| 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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