reviewed)abstract
- The Haralick texture features are common in the image analysis literature, partly because of their simplicity and because their values can be interpreted. It was recently observed that the Haralick texture features are very sensitive to the size of the GLCM that was used to compute them, which led to a new formulation that is invariant to the GLCM size. However, these new features still depend on the sample size used to compute the GLCM, i.e. the size of the input image region-of-interest (ROI).The purpose of this work was to investigate the performance of density estimation methods for approximating the GLCM and subsequently the corresponding invariant features.Three density estimation methods were evaluated, namely a piece-wise constant distribution, the Parzen-windows method, and the Gaussian mixture model. The methods were evaluated on 29 different image textures and 20 invariant Haralick texture features as well as a wide range of different ROI sizes.The results indicate that there are two types of features: those that have a clear minimum error for a particular GLCM size for each ROI size, and those whose error decreases monotonically with increased GLCM size. For the first type of features, the Gaussian mixture model gave the smallest errors, and in particular for small ROI sizes (less than about 20×20).In conclusion, the Gaussian mixture model is the preferred method for the first type of features (in particular for small ROIs). For the second type of features, simply using a large GLCM size is preferred.
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| 43. |
- Georg, Dietmar, et al.
(author)
-
Clinical evaluation of monitor unit software and the application of action levels
- 2007
-
In: Radiotherapy and Oncology. - : Elsevier BV. - 0167-8140 .- 1879-0887. ; 85:2, s. 306-315
-
Journal article (peer-reviewed)abstract
- PURPOSE: The aim of this study was the clinical evaluation of an independent dose and monitor unit verification (MUV) software which is based on sophisticated semi-analytical modelling. The software was developed within the framework of an ESTRO project. Finally, consistent handling of dose calculation deviations applying individual action levels is discussed. MATERIALS AND METHODS: A Matlab-based software ("MUV") was distributed to five well-established treatment centres in Europe (Vienna, Graz, Basel, Copenhagen, and Umeå) and evaluated as a quality assurance (QA) tool in clinical routine. Results were acquired for 226 individual treatment plans including a total of 815 radiation fields. About 150 beam verification measurements were performed for a portion of the individual treatment plans, mainly with time variable fluence patterns. The deviations between dose calculations performed with a treatment planning system (TPS) and the MUV software were scored with respect to treatment area, treatment technique, geometrical depth, radiological depth, etc. RESULTS: In general good agreement was found between calculations performed with the different TPSs and MUV, with a mean deviation per field of 0.2+/-3.5% (1 SD) and mean deviations of 0.2+/-2.2% for composite treatment plans. For pelvic treatments less than 10% of all fields showed deviations larger than 3%. In general, when using the radiological depth for verification calculations the results and the spread in the results improved significantly, especially for head-and-neck and for thorax treatments. For IMRT head-and-neck beams, mean deviations between MUV and the local TPS were -1.0+/-7.3% for dynamic, and -1.3+/-3.2% for step-and-shoot IMRT delivery. For dynamic IMRT beams in the pelvis good agreement was obtained between MUV and the local TPS (mean: -1.6+/-1.5%). Treatment site and treatment technique dependent action levels between +/-3% and +/-5% seem to be clinically realistic if a radiological depth correction is performed, even for dynamic wedges and IMRT. CONCLUSION: The software MUV is well suited for patient specific treatment plan QA applications and can handle all currently available treatment techniques that can be applied with standard linear accelerators. The highly sophisticated dose calculation model implemented in MUV allows investigation of systematic TPS deviations by performing calculations in homogeneous conditions
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| 44. |
- Georg, Dietmar, et al.
(author)
-
Patient-specific IMRT verification using independent fluence-based dose calculation software : experimental benchmarking and initial clinical experience
- 2007
-
In: Physics in Medicine and Biology. - : IOP Publishing. - 0031-9155 .- 1361-6560. ; 52:16, s. 4981-4992
-
Journal article (peer-reviewed)abstract
- Experimental methods are commonly used for patient-specific intensity-modulated radiotherapy (IMRT) verification. The purpose of this study was to investigate the accuracy and performance of independent dose calculation software ( denoted as 'MUV' ( monitor unit verification)) for patient-specific quality assurance (QA). 52 patients receiving step-and-shoot IMRT were considered. IMRT plans were recalculated by the treatment planning systems (TPS) in a dedicated QA phantom, in which an experimental 1D and 2D verification (0.3 cm(3) ionization chamber; films) was performed. Additionally, an independent dose calculation was performed. The fluence-based algorithm of MUV accounts for collimator transmission, rounded leaf ends, tongue-and-groove effect, backscatter to the monitor chamber and scatter from the flattening filter. The dose calculation utilizes a pencil beam model based on a beam quality index. DICOM RT files from patient plans, exported from the TPS, were directly used as patient-specific input data in MUV. For composite IMRT plans, average deviations in the high dose region between ionization chamber measurements and point dose calculations performed with the TPS and MUV were 1.6 +/- 1.2% and 0.5 +/- 1.1% ( 1 S. D.). The dose deviations between MUV and TPS slightly depended on the distance from the isocentre position. For individual intensity-modulated beams ( total 367), an average deviation of 1.1 +/- 2.9% was determined between calculations performed with the TPS and with MUV, with maximum deviations up to 14%. However, absolute dose deviations were mostly less than 3 cGy. Based on the current results, we aim to apply a confidence limit of 3% ( with respect to the prescribed dose) or 6 cGy for routine IMRT verification. For off-axis points at distances larger than 5 cm and for low dose regions, we consider 5% dose deviation or 10 cGy acceptable. The time needed for an independent calculation compares very favourably with the net time for an experimental approach. The physical effects modelled in the dose calculation software MUV allow accurate dose calculations in individual verification points. Independent calculations may be used to replace experimental dose verification once the IMRT programme is mature.
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| 45. |
- Gretarsdottir, Helga Maria, et al.
(author)
-
Personalized Medicine Approach in Treating Parkinson's Disease, Using Oral Administration of Levodopa/Carbidopa Microtablets in Clinical Practice
- 2021
-
In: Journal of Personalized Medicine. - : MDPI. - 2075-4426. ; 11:8
-
Journal article (peer-reviewed)abstract
- Background: The most effective symptomatic treatment in Parkinson's disease (PD) is levodopa in standard doses. However, as the disease progresses, there may be a need for a more personalized approach and fine tuning, in accordance with the patients' needs. This study aims to evaluate the individual experience of levodopa/carbidopa 5/1.25 mg microtablets (LC-5) in clinical practice with respect to efficacy, tolerability, and usability. The method used was as follows: patients answered a questionnaire concerning the effect and usability of LC-5, and their medical records were reviewed. Regarding results, thirty-five survey responses were obtained, and 29 patients' medical records were reviewed. The LC-5 dose dispenser usability was generally rated positively and facilitated medication adherence. The majority (85%) of patients reported symptom improvement while using LC-5, compared with previous standard treatments. These results suggest that LC-5 therapy is generally well-tolerated, with favorable patient-reported efficacy and user friendliness, as well as the possibility for an individualized, fine-tuned PD treatment. Further studies with a prospective design and larger study population are needed to confirm the results.
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| 46. |
- Grönlund, Eric, et al.
(author)
-
Dose painting of prostate cancer based on Gleason score correlations with apparent diffusion coefficients
- 2018
-
In: Acta Oncologica. - : Taylor & Francis. - 0284-186X .- 1651-226X. ; 57:5, s. 574-581
-
Journal article (peer-reviewed)abstract
- Background: Gleason scores for prostate cancer correlates with an increased recurrence risk after radiotherapy (RT). Furthermore, higher Gleason scores correlates with decreasing apparent diffusion coefficient (ADC) data from diffusion weighted MRI (DWI-MRI). Based on these observations, we present a formalism for dose painting prescriptions of prostate volumes based on ADC images mapped to Gleason score driven dose-responses.Methods: The Gleason score driven dose-responses were derived from a learning data set consisting of pre-RT biopsy data and post-RT outcomes for 122 patients treated with a homogeneous dose to the prostate. For a test data set of 18 prostate cancer patients with pre-RT ADC images, we mapped the ADC data to the Gleason driven dose-responses by using probability distributions constructed from published Gleason score correlations with ADC data. We used the Gleason driven dose-responses to optimize dose painting prescriptions that maximize the tumor control probability (TCP) with equal average dose as for the learning sets homogeneous treatment dose.Results: The dose painting prescriptions increased the estimated TCP compared to the homogeneous dose by 0–51% for the learning set and by 4–30% for the test set. The potential for individual TCP gains with dose painting correlated with increasing Gleason score spread and larger prostate volumes. The TCP gains were also found to be larger for patients with a low expected TCP for the homogeneous dose prescription.Conclusions: We have from retrospective treatment data demonstrated a formalism that yield ADC driven dose painting prescriptions for prostate volumes that potentially can yield significant TCP increases without increasing dose burdens as compared to a homogeneous treatment dose. This motivates further development of the approach to consider more accurate ADC to Gleason mappings, issues with delivery robustness of heterogeneous dose distributions, and patient selection criteria for design of clinical trials.
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| 47. |
- Grönlund, Eric, 1987-, et al.
(author)
-
Robust treatment planning of dose painting for prostate cancer based on ADC-to-Gleason score mappings : what is the potential to increase the tumor control probability?
- 2021
-
In: Acta Oncologica. - : Taylor & Francis. - 0284-186X .- 1651-226X. ; 60:2, s. 199-206
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Journal article (peer-reviewed)abstract
- Background and Purpose The aim of this study was to evaluate the potential to increase the tumor control probability (TCP) with ‘dose painting by numbers’ (DPBN) plans optimized in a treatment planning system (TPS) compared to uniform dose plans. The DPBN optimization was based on our earlier published formalism for prostate cancer that is driven by dose-responses of Gleason scores mapped from apparent diffusion coefficients (ADC).Material and MethodsFor 17 included patients, a set of DPBN plans were optimized in a TPS by maximizing the TCP for an equal average dose to the prostate volume (CTVT) as for a conventional uniform dose treatment. For the plan optimizations we applied different photon energies, different precisions for the ADC-to-Gleason mappings, and different CTVT positioning uncertainties. The TCP increasing potential was evaluated by the DPBN efficiency, defined as the ratio of TCP increases for DPBN plans by TCP increases for ideal DPBN prescriptions (optimized without considering radiation transport phenomena, uncertainties of the CTVT positioning, and uncertainties of the ADC-to-Gleason mapping).ResultsThe median DPBN efficiency for the most conservative planning scenario optimized with a low precision ADC-to-Gleason mapping, and a positioning uncertainty of 0.6 cm was 10%, meaning that more than half of the patients had a TCP gain of at least 10% of the TCP for an ideal DPBN prescription. By increasing the precision of the ADC-to-Gleason mapping, and decreasing the positioning uncertainty the median DPBN efficiency increased by up to 40%.ConclusionsTCP increases with DPBN plans optimized in a TPS were found more likely with a high precision mapping of image data into dose-responses and a high certainty of the tumor positioning. These findings motivate further development to ensure precise mappings of image data into dose-responses and to ensure a high spatial certainty of the tumor positioning when implementing DPBN clinically.
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| 48. |
- Hildeman, Anders, et al.
(author)
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Hildeman, A., Bolin, D., Wallin, J., Johansson, A., Nyholm, T., Asklund, T., and Yu, J. Whole-brain substitute CT generation using Markov random field mixture models.
- 2016
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Other publication (other academic/artistic)abstract
- Computed tomography (CT) equivalent information is needed for attenuation correction in PET imaging and for dose planning in radiotherapy. Prior work has shown that Gaussian mixture models can be used to generate a substitute CT (s-CT) image from a specific set of MRI modalities. This work introduces a more flexible class of mixture models for s-CT generation, that incorporates spatial dependency in the data through a Markov random field prior on the latent field of class memberships associated with a mixture model. Furthermore, the mixture distributions are extended from Gaussian to normal inverse Gaussian (NIG), allowing heavier tails and skewness. The amount of data needed to train a model for s-CT generation is of the order of 10^8 voxels. The computational efficiency of the parameter estimationand prediction methods are hence paramount, especially when spatial dependency is included in the models. A stochastic Expectation Maximization (EM) gradient algorithm is proposed in order to tackle this challenge. The advantages of the spatial model and NIG distributions are evaluated with a cross-validation study based ondata from 14 patients. The study show that the proposed model enhances the predictive quality of the s-CT images by reducing the mean absolute error with 17.9%. Also, the distribution of CT values conditioned on the MR images are better explainedby the proposed model as evaluated using continuous ranked probability scores.
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| 49. |
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| 50. |
- Hult, Ludvig, et al.
(author)
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Challenges in CATE estimation for NCCU data
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Other publication (other academic/artistic)abstract
- Sudden increase in intercranial pressure is a severe complication for patients in neuro-critical care. Machine learning models have been developed to predict such events, but they may suffer from confounding, not accounting for the impact of treatment decisions. Causal inference may be employed to estimate the impact of treatment, helping medical staff attend to those patients where treatment are effective. This work investigates the feasibility of conditional average treatment effect estimation on observational data from the neurocriticalcare unit at Uppsala Akademiska Hospital. We find that the selected CATE estimators have difficulties in estimating the treatment effect on a semisynthetic dataset. When used on the real dataset, the CATE estimators show poor agreement. We discuss the challenges and suggest future work to address them.
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