| 1. |
- 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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| 2. |
- Gunnarsson, Mikael, et al.
(författare)
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Principles behind Computed Tomography (CT)
- 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 use of Computed tomography (CT) for anatomical information in a combination with the SPECT system has in many ways added substantial information to many nuclear medicine imaging procedures. The information from the CT system can provide information on the location of lesions and can be used for attenuation correction. Modern SPECT/CT and PET/CT today have CT scanners that provide diagnostic quality. This chapter provides the principles behind the X-ray imaging and in particular CT. It describes scanner configurations and components for a typical CT system and how data are acquired. Also, a short description of dual-energy systems that provide additional information is included. Iterative reconstruction of image, and the definition of the Hounsfield unit is discussed together with how different factors affect the image quality. A part of the chapter also discusses CT dosimetry and how the absorbed doses can be measured, quantified, and possibly be reduced. A section also discusses different types of artefacts in the images caused by, for example, metals, respiratory movements, and beam hardening.
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| 3. |
- Gustafsson, Johan, et al.
(författare)
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Image Processing
- 2022
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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 ; I, s. 197-219
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Bokkapitel (refereegranskat)abstract
- Image processing provides tools for image enhancement and extraction of information from images. Modification of the colour table allows for amplification of the contrast in certain pixel-value intervals while the contrast is suppressed in other intervals. This can in turn be used to selectively enhance the displayed image in intervals of special importance to the current problem. One of the most important conflicts in imaging is the trade-off between a high signal-to-noise-ratio (SNR) and a good spatial resolution. Low-pass filtering can be used to improve the SNR at the expense of spatial resolution. Likewise, high-pass filtering can be used to enhance edges but tends to be noise sensitive. Another important kind of operations is spatial transformations, for example, scaling, translation, and rotation. The discrete nature of digital images makes the application of such operations dependent on the use of interpolation. There are different interpolation methods that vary in accuracy and computational burden. Lastly, many applications are dependent on image segmentation. The most common segmentation method is manual delineation, but there are a number of automatic and semi-automatic methods that may be used to save time and improve reproducibility. While the presentation of the subject is by no means complete, the hope is that it will serve as an introduction to the most important image-processing techniques used in nuclear medicine.
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| 4. |
- Jönsson, Bo-Anders, et al.
(författare)
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The History of Nuclear Medicine
- 2022. - 1st Edition
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Ingår i: Handbook of Nuclear Medicine and Molecular Imaging for Physicists : Instrumentation and Imaging Procedures - Instrumentation and Imaging Procedures. - New York : CRC Press. - 9781138593268 - 9781032058689 - 9780429489556 ; 1:1, s. 1-14
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Bokkapitel (refereegranskat)abstract
- The chapter provides a historic overview of the research in physics and chemistry for the development of radionuclides, radiopharmaceuticals, and instrumentation which have had a major impact for the today’s status of nuclear medicine. During the first half of the 20th century in particular, a number of researchers with relevance to the development of nuclear medicine have been awarded the Nobel Prize. After Röntgen’s and Becquerel's fantastic discoveries, 1885 and 1886 respectively, the first three decades were characterized by a systematic research that resulted in a growing use of ionizing radiation in medicine. The inventions of the cyclotron in the 1930s and the fission reactor in the early 1940s resulted into production of a variety of radionuclides. The development of the 99Mo-99Tcm-generator 1957, initiated a successive expansion of developed radiopharmaceuticals. The 1950s was the decade when the fundamental imaging devices, the scintigraph and the Anger camera, was invented and became outstanding workhorses during years. The decades to come, 1970-1990, led to further instrumental development with tomographic techniques, SPECT and PET, as well as a growing interest in radioimmunology and internal dosimetry. The last decade’s research has led into an improved imaging by multi-modality systems, SPECT/CT and PET/CT, sophisticated molecular imaging, and individual patient dosimetry. Nuclear medicine is cutting-edge and will remain a significant field in diagnostic imaging and radiation therapy. The medical physicist has an important role to play for further development – to be the expert link between radiation physics, imaging technology and medical applications.
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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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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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| 7. |
- Rääf, Christopher, et al.
(författare)
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Gamma Spectrometry
- 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
- Gamma spectrometry primarily is used for identification and quantification of gamma-emitting radionuclides present in samples collected from a specific environment. The objective is often to determine, with a certain confidence, whether the activity concentration of the present gamma emitters exceed some reference level: for example, a criterion for the highest level of impurity of gamma emitters in a radiopharmaceutical solution. Although medical physicists within nuclear medicine applications may often rely on the delivered radioactive solutions fulfilling quality criteria in terms of specified radionuclide content, it may nevertheless still be important to have access to, and sufficiently master, gamma-spectrometric assessments to make independent quality assurances. In this chapter a brief overview of gamma-spectrometric assessment is presented, with the aim of obtaining an understanding of the physical and computational fundamentals of this measurement procedure and the quality parameters used to characterize the performance of the assessment method. What prerequisites exist for setting up a gamma-spectrometry system, and what factors influence the precision and accuracy of the method? Furthermore, this chapter presents the basic procedures for maintaining a sufficient quality in the performance of the gamma spectrometry and also provides some examples of evaluation of gamma spectra.
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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. |
- Sjögreen Gleisner, Katarina, et al.
(författare)
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Activity Quantification from Planar Images
- 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
- Planar imaging was for a long time the most-used technique for image-based activity quantification. Owing to its simplicity and speed, the possibility to acquire dynamic image sequences, and to generate whole-body images at a reasonable acquisition time, it is still frequently used in nuclear-medicine imaging. Today, planar imaging is most commonly used for diagnostic examinations with qualitative or semi-quantitative evaluation but is also performed for patients receiving radionuclide therapy. Activity quantification may then be applied to estimate the absorbed doses delivered to organs and tumours. It is well recognized that planar images suffer from the superposition of counts from activity located at different depths in the patient and that generally quantitative SPECT is superior for activity quantification. However, the techniques for planar-based activity quantification preceded and, in parts, formed the basis for the subsequent development of quantification methods from tomographic SPECT images, and these techniques still carry value in terms of understanding the process with which planar image projections are formed. Notably, also when acquisition is made in SPECT mode, the raw image data consist of a set of planar projections. Moreover, planar-based activity quantification is still used, for example, to estimate the total-body absorbed dose, and in combination with SPECT-based activity quantification in so-called hybrid planar/SPECT methods.
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