| 1. |
- Ljungberg, Michael, et al.
(författare)
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Introduction to the Monte Carlo Method
- 2012
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Ingår i: Monte Carlo Calculation in Nuclear Medicine: Applications in Diagnostic Imaging - second edition. ; , s. 1-16
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Bokkapitel (refereegranskat)
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| 2. |
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| 3. |
- Ljungberg, Michael, et al.
(författare)
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The SIMIND Monte Carlo program
- 2012
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Ingår i: Monte Carlo Calculation in Nuclear Medicine: Applications in Diagnostic Imaging - second edition. ; , s. 111-128
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Bokkapitel (refereegranskat)
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| 4. |
- Carlsson, Gudrun Alm, et al.
(författare)
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Basic Atomic and Nuclear Physics
- 2022. - 1
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Ingår i: Handbook of Nuclear Medicine and Molecular Imaging for Physicists : Instrumentation and Imaging Procedures, Volume I - Instrumentation and Imaging Procedures, Volume I. - 9781138593268 - 9780429489556 ; 1, s. 15-37
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Bokkapitel (refereegranskat)abstract
- Nuclear medicine and molecular imaging are mostly based on radioactive elements that, when decaying due to an excess of energy, emit radiation in the form of electromagnetic radiation (photons), or by charge-particles (electron, positrons, or alpha particles). The first part of this chapter describes in general the atom and its components and states some definitions important for further reading. There are several ways that a nucleus can decay (by alpha, beta+, and beta decay, electron capture and internal conversion). Each of these processes together with the conditions required for such a decay, are discussed in the chapter. In several of these decays there are also secondary emissions, such as characteristic x-rays and Auger electrons, and these are described together with which conditions they become important. Decay processes are generally described in the literature by decay schemes, and the chapter therefore includes a section on how these schemes are constructed and how to read them. The nature of the decay rate (the activity) is described since this is a fundamental quantity in the nuclear medicine field together with some examples of more complex decays.
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| 5. |
- Ljungberg, Michael, et al.
(författare)
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Basics of Radiation Interactions in Matter
- 2022. - 1
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Ingår i: Handbook of Nuclear Medicine and Molecular Imaging for Physicists : Instrumentation and Imaging Procedures - Instrumentation and Imaging Procedures. - 9781138593268 - 9780429489556 ; 1
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Bokkapitel (refereegranskat)abstract
- Both electromagnetic radiation (photons) and charged particles interact with matter and by different interaction processes result in energy deposition. This is the core of virtually all nuclear medicine applications because it is from the charged-particle interactions and related energy depositions that we can measure the scintillation light in SPECT and PET systems and from this create diagnostic images and perform radionuclide therapy for treatment of cancer and other diseases. This chapter provides the basic knowledge of radiation transport and how the particles are affected by the composition of the material in which they travel (e.g., tissue composition in a patient or a detector material). The most important interaction processes for photons and charged particles are described in detail for energies, relevant for nuclear medicine applications, together with their related cross sections (probability for interactions) and energy, angular, and material dependence. Although they are not frequently used in nuclear-medicine applications, the chapter describes the neutron and its type of interactions. The ranges of the path length of charged particles and how this depends on type of particle and kinetic energy are important factors to consider for dosimetry calculations and for radiation protection. The chapter describes the relations between particle range and the deposition of energy per unit length for different types of particles.
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| 6. |
- Ljungberg, Michael, et al.
(författare)
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Introduction to the Monte Carlo Method
- 1998
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Ingår i: Monte Carlo Calculations in Nuclear Medicine: Applications in Diagnostic Imaging. - 750304790 ; , s. 37-37
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 7. |
- Ljungberg, Michael, et al.
(författare)
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Single Photon Emission Computed Tomography (SPECT) and SPECT/CT Hybrid Imaging
- 2022. - 1
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Ingår i: Handbook of Nuclear Medicine and Molecular Imaging for Physicists : Instrumentation and Imaging Procedures - Instrumentation and Imaging Procedures. - 9781138593268 - 9780429489556 ; 1
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Bokkapitel (refereegranskat)abstract
- Images created using a standard collimator-based scintillation camera are essentially 2D images, lacking information regarding the source depth, since the value in a particular pixel in the image represents detection of photons along a line determined by the collimator. However, it is possible to reconstruct a set of 2D images that together form a 3D image of the underlying activity distribution from data acquired of the same source distribution at different projection angles around the object. This chapter will describe the way in which these data can be used to reconstruct transversal images by the filtered back-projection (FBP) method as well as by iterative algorithms, and also how noise regularization can be implemented. Various physical factors that affect the reconstructed images will also be discussed. If we combine a SPECT system with a CT system and display the images from both as a single hybrid image, additional useful information can be obtained. The CT information can also be used to correct for non-homogeneous attenuation, scatter, and partial-volume effects. Finally, the chapter will discuss how the combination of quantitative SPECT images registered to CT images can be used for dosimetry calculations.
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| 8. |
- Sarrut, David, et al.
(författare)
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Monte Carlo Simulation of Nuclear Medicine Imaging Systems
- 2022. - 1
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Ingår i: Handbook of Nuclear Medicine and Molecular Imaging for Physicists : Instrumentation and Imaging Procedures - Instrumentation and Imaging Procedures. - 9781138593268 - 9780429489556 ; 1
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Bokkapitel (refereegranskat)abstract
- This chapter describes the use of the Monte Carlo method to simulate nuclear medicine imaging systems, mainly the scintillation camera – SPECT (Single-Photon Emission Computed Tomography) and PET (Positron Emission Tomography) – systems that are major tools in nuclear medicine to produce images of activity distributions. The first part describes the principles behind the Monte Carlo method, in particular, how to select a stochastic variable from known probability distribution functions using uniform random numbers and, in more detail, how to sample photon interaction processes such as sampling photon path-length, photon interactions and scattering resulting in change in energy and direction. The improvement in calculation efficiency by implementation of various variance-reduction methods is also described. The second part describes in more detail two Monte Carlo codes, SIMIND and GATE, that for many years have been widely used for simulation of medical imaging. The potentials of these programs and how a user runs these programs are described by several explicit examples. Also described are applications where these codes have been useful, such as in image reconstruction, modelling of scatter and collimator septum penetration effects, and evaluation of pre-clinical imaging systems. Some perspectives, such as artificial intelligence approaches, SiPM-based SPECT/PET systems, or the electronically collimated Compton camera are also discussed.
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| 9. |
- Sera, Terez, et al.
(författare)
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Multicentre Studies
- 2022. - 1
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Ingår i: Handbook of Nuclear Medicine and Molecular Imaging for Physicists : Instrumentation and Imaging Procedures - Instrumentation and Imaging Procedures. - 9781138593268 - 9780429489556 ; 1
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Bokkapitel (refereegranskat)abstract
- The first part of the chapter provides an introduction on the implementation of quality-assurance programmes in nuclear medicine (NM) services. It is argued that participation in interlaboratory comparisons has two main benefits. First, on top of existing local quality-assurance programmes, participation can add a level of reassurance on quality. Second, interlaboratory comparisons are prerequisite for clinical multicentre trials. The success of an interlaboratory comparison depends on many parameters, this chapter will discuss financing, selection, and procurement of the quality-control devices and selection of participants. The discussion on the execution and evaluation of a multicentre study is followed by the presentation of potential problems and recommendations on how to avoid them. The chapter discusses the most widely known interlaboratory quality-assurance programmes, including the EANM/EARL 18-F FDG PET/CT accreditation programme and the DAT-Scan SPECT standardization programme. In the second part, examples of multicentre studies, based on Monte-Carlo simulated scintillation camera imaging and a computer phantom, with the aims of investigating how different clinical sites perform evaluation using the routine. These studies started in Sweden 2012 and have included renography, bone scintigraphy, lung scintigraphy, and myocardial studies. The camera- and acquisition parameters for each site were considered, and images were distributed by Dicom files to be read in and processed as they were coming from the site’s own camera. The outcome from the evaluation was then compared to the truth (i.e., the known disease, abnormality, change in function) as defined by the activity distribution in the computer phantom.
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| 10. |
- Wang, Zhaoming, et al.
(författare)
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Imputation and subset-based association analysis across different cancer types identifies multiple independent risk loci in the TERT-CLPTM1L region on chromosome 5p15.33
- 2014
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Ingår i: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 23:24, s. 6616-6633
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Tidskriftsartikel (refereegranskat)abstract
- Genome-wide association studies (GWAS) have mapped risk alleles for at least 10 distinct cancers to a small region of 63 000 bp on chromosome 5p15.33. This region harbors the TERT and CLPTM1L genes; the former encodes the catalytic subunit of telomerase reverse transcriptase and the latter may play a role in apoptosis. To investigate further the genetic architecture of common susceptibility alleles in this region, we conducted an agnostic subset-based meta-analysis (association analysis based on subsets) across six distinct cancers in 34 248 cases and 45 036 controls. Based on sequential conditional analysis, we identified as many as six independent risk loci marked by common single-nucleotide polymorphisms: five in the TERT gene (Region 1: rs7726159, P = 2.10 × 10(-39); Region 3: rs2853677, P = 3.30 × 10(-36) and PConditional = 2.36 × 10(-8); Region 4: rs2736098, P = 3.87 × 10(-12) and PConditional = 5.19 × 10(-6), Region 5: rs13172201, P = 0.041 and PConditional = 2.04 × 10(-6); and Region 6: rs10069690, P = 7.49 × 10(-15) and PConditional = 5.35 × 10(-7)) and one in the neighboring CLPTM1L gene (Region 2: rs451360; P = 1.90 × 10(-18) and PConditional = 7.06 × 10(-16)). Between three and five cancers mapped to each independent locus with both risk-enhancing and protective effects. Allele-specific effects on DNA methylation were seen for a subset of risk loci, indicating that methylation and subsequent effects on gene expression may contribute to the biology of risk variants on 5p15.33. Our results provide strong support for extensive pleiotropy across this region of 5p15.33, to an extent not previously observed in other cancer susceptibility loci.
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| 11. |
- af Rosenschöld, Per Munck, et al.
(författare)
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The MCNP Monte Carlo Program
- 2012. - 2nd
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Ingår i: Monte Carlo Calculations in Nuclear Medicine : Applications in Diagnostic Imaging - Applications in Diagnostic Imaging. - : Taylor & Francis. - 9781439841099 - 9781439841105 ; , s. 153-172
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Bokkapitel (refereegranskat)abstract
- Monte Carlo N-Particle (MCNP) is a Monte Carlo code package allowing coupled neutron, photon, and electron transport calculations. Also, the possibility of performing heavy charged particle transport calculations was recently introduced with the twin MCNPX code package. An arbitrary three-dimensional problem can be formulated through the use of surfaces defining building blocks (“cells” that are assigned density, material, and relevant cross-section tables. The source can be specified as point, surface, or volumes using generic or as a phase/space file.
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| 12. |
- Bousquet, Jean, et al.
(författare)
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ARIA digital anamorphosis : Digital transformation of health and care in airway diseases from research to practice
- 2021
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Ingår i: Allergy. European Journal of Allergy and Clinical Immunology. - : John Wiley & Sons. - 0105-4538 .- 1398-9995. ; 76:1, s. 168-190
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Forskningsöversikt (refereegranskat)abstract
- Digital anamorphosis is used to define a distorted image of health and care that may be viewed correctly using digital tools and strategies. MASK digital anamorphosis represents the process used by MASK to develop the digital transformation of health and care in rhinitis. It strengthens the ARIA change management strategy in the prevention and management of airway disease. The MASK strategy is based on validated digital tools. Using the MASK digital tool and the CARAT online enhanced clinical framework, solutions for practical steps of digital enhancement of care are proposed.
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| 13. |
- Dabestani, Saeed, et al.
(författare)
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Local treatments for metastases of renal cell carcinoma: a systematic review
- 2014
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Ingår i: The Lancet Oncology. - : Elsevier. - 1474-5488 .- 1470-2045. ; 15:12, s. 549-561
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Forskningsöversikt (refereegranskat)abstract
- Local treatment of metastases such as metastasectomy or radiotherapy remains controversial in the treatment of metastatic renal cell carcinoma. To investigate the benefits and harms of various local treatments, we did a systematic review of all types of comparative studies on local treatment of metastases from renal cell carcinoma in any organ. Interventions included metastasectomy, radiotherapy modalities, and no local treatment. The results suggest that patients treated with complete metastasectomy have better survival and symptom control (including pain relief in bone metastases) than those treated with either incomplete or no metastasectomy. Nevertheless, the available evidence was marred by high risks of bias and confounding across all studies. Although the findings presented here should be interpreted with caution, they and the identified gaps in knowledge should provide guidance for clinicians and researchers, and directions for further research.
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| 14. |
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| 15. |
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| 16. |
- Garkavij, Michael, et al.
(författare)
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Lu-177-[DOTA0,Tyr3] Octreotate Therapy in Patients With Disseminated Neuroendocrine Tumors: Analysis of Dosimetry With Impact on Future Therapeutic Strategy
- 2010
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Ingår i: Cancer. - : Wiley. - 1097-0142 .- 0008-543X. ; 116:4, s. 1084-1092
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Lu-177-(DOTAO,Tyr3) octreotate is a new treatment modality for disseminated neuroendocrine tumors. According to a consensus protocol, the calculated maximally tolerated absorbed dose to the kidney should not exceed 27 Gy. In commonly used dosimetry methods, planar imaging is used for determination of the residence time, whereas the kidney mass is determined from a computed tomography (CT) scan. METHODS: Three different quantification methods were used to evaluate the absorbed dose to the kidneys. The first method involved common planar activity imaging, and the absorbed dose was calculated using the medical internal radiation dose (MIRD) formalism, using CT scan-based kidney masses. For this method, 2 region of interest locations for the background correction were investigated. The second method also included single-photon emission computed tomography (SPECT) data, which were used to scale the amplitude of the time-activity curve obtained from planar images. The absorbed dose was calculated as in the planar method. The third method used quantitative SPECT images converted to absorbed dose rate images, where the median absorbed dose rate in the kidneys was calculated in a volume of interest defined over the renal cortex. RESULTS: For some patients, the results showed a large difference in calculated kidney-absorbed doses, depending on the dosimetry method. The 2 SPECT-based methods generally gave consistent values, although the calculations were based on different assumptions. Dosimetry using the baseline planar method gave higher absorbed doses in all patients. The values obtained from planar imaging with a background region of interest placed adjacent to the kidneys were more consistent with dosimetry also including SPECT. For the accumulated tumor absorbed dose, the first 2 of the 4 planned therapy cycles made the major contribution. CONCLUSIONS: The results suggested that patients evaluated according to the conventional planar-based dosimetry method may have been undertreated compared with the other methods. Hematology and creatinine did not indicate any restriction for a more aggressive approach, which would be especially useful in patients with more aggressive tumors where there is not time for more protracted therapy. Cancer 2010;116(4 suppl):1084-92. (C) 2010 American Cancer Society.
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| 17. |
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| 18. |
- Gaziano, Liam, et al.
(författare)
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Mild-to-moderate kidney dysfunction and cardiovascular disease : Observational and mendelian randomization analyses
- 2022
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Ingår i: Circulation. - : Wolters Kluwer. - 0009-7322 .- 1524-4539. ; 146:20, s. 1507-1517
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: End-stage renal disease is associated with a high risk of cardiovascular events. It is unknown, however, whether mild-to-moderate kidney dysfunction is causally related to coronary heart disease (CHD) and stroke.METHODS: Observational analyses were conducted using individual-level data from 4 population data sources (Emerging Risk Factors Collaboration, EPIC-CVD [European Prospective Investigation into Cancer and Nutrition-Cardiovascular Disease Study], Million Veteran Program, and UK Biobank), comprising 648 135 participants with no history of cardiovascular disease or diabetes at baseline, yielding 42 858 and 15 693 incident CHD and stroke events, respectively, during 6.8 million person-years of follow-up. Using a genetic risk score of 218 variants for estimated glomerular filtration rate (eGFR), we conducted Mendelian randomization analyses involving 413 718 participants (25 917 CHD and 8622 strokes) in EPIC-CVD, Million Veteran Program, and UK Biobank.RESULTS: There were U-shaped observational associations of creatinine-based eGFR with CHD and stroke, with higher risk in participants with eGFR values <60 or >105 mL·min-1·1.73 m-2, compared with those with eGFR between 60 and 105 mL·min-1·1.73 m-2. Mendelian randomization analyses for CHD showed an association among participants with eGFR <60 mL·min-1·1.73 m-2, with a 14% (95% CI, 3%-27%) higher CHD risk per 5 mL·min-1·1.73 m-2 lower genetically predicted eGFR, but not for those with eGFR >105 mL·min-1·1.73 m-2. Results were not materially different after adjustment for factors associated with the eGFR genetic risk score, such as lipoprotein(a), triglycerides, hemoglobin A1c, and blood pressure. Mendelian randomization results for stroke were nonsignificant but broadly similar to those for CHD.CONCLUSIONS: In people without manifest cardiovascular disease or diabetes, mild-to-moderate kidney dysfunction is causally related to risk of CHD, highlighting the potential value of preventive approaches that preserve and modulate kidney function.
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| 19. |
- Hademenos, George J, et al.
(författare)
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A Monte Carlo Investigation of the Dual Photopeak Window Scatter Correction Method
- 1993
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Ingår i: IEEE Transactions on Nuclear Science. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9499 .- 1558-1578. ; 40:2, s. 179-185
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Tidskriftsartikel (refereegranskat)abstract
- Results from a Monte Carlo investigation of the dual photopeak window (DPW) scatter correction method are presented for point and extended sources of Tc-99m in both homogeneous and nonhomogeneous attenuating media. The DPW method uses the ratio of counts in two nonoverlapping energy windows within the photopeak region as input to a regression relation. A pixel-by-pixel estimate of the scatter in the summed windows is obtained and subtracted to yield an estimate of the primary. An approximate tenfold decrease in the scatter fraction and an excellent agreement with the shape of the true scatter distribution were observed.
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| 20. |
- Hademenos, George J, et al.
(författare)
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A Scatter Correction Method for 201-Tl images: A Monte Carlo Investigation
- 1993
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Ingår i: IEEE Transactions on Nuclear Science. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9499 .- 1558-1578. ; 40:4, s. 1179-1186
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Tidskriftsartikel (refereegranskat)abstract
- Results from the application of a modified dual photopeak window scatter correction method to Monte Carlo simulated Tl-201 emission images are presented. In the Monte Carlo investigation, individual simulations are performed for six radiation emissions of Tl-201. For each emission, point sources of Tl-201 are imaged at various locations in a water-filled elliptical tub phantom using three energy windows. The DPW method is applied to each point source image to estimate the scatter distribution. For point source images in both homogeneous and nonhomogeneous attenuating media, the application of this modified version of DPW results in an approximately sixfold reduction in the scatter fraction and an excellent agreement of the shape of the tails between the estimated scatter distribution and the Monte Carlo-simulated truth. This method is also applied to two views of an extended cardiac distribution within an anthropomorphic phantom, again resulting in at least a sixfold improvement between the scatter estimate and the Monte Carlo-simulated true scatter.
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| 21. |
- Hademenos, George J, et al.
(författare)
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The Influence of Phantom Size, Shape, and Density, and Collimator Selection on the Dual Photopeak Scatter Correction Method
- 1994
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Ingår i: IEEE Transactions on Nuclear Science. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9499 .- 1558-1578. ; 41:1-2, s. 364-368
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Tidskriftsartikel (refereegranskat)abstract
- Results from a Monte Carlo investigation are presented for the application of the dual photopeak window (DPW) scatter correction method to phantom geometries of varying shapes, sizes, and densities as well as to several collimators. A Monte Carlo program was used to simulate a Tc-99m point source at locations of 0.5 cm from the phantom surface, at the center, 0.5 cm from the bottom, and 4/5 the distance lateral from the center for each case of variation. DPW was then used to correct for scatter using a regression relation determined for a 30.5 cm×23.0 cm water-filled elliptical tub phantom using an ultrahigh resolution collimator. The application of DPW in all cases accounted for an approximate twelve-fold reduction in scatter fraction with an excellent agreement between the true scatter and scatter estimate distributions both at the tails and under the peak of the point spread functions.
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| 22. |
- King, Michael A., et al.
(författare)
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A Monte Carlo investigation of artifacts caused by liver uptake in single-photon emission computed tomography perfusion imaging with technetium 99m-labeled agents
- 1996
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Ingår i: Journal of Nuclear Cardiology. - 1532-6551. ; 3:1, s. 18-29
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Significant hepatobiliary accumulation of technetium 99m-labeled cardiac perfusion agents has been shown to cause alterations in the apparent localization of the agents in the cardiac walls. A Monte Carlo study was conducted to investigate the hypothesis that the cardiac count changes are due to the inconsistencies in the projection data input to reconstruction, and that correction of the causes of these inconsistencies before reconstruction, or including knowledge of the physics underlying them in the reconstruction algorithm, would virtually eliminate these artifacts. METHODS AND RESULTS: The SIMIND Monte Carlo package was used to simulate 64 x 64 pixel projection images at 128 angles of the three-dimensional mathematical cardiac-torso (MCAT) phantom. Simulations were made of (1) a point source in the liver, (2) cardiac activity only, and (3) hepatic activity only. The planar projections and reconstructed point spread functions (PSFs) of the point source in the liver were investigated to study the nature of the inconsistencies introduced into the projections by imaging, and how these affect the distribution of counts in the reconstructed slices. Bull's eye polar maps of the counts at the center of the left ventricular wall of filtered back-projection (FBP) and maximum-likelihood expectation-maximization (MLEM) reconstructions of projections with solely cardiac activity, and with cardiac activity plus hepatic activity scaled to have twice the cardiac concentration, were compared to determine the magnitude and location of apparent changes in cardiac activity when hepatic activity is present. Separate simulations were made to allow the investigation of stationary spatial resolution, distance-dependent spatial resolution, attenuation, and scatter. The point source projections showed significant inconsistencies as a function of projection angle with the largest effect being caused by attenuation. When consistent projections were simulated, no significant impact of hepatic activity on cardiac counts was noted with FBP, or 100 iterations of MLEM. With inconsistent projections, reconstruction of 180 degrees resulted in greater apparent cardiac count losses than did 360 degrees reconstruction for both FBP and MLEM. The incorporation of attenuation correction in MLEM reconstruction reduced the changes in cardiac counts to that seen in simulations in which attenuation was not included, but resulted in increased apparent localization of activity in the posterior wall of the left ventricle when scatter was present in the simulated images. CONCLUSIONS: The apparent alterations in cardiac counts when significant hepatic localization is present is due to the inconsistency of the projections inherent in imaging. Prior correction of these, or accounting for them in the reconstruction algorithm, will virtually eliminate them as causes of artifactual changes in localization. Attenuation correction and scatter correction are both required to overcome the major sources of apparent count changes in the heart associated with hepatic uptake.
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| 23. |
- Lardas, Michael, et al.
(författare)
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Systematic Review of Surgical Management of Nonmetastatic Renal Cell Carcinoma with Vena Caval Thrombus
- 2016
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Ingår i: European Urology. - : Elsevier BV. - 0302-2838 .- 1873-7560. ; 70:2, s. 265-280
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Forskningsöversikt (refereegranskat)abstract
- CONTEXT: Overall, 4-10% of patients with renal cell carcinoma (RCC) present with venous tumour thrombus. It is uncertain which surgical technique is best for these patients. Appraisal of outcomes with differing techniques would guide practice.OBJECTIVE: To systematically review relevant literature comparing the outcomes of different surgical therapies and approaches in treating vena caval thrombus (VCT) from nonmetastatic RCC.EVIDENCE ACQUISITION: Relevant databases (Medline, Embase, and the Cochrane Library) were searched to identify relevant comparative studies. Risk of bias and confounding assessments were performed. A narrative synthesis of the evidence was presented.EVIDENCE SYNTHESIS: The literature search identified 824 articles. Fourteen studies reporting on 2262 patients were included. No distinct surgical method was superior for the excision of VCT, although the method appeared to be dependent on tumour thrombus level. Minimal access techniques appeared to have better perioperative and recovery outcomes than traditional median sternotomy, but the impact on oncologic outcomes is unknown. Preoperative renal artery embolisation did not offer any oncologic benefits and instead resulted in significantly worse perioperative and recovery outcomes, including possibly higher perioperative mortality. The comparison of cardiopulmonary bypass versus no cardiopulmonary bypass showed no differences in oncologic outcomes. Overall, there were high risks of bias and confounding.CONCLUSIONS: The evidence base, although derived from retrospective case series and complemented by expert opinion, suggests that patients with nonmetastatic RCC and VCT and acceptable performance status should be considered for surgical intervention. Despite a robust review, the findings were associated with uncertainty due to the poor quality of primary studies available. The most efficacious surgical technique remains unclear.PATIENT SUMMARY: We examined the literature on the benefits of surgery to remove kidney cancers that have spread to neighbouring veins. The results suggest such surgery, although challenging and associated with high risk of complications, appears to be feasible and effective and should be contemplated for suitable patients if possible; however, many uncertainties remain due to the poor quality of the data.
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| 24. |
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| 25. |
- Lindén, Ola, et al.
(författare)
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Radioimmunotherapy using 131I-labeled anti-CD22 monoclonal antibody (LL2) in patients with previously treated B-cell lymphomas
- 1999
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Ingår i: Clinical Cancer Research. - 1078-0432. ; 5:10 Suppl, s. 3287-3291
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Tidskriftsartikel (refereegranskat)abstract
- Experience in using rapidly internalizing antibodies, such as the anti-CD22 antibody, for radioimmunotherapy of B-cell lymphomas is still limited. The present study was conducted to assess the efficacy and toxicity of a 131I-labeled anti-CD22 monoclonal antibody (mAb), LL2, in patients with B-cell lymphomas failing first- or second-line chemotherapy. Eligible patients were required to have measurable disease, less than 25% B cells in unseparated bone marrow, and an uptake of 99mTc-labeled LL2Fab' in at least one lymphoma lesion on immunoscintigram. Eight of nine patients examined with immunoscintigraphy were unequivocally found to have an uptake, and therapy with 131I-labeled anti-CD22 [1330 MBq/m2 (36 mCi/m2)] preceded by 20 mg of naked anti-CD22 mAb was administered. Three patients achieved partial remission (duration, 12, 3, and 2 months), and one patient with progressive lymphoma showed stable disease for 17 months. Four patients exhibited progressive disease. The toxicity was hematological. Patients with subnormal counts of neutrophils or platelets before therapy seemed to be more at risk for hematological side effects. Radioimmunotherapy in patients with B-cell lymphomas using 131I-labeled mouse anti-CD22 can induce objective remission in patients with aggressive as well as indolent lymphomas who have failed prior chemotherapy.
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| 26. |
- Ljungberg, Michael, et al.
(författare)
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Comparison of four scatter correction methods using Monte Carlo simulated source distributions
- 1994
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Ingår i: Journal of Nuclear Medicine. - 0161-5505. ; 35:1, s. 143-151
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Tidskriftsartikel (refereegranskat)abstract
- Scatter correction in SPECT is important for improving image quality, boundary detection and the quantification of activity in different regions. This paper presents a comparison of four scatter correction methods, three using more than one energy window and one convolution-subtraction correction method using spatial variant scatter line-spread functions. METHODS: The comparison is based on Monte Carlo simulated data for point sources on- and off-axis, hot and cold spheres of different diameters, and a clinically realistic source distribution simulating brain imaging. All studies were made for a uniform cylindrical water phantom. Since the nature of the detected photon is known with Monte Carlo simulation, separate images of primary and scattered photons can be recorded. These can then be compared with estimated scatter and primary images obtained from the different scatter correction methods. The criteria for comparison were the normalized mean square error, scatter fraction, % recovery and image contrast. RESULTS: All correction methods significantly improved image quality and quantification compared to those obtained with no correction. Quantitatively, no single method was observed to be the best by all criteria for all the source distributions. Three of the methods were observed to perform the best by at least one of the criteria for one of the source distributions. For brain imaging, the differences between all the methods were much less than the difference between them and no correction at all. CONCLUSION: It is concluded that performing scatter correction is essential for accurate quantification, and that all four methods yield a good, but not perfect, scatter correction. Since it is hard to distinguish the methods consistently in terms of their performance, it may be that the choice should be made on the basis of ease of implementation.
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| 27. |
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| 28. |
- Ljungberg, Michael, et al.
(författare)
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Monte Carlo Simulation of Transmission Studies using a Planar Sources with a Parallel Collimator and a Line Source with a Fan-Beam Collimators
- 1994
-
Ingår i: IEEE Transactions on Nuclear Science. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9499 .- 1558-1578. ; 41:4, s. 1577-1584
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Tidskriftsartikel (refereegranskat)abstract
- A knowledge of the distribution of the attenuation coefficient is generally required for a successful correction of attenuation in nonhomogeneous regions. This can be accomplished by performing transmission measurement with either parallel or fan-bean collimation. The Monte Carlo method makes it possible to fully evaluate the results of such a correction. This study shows results from such simulations for both parallel and fan-beam transmission imaging. Also, examples of the effect of down-scatter from an emission 99mTc radionuclide into the energy window for a transmission 153Gd radionuclide are shown.
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| 29. |
- Ljungberg, Michael, et al.
(författare)
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Quantitative single photon emission tomography: verification for sources in an elliptical water phantom
- 1992
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Ingår i: European Journal Of Nuclear Medicine. - 1432-105X. ; 19:10, s. 838-844
-
Tidskriftsartikel (refereegranskat)abstract
- Accurate absorbed dose calculations are important for a proper dose planning in internal radionuclide therapy. The activity distribution must be measured and the target volume defined. This can be done with single photon emission tomography (SPET) if proper attenuation and scatter correction are employed. This study investigated the calculation of the activity and the volume of different spherical sources. These two parameters are essential for a proper dose calculation. The scatter and attenuation correction method is based on spatially variant scatter functions and density maps. The volume calculation method is based on obtaining a threshold from a grey-level histogram. Both point sources and spheres of different diameters containing technetium-99m were placed in different locations in an elliptical water phantom and imaged by SPET. The activity and the volume of the spheres were calculated from the SPET images and compared with known activities. Results show a quantification of activity within 10% for most of the sources. Important influences on the quantification are (a) the presence of artefacts due to improper reconstruction and (b) the finite spatial resolution which affects the total number of counts within the determined volume.
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| 30. |
- Malusek, Alexandr, 1968-
(författare)
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Calculation of scatter in cone beam CT : Steps towards a virtual tomograph
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Scattered photons—shortly scatter—are generated by interaction processes when photon beams interact with matter. In diagnostic radiology, they deteriorate image quality since they add an undesirable signal that lowers the contrast in projection radiography and causes cupping and streak artefacts in computed tomography (CT). Scatter is one of the most detrimental factors in cone beam CT owing to irradiation geometries using wide beams. It cannot be fully eliminated, nevertheless its amount can be lowered via scatter reduction techniques (air gaps, antiscatter grids, collimators) and its effect on medical images can be suppressed via scatter correction algorithms.Aim: Develop a tool—a virtual tomograph—that simulates projections and performs image reconstructions similarly to a real CT scanner. Use this tool to evaluate the effect of scatter on projections and reconstructed images in cone beam CT. Propose improvements in CT scanner design and image reconstruction algorithms.Methods: A software toolkit (CTmod) based on the application development framework ROOT was written to simulate primary and scatter projections using analytic and Monte Carlo methods, respectively. It was used to calculate the amount of scatter in cone beam CT for anthropomorphic voxel phantoms and water cylinders. Configurations with and without bowtie filters, antiscatter grids, and beam hardening corrections were investigated. Filtered back-projection was used to reconstruct images. Automatic threshold segmentation of volumetric CT data of anthropomorphic phantoms with known tissue compositions was tested to evaluate its usability in an iterative image reconstruction algorithm capable of performing scatter correction.Results: It was found that computer speed was the limiting factor for the deployment of this method in clinical CT scanners. It took several hours to calculate a single projection depending on the complexity of the geometry, number of simulated detector elements, and statistical precision. Data calculated using the CTmod code confirmed the already known facts that the amount of scatter is almost linearly proportional to the beam width, the scatter-to-primary ratio (SPR) can be larger than 1 for body-size objects, and bowtie filters can decrease the SPR in certain regions of projections. Ideal antiscatter grids significantly lowered the amount of scatter. The beneficial effect of classical antiscatter grids in cone beam CT with flat panel imagers was not confirmed by other researchers nevertheless new grid designs are still being tested. A simple formula estimating the effect of scatter on the quality of reconstructed images was suggested and tested.Conclusions: It was shown that computer simulations could calculate the amount of scatter in diagnostic radiology. The Monte Carlo method was too slow for a routine use in contemporary clinical practice nevertheless it could be used to optimize CT scanner design and, with some enhancements, it could become a part of an image reconstruction algorithm that performs scatter correction.
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| 31. |
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| 32. |
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| 33. |
- Pan, Tin-Su, et al.
(författare)
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Segmentation of the Body and Lungs from Compton Scatter and Photopeak Window Images in SPECT: A Monte Carlo Investigation
- 1996
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Ingår i: IEEE Transactions on Medical Imaging. - 1558-254X. ; 15:1, s. 13-24
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Tidskriftsartikel (refereegranskat)abstract
- In SPECT imaging of the chest, nonuniform attenuation correction requires use of a patient specific attenuation (p)map. Such a map can be obtained by estimating the regions of 1)the lungs and 2) the soft tissues and bones, and then assigning an appropriate value of attenuation coefficient (p) to each region. We proposed a method to segment such regions from the Compton scatter and photopeak window SPECT slices of Tc-99m Sestamibi studies. The Compton scatter slices are used to segment the body outline and to estimate the regions of the lungs. Locations of the back bone and sternum are estimated from the photopeak window slices to assist in the segmentation. To investigate the accuracy of using Compton scatter slices in estimating the regions of the body and the lungs, a Monte-Carlo SPECT simulation of an anthropomorphic phantom with an activity distribution and noise characteristics similar to patient data was conducted. Energy windows of various widths were simulated for use in locating a suitable Compton scatter window for imaging. The effects of attenuation correction using a p map based on segmentation were also studied. The results demonstrated for the activity and p maps studied herein that: 1) reasonable contrast could be obtained from Compton scatter data for the segmentation of the lung regions, 2) true positive rates of 99% and 89% for determining the body and lung regions, respectively, with total error rates of 4% and 29%, could be achieved, 3) usage of a p map based on segmentation for attenuation correction improved relative quantification over filtered backprojection, 4) variations in the assigned p value of 40% smaller or 40% larger in the lung regions had an insignificant impact on the results of relative quantification, 5) a wide energy window away from the photopeak window for recording scattered events could benefit both the segmentation of the lung regions and the attenuation correction of the activity in the myocardium region, and 6) usage of a smaller than true p value in the lung regions of an assigned p map might benefit attenuation correction for absolute quantification.
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| 34. |
- Sampson, Joshua N., et al.
(författare)
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Analysis of Heritability and Shared Heritability Based on Genome-Wide Association Studies for 13 Cancer Types
- 2015
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Ingår i: Journal of the National Cancer Institute. - : Oxford University Press (OUP). - 0027-8874 .- 1460-2105. ; 107:12
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Tidskriftsartikel (refereegranskat)abstract
- Background: Studies of related individuals have consistently demonstrated notable familial aggregation of cancer. We aim to estimate the heritability and genetic correlation attributable to the additive effects of common single-nucleotide polymorphisms (SNPs) for cancer at 13 anatomical sites. Methods: Between 2007 and 2014, the US National Cancer Institute has generated data from genome-wide association studies (GWAS) for 49 492 cancer case patients and 34 131 control patients. We apply novel mixed model methodology (GCTA) to this GWAS data to estimate the heritability of individual cancers, as well as the proportion of heritability attributable to cigarette smoking in smoking-related cancers, and the genetic correlation between pairs of cancers. Results: GWAS heritability was statistically significant at nearly all sites, with the estimates of array-based heritability, h(l)(2), on the liability threshold (LT) scale ranging from 0.05 to 0.38. Estimating the combined heritability of multiple smoking characteristics, we calculate that at least 24% (95% confidence interval [CI] = 14% to 37%) and 7% (95% CI = 4% to 11%) of the heritability for lung and bladder cancer, respectively, can be attributed to genetic determinants of smoking. Most pairs of cancers studied did not show evidence of strong genetic correlation. We found only four pairs of cancers with marginally statistically significant correlations, specifically kidney and testes (rho = 0.73, SE = 0.28), diffuse large B-cell lymphoma (DLBCL) and pediatric osteosarcoma (rho = 0.53, SE = 0.21), DLBCL and chronic lymphocytic leukemia (CLL) (rho = 0.51, SE = 0.18), and bladder and lung (rho = 0.35, SE = 0.14). Correlation analysis also indicates that the genetic architecture of lung cancer differs between a smoking population of European ancestry and a nonsmoking Asian population, allowing for the possibility that the genetic etiology for the same disease can vary by population and environmental exposures. Conclusion: Our results provide important insights into the genetic architecture of cancers and suggest new avenues for investigation.
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| 35. |
- Strand, Sven-Erik, et al.
(författare)
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Radio-immunotherapy dosimetry with special emphasis on SPECT quantification and extracorporeal immuno-adsorption
- 1994
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Ingår i: Medical & Biological Engineering & Computing. - 0140-0118. ; 32:5, s. 551-561
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Forskningsöversikt (refereegranskat)abstract
- Results from therapeutic trials with radiolabelled monoclonal antibodies are difficult to compare, because of lack of accurate macroscopic and microscopic dosimetry for both tumours and normal tissues. Requirements for such a dosimetry are covered in the paper. Accurate in vivo dosimetric measurement techniques for verification of calculated absorbed doses are also needed to verify treatment planning. In the review, important topics related to dosimetry in therapeutic trials in RIT are covered, such as, absorbed-dose calculations and activity-quantification techniques for planar imaging and SPECT. The latter is particularly discussed, including a summary of different correction techniques. Absorbed-dose calculations and treatment-planning techniques are also discussed. Possible ways of enhancing the therapeutic ratio are reviewed, especially the novel technique with extracorporeal immuno-adsorption. The review could form the basis of the development of future treatment-planning protocols and for dosimetry calculations in radio-immunotherapy, considering some of the most important parameters for approaching an accurate in vivo dosimetry.
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| 36. |
- Tran-Gia, Johannes, et al.
(författare)
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A multicentre and multi-national evaluation of the accuracy of quantitative Lu-177 SPECT/CT imaging performed within the MRTDosimetry project
- 2021
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Ingår i: EJNMMI Physics. - : Springer Science and Business Media LLC. - 2197-7364. ; 8:1
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: Patient-specific dosimetry is required to ensure the safety of molecular radiotherapy and to predict response. Dosimetry involves several steps, the first of which is the determination of the activity of the radiopharmaceutical taken up by an organ/lesion over time. As uncertainties propagate along each of the subsequent steps (integration of the time–activity curve, absorbed dose calculation), establishing a reliable activity quantification is essential. The MRTDosimetry project was a European initiative to bring together expertise in metrology and nuclear medicine research, with one main goal of standardizing quantitative 177Lu SPECT/CT imaging based on a calibration protocol developed and tested in a multicentre inter-comparison. This study presents the setup and results of this comparison exercise. Methods: The inter-comparison included nine SPECT/CT systems. Each site performed a set of three measurements with the same setup (system, acquisition and reconstruction): (1) Determination of an image calibration for conversion from counts to activity concentration (large cylinder phantom), (2) determination of recovery coefficients for partial volume correction (IEC NEMA PET body phantom with sphere inserts), (3) validation of the established quantitative imaging setup using a 3D printed two-organ phantom (ICRP110-based kidney and spleen). In contrast to previous efforts, traceability of the activity measurement was required for each participant, and all participants were asked to calculate uncertainties for their SPECT-based activities. Results: Similar combinations of imaging system and reconstruction lead to similar image calibration factors. The activity ratio results of the anthropomorphic phantom validation demonstrate significant harmonization of quantitative imaging performance between the sites with all sites falling within one standard deviation of the mean values for all inserts. Activity recovery was underestimated for total kidney, spleen, and kidney cortex, while it was overestimated for the medulla. Conclusion: This international comparison exercise demonstrates that harmonization of quantitative SPECT/CT is feasible when following very specific instructions of a dedicated calibration protocol, as developed within the MRTDosimetry project. While quantitative imaging performance demonstrates significant harmonization, an over- and underestimation of the activity recovery highlights the limitations of any partial volume correction in the presence of spill-in and spill-out between two adjacent volumes of interests.
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| 37. |
- Tran-Gia, Johannes, et al.
(författare)
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On the use of solid 133Ba sources as surrogate for liquid 131I in SPECT/CT calibration : a European multi-centre evaluation
- 2023
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Ingår i: EJNMMI Physics. - 2197-7364. ; 10:1
-
Tidskriftsartikel (refereegranskat)abstract
- Introduction: Commissioning, calibration, and quality control procedures for nuclear medicine imaging systems are typically performed using hollow containers filled with radionuclide solutions. This leads to multiple sources of uncertainty, many of which can be overcome by using traceable, sealed, long-lived surrogate sources containing a radionuclide of comparable energies and emission probabilities. This study presents the results of a quantitative SPECT/CT imaging comparison exercise performed within the MRTDosimetry consortium to assess the feasibility of using 133Ba as a surrogate for 131I imaging. Materials and methods: Two sets of four traceable 133Ba sources were produced at two National Metrology Institutes and encapsulated in 3D-printed cylinders (volume range 1.68–107.4 mL). Corresponding hollow cylinders to be filled with liquid 131I and a mounting baseplate for repeatable positioning within a Jaszczak phantom were also produced. A quantitative SPECT/CT imaging comparison exercise was conducted between seven members of the consortium (eight SPECT/CT systems from two major vendors) based on a standardised protocol. Each site had to perform three measurements with the two sets of 133Ba sources and liquid 131I. Results: As anticipated, the 131I pseudo-image calibration factors (cps/MBq) were higher than those for 133Ba for all reconstructions and systems. A site-specific cross-calibration reduced the performance differences between both radionuclides with respect to a cross-calibration based on the ratio of emission probabilities from a median of 12–1.5%. The site-specific cross-calibration method also showed agreement between 133Ba and 131I for all cylinder volumes, which highlights the potential use of 133Ba sources to calculate recovery coefficients for partial volume correction. Conclusion: This comparison exercise demonstrated that traceable solid 133Ba sources can be used as surrogate for liquid 131I imaging. The use of solid surrogate sources could solve the radiation protection problem inherent in the preparation of phantoms with 131I liquid activity solutions as well as reduce the measurement uncertainties in the activity. This is particularly relevant for stability measurements, which have to be carried out at regular intervals.
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| 38. |
- Zimmerman, Brian E, et al.
(författare)
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Multi-centre evaluation of accuracy and reproducibility of planar and SPECT image quantification : An IAEA phantom study
- 2017
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Ingår i: Zeitschrift für Medizinische Physik. - : Elsevier BV. - 1876-4436 .- 0939-3889. ; 27:2, s. 98-112
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Tidskriftsartikel (refereegranskat)abstract
- Accurate quantitation of activity provides the basis for internal dosimetry of targeted radionuclide therapies. This study investigated quantitative imaging capabilities at sites with a variety of experience and equipment and assessed levels of errors in activity quantitation in Single-Photon Emission Computed Tomography (SPECT) and planar imaging. Participants from 9 countries took part in a comparison in which planar, SPECT and SPECT with X ray computed tomography (SPECT-CT) imaging were used to quantify activities of four epoxy-filled cylinders containing 133Ba, which was chosen as a surrogate for 131I. The sources, with nominal volumes of 2, 4, 6 and 23mL, were calibrated for 133Ba activity by the National Institute of Standards and Technology, but the activity was initially unknown to the participants. Imaging was performed in a cylindrical phantom filled with water. Two trials were carried out in which the participants first estimated the activities using their local standard protocols, and then repeated the measurements using a standardized acquisition and analysis protocol. Finally, processing of the imaging data from the second trial was repeated by a single centre using a fixed protocol. In the first trial, the activities were underestimated by about 15% with planar imaging. SPECT with Chang's first order attenuation correction (Chang-AC) and SPECT-CT overestimated the activity by about 10%. The second trial showed moderate improvements in accuracy and variability. Planar imaging was subject to methodological errors, e.g., in the use of a transmission scan for attenuation correction. The use of Chang-AC was subject to variability from the definition of phantom contours. The project demonstrated the need for training and standardized protocols to achieve good levels of quantitative accuracy and precision in a multicentre setting. Absolute quantification of simple objects with no background was possible with the strictest protocol to about 6% with planar imaging and SPECT (with Chang-AC) and within 2% for SPECT-CT.
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| 39. |
- Abu-Ghanem, Yasmin, et al.
(författare)
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Limitations of Available Studies Prevent Reliable Comparison Between Tumour Ablation and Partial Nephrectomy for Patients with Localised Renal Masses : A Systematic Review from the European Association of Urology Renal Cell Cancer Guideline Panel
- 2020
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Ingår i: European Urology Oncology. - : Elsevier. - 2588-9311. ; 3:4, s. 423-442
-
Forskningsöversikt (refereegranskat)abstract
- The European Association of Urology (EAU) Renal Cell Carcinoma (RCC) Guideline Panel performed a protocol-driven systematic review (SR) on thermal ablation (TA) compared with partial nephrectomy (PN) for T1N0M0 renal masses, in order to provide evidence to support its recommendations. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were followed, and only comparative studies published between 2000 and 2019 were included. Twenty-six nonrandomised comparative studies were included, recruiting a total of 167 80 patients. Risk of bias (RoB) assessment revealed high or uncertain RoB across all studies, with the vast majority being retrospective, observational studies with poorly matched controls and short follow-up. Limited data showed TA to be safe, but its long-term oncological effectiveness compared with PN remains uncertain. A quality assessment of pre-existing SRs (n = 11) on the topic, using AMSTAR, revealed that all SRs had low confidence rating, with all but two SRs being rated critically low. In conclusion, the current data are inadequate to make any strong and clear conclusions regarding the clinical effectiveness of TA for treating T1N0M0 renal masses compared with PN. Therefore, TA may be cautiously considered an alternative to PN for T1N0M0 renal masses, but patients must be counselled carefully regarding the prevailing uncertainties. We recommend specific steps to improve the evidence base based on robust primary and secondary studies.Patient summary: In this report, we looked at the literature to determine the effectiveness of thermoablation (TA) in the treatment of small kidney tumours compared with surgical removal. We found that TA could cautiously be offered as an option due to many remaining uncertainties regarding its effectiveness.
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| 40. |
- Agin, Sol, 1989-
(författare)
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Communicating climate action : Combining action repertoires and linguistic repertoires in social movement message construction
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The climate crisis is one of the largest global challenges that humanity has ever faced. Despite the scientific consensus on the threat, action is not occurring on the pace or level needed to stave off the consequences. As climate change is made up by complex and conjoined causes and effects, the issue is also riddled with communicative challenges which those calling for action need to tackle. Climate change communication research has, however, mainly focus on how traditional news media frame the climate change issue and overlooks climate activist and movement groups. This despite these actors being key for shifting public perceptions and public opinion. Although research on other communication actors exist, it is far from extensive and the research field overlooks the publics perceptions of the sender in relation to the construction of climate messages. Through survey data and an experiment, this doctoral thesis explores the public’s inclination towards different protest action repertoires and addresses the research gap in the climate movement message construction. Herein, the actions and words of three subgroups within the larger environmental movement is considered as one part of a larger message whole. The groups chosen action repertoires are viewed as part of the activists’ performed message and the linguistic communication styles created by lexical choices related to emotional appeals are part of the activists’ verbal/textual message. The results indicate that there is much to be gained from adhering to an alignment between lexical choices and action repertoires. Alignment may be key for understanding why some movement subgroups are successful in inspiring certain actions whilst others inspire other actions. Communication-action alignment is a way to approach the interconnectedness of actions and words for complex and abstract issues that require message recipients to construct consonant mental models to break potential cognitive dissonance.
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| 41. |
- Albiges, Laurence, et al.
(författare)
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Updated European Association of Urology Guidelines on Renal Cell Carcinoma : Immune Checkpoint Inhibition Is the New Backbone in First-line Treatment of Metastatic Clear-cell Renal Cell Carcinoma
- 2019
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Ingår i: European Urology. - : Elsevier BV. - 0302-2838 .- 1873-7560. ; 76:2, s. 151-156
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Tidskriftsartikel (refereegranskat)abstract
- Recent randomised trials have demonstrated a survival benefit for a front-line ipilimumab and nivolumab combination therapy, and pembrolizumab and axitinib combination therapy in metastatic clear-cell renal cell carcinoma. The European Association of Urology Guidelines Panel has updated its recommendations based on these studies. Patient summary: Pembrolizumab plus axitinib is a new standard of care for patients diagnosed with kidney cancer spread outside the kidney and who did not receive any prior treatment for their cancer (treatment naïve). This applies to all risk groups as determined by the International Metastatic Renal Cell Carcinoma Database Consortium criteria.
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| 42. |
- Almquist, Helén, et al.
(författare)
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Quantitative SPECT by attenuation correction of the projection set using transmission data: evaluation of a method
- 1990
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Ingår i: European Journal Of Nuclear Medicine. - 1432-105X. ; 16:8-10, s. 587-594
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Tidskriftsartikel (refereegranskat)abstract
- A method for measuring attenuation coefficients in single-photon emission tomography (SPECT) is described and evaluated, together with a method for attenuation correction using these measured attenuation coefficients. Build-up, caused by scattered photons, is corrected for by a simple substitution in the algorithms. Transmission studies are performed with a 99mTc- or 57Co flood source, and emission phantom studies with 99mTc line sources. The method is evaluated with variable but well-defined phantoms. The result is accurate attenuation coefficients for different densities, dimensions and geometries, and an accuracy of corrected emission activities of better than +/- 10% in most cases. The present limitations of the method for attenuation correction are discussed.
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| 43. |
- Almqvist, Monica, et al.
(författare)
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European Medical Imaging Technology Training, EMIT – ett prisbelönt EU-utbildningsprojekt
- 2005
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Ingår i: [Host publication title missing].
-
Konferensbidrag (refereegranskat)abstract
- I ett sameuropeiskt Leonardo da Vinci-projekt har utvecklats ett internationellt utbildnings- och praktikpa- ket för blivande sjukhusfysiker [1-3]. Utbildningspaketet innehåller praktiska och kliniska övningsuppgifter där delta- garna tränas i för en sjukhusfysiker vanligt förekommande arbetsuppgifter. Målet har varit att det skall ge sjukhusfysi- kern den praktiska kompetens som krävs av det europeiska regelverket inom ämnesområdena magnetresonans (MRI), ultraljud, röntgendiagnostik, nuklearmedicin och strålbe- handling. Utbildningsmaterialet är webbaserat med en stor bilddata- bas och används redan i nära 70 länder runt om i världen. EMIT-projektet (European Medical Imaging Technology Training) belönades i december 2004 med det första Leonar- do da Vinci priset som delades ut till de tre bästa av totalt 4000 EU-projekt inom praktisk yrkesrelaterad utbildning. I projektet har vi konfronterats med den pedagogiska ut- maningen att förmedla praktisk kunskap, i sjukhusmiljöer med mycket olika förutsättningar beroende på vilket land deltagarna arbetar i. En omöjlig uppgift kan tyckas, men eftersom materialet är sammanställt av några av Europas starkaste forsknings- och utbildningsgrupper inom respekti- ve område så har det visat sig vara en stor tillgång och varje användare utnyttjar materialet efter sina egna behov. En an- nan erfarenhet är samarbetet över nationsgränser där vi har utnyttjat och konfronterats med likheter och oliktänkande inte minst vad gäller pedagogik och didaktik. Vi har dessut- om fått ett stort kontaktnät och många goda vänner. Den här presentationen beskriver delar av utbildningspaketet och erfarenheter av samarbetsprojektet.
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| 44. |
- Arlig, A, et al.
(författare)
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Attenuation correction in quantitative SPECT of cerebral blood flow: a Monte Carlo study
- 2000
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Ingår i: Physics in Medicine and Biology. - : IOP Publishing. - 1361-6560 .- 0031-9155. ; 45:12, s. 3847-3859
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Tidskriftsartikel (refereegranskat)abstract
- Monte Carlo simulation has been used to produce projections from a voxel-based brain phantom, simulating a 99mTc-HMPAO single photon emission computed tomography (SPECT) brain investigation. For comparison, projections free from the effects of attenuation and scattering were also simulated, giving ideal transaxial images after reconstruction. Three methods of attenuation correction were studied: (a) a pre-processing method, (b) a post-processing uniform method and (c) a post-processing non-uniform method using a density map. The accuracy of these methods was estimated by comparison of the reconstructed images with the ideal images using the normalized mean square error, NMSE, and quantitative values of the regional cerebral blood flow, rCBF. A minimum NMSE was achieved for the effective linear attenuation coefficient mu(eff) = 0.07 (0.09) cm(-1) for the uniform(pre) method, the effective mass attenuation coefficient mu(eff)/rho = 0.08 (0.10) cm2 g(-1) for the uniform(post) method and mu(eff)/rho = 0.12 (0.13) cm2 g(-1) for the non-uniform(post) method. Values in parentheses represent the case of dual-window scatter correction. The non-uniform(post) method performed better, as measured by the NMSE, both with and without scatter correction. Furthermore, the non-uniform(post) method gave, on average, more accurate rCBF values. Although the difference in rCBF accuracy was small between the various methods, the same method should be used for patient studies as for the reference material.
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| 45. |
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| 46. |
- Bartosik, Jolanta, et al.
(författare)
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Subendocardial versus transmural ischaemia in myocardial perfusion SPECT - a Monte Carlo study
- 2006
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Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961. ; 26:6, s. 343-350
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Tidskriftsartikel (refereegranskat)abstract
- Myocardial perfusion imaging with single-photon emission computed tomography (SPECT) is useful for the evaluation of patients with known or suspected coronary artery disease. Parameters of interest are the reduction in the blood perfusion (severity) and the lesion volume (extent). The aim of this study was to evaluate these parameters, as calculated by automatic quantification software, for different cases of subendocardial and transmural myocardial lesions. Methods A computer phantom was used to simulate 32 male patients with different defect locations and activity uptakes, which were based on clinical patient studies. The Monte Carlo program SIMIND was used to simulate realistic SPECT projections which were reconstructed to give short-axis images, analysed by the AutoQUANT program using the same procedure as for a real patient. Results The results showed a disparity between the quantification of transmural and subendocardial lesions with the same lesion activity uptake reduction and this could be confirmed by visual interpretation. Neither the parameters given by the quantification program nor visual interpretation could distinguish between the transmural lesions and the subendocardial lesions with activity uptake reduction twice as high as in the corresponding transmural lesions. Conclusion Transmural lesions and the corresponding subendocardial lesions with the same activity uptake reduction could be separated by the quantification software for SPECT imaging and visual analysis. The subendocardial lesions with activity uptake reduction twice as high as in the corresponding transmural lesions could not be differentiated neither by the quantification software nor by visual interpretation. Thus these lesions will get the same scoring when analysed by the AutoQUANT program.
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| 47. |
- Bergerot, Cristiane Decat, et al.
(författare)
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Frustration and distress during treatment for advanced renal cell carcinoma
- 2018
-
Ingår i: Journal of Clinical Oncology. - Univ Fed Sao Paulo UNIFESP, Sao Paulo, Brazil. KCCure, Alexandria, VA USA. City Hope Comprehens Canc Ctr, Monrovia, CA USA. Duke Univ, Durham, NC USA. Johns Hopkins Univ, Sidney Kimmel Comprehens Canc Ctr, Baltimore, MD USA. Univ Texas MD Anderson Canc Ctr, Houston, TX 77030 USA. Umea Univ, Umea, Sweden. Netherlands Canc Inst, Amsterdam, Netherlands. City Hope Comprehens Canc Ctr, Duarte, CA USA. Ludwig Maximilians Univ Munchen, Univ Hosp Munich Grosshadern, Munich, Germany. City Hope Natl Med Ctr, Duarte, CA USA. : AMER SOC CLINICAL ONCOLOGY. - 0732-183X .- 1527-7755. ; 36:34
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 48. |
- Bergerot, Cristiane Decat, et al.
(författare)
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Sources of Frustration Among Patients Diagnosed With Renal Cell Carcinoma
- 2019
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Ingår i: Frontiers in Oncology. - : Frontiers Media S.A.. - 2234-943X. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- Despite numerous therapeutic advances in renal cell carcinoma (RCC), little is known about patients' perspectives on cancer care. An international survey was conducted to identify points of frustration associated with cancer care reported by patients with RCC. Data were obtained from an online survey, conducted from April 1 to June 15, 2017, through social media and patient networking platforms. This survey obtained baseline demographic, clinicopathologic, and treatment-related information. Open-ended questions accessed sources of frustration in cancer-related care and patients' suggestions for amelioration. Responses were categorized and reviewed by independent reviewers. A qualitative analysis was performed and the Kruskal-Wallis test was used to define associations between baseline characteristics and sources of frustration. Among 450 patients surveyed, 71.5% reported sources of frustration, classified as either emotional (48.4%) or practical (23.1%). The most common were fear of recurrence/progression (15.8%), distrust of their cancer care system (12.9%), and lack of appropriate information (9.8%). Female gender and non-clear cell histology were associated with both types of frustration, and older age was linked to practical sources of frustration. Patients suggested solutions included greater compassion among health care practitioners (20.7%), better access to information (15.1%) and research to improve their chances of being cured (14.7%). Sources of frustration related to emotional and practical causes were identified amongst patients with RCC. Certain demographic and clinical characteristics were associated with more sources of frustration. This study provides the first characterization of specific ways to improve the patient experience by addressing common frustrations.
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| 49. |
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| 50. |
- Bex, Axel, et al.
(författare)
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Updated European Association of Urology Guidelines for Cytoreductive Nephrectomy in Patients with Synchronous Metastatic Clear-cell Renal Cell Carcinoma
- 2018
-
Ingår i: European Urology. - : Elsevier. - 0302-2838 .- 1873-7560. ; 74:6, s. 805-809
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Tidskriftsartikel (refereegranskat)abstract
- Cytoreductive nephrectomy (CN) has been the standard of care in patients with metastatic clear-cell renal cancer who present with the tumour in place. The CARMENA trial compared systemic therapy alone with CN followed by systemic therapy. This article outlines the new guidelines based on these data.Patient summary: The CARMENA trial demonstrates that immediate cytoreductive nephrectomy should no longer be considered the standard of care in patients diagnosed with intermediate and poor risk metastatic renal cell carcinoma when medical treatment is required. However, the psychological burden poor risk patients experience hearing that removal of their primary tumour will not be beneficial, should be carefully considered.
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