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Física da Radiação, 1º semestre, IST, 2010/2011 1 Radiopharmacology

Diogo Ferreira, MSc student in Biomedical Engineering, Instituto Superior Técnico, student no58548

Abstract Nuclear Medicine is the branch of medicine concerned with the use of radio-nuclides in the study and the diagnosis of diseases, eg. the assessment of organ function, detection and treatment of some diseases or monitoring of treatment’s effects. It provides physiological (not available from other imaging modalities) and diagnostic information. In the other hand, it uses very small amounts of radioactive material (radiopharmaceuticals, RP) that is introduced into the body and acts as a tracer. Information obtained using nuclear medicine techniques is more comprehensive than other imaging procedures because it demonstrates organ function, not just his structure. The result: many diseases (eg, cancer) may be diagnosed much earlier. In this article, will be discussed questions such as “What are RPs?”, “What is the difference between gamma-decay and beta-decay for nuclear medicine?”, “What kind of RPs are there in therapy or diagnosis?”, “How must be the ideal RP?”, “How can we produce RPs?” or “How can we detect the RPs using techniques, as PET?”. Finally, the bone-seeking therapeutic RP will be discussed. In fact, this technique is used on the basis of radionuclide’s particulate emissions (primarily low to intermediate beta emission). Outline 0. 1. 2. 3. 4. 5. 6. 7. 8. 9. Nuclear Medicine Radioactive processes and interaction with matter Radiopharmaceuticals, Reactor-Produced Radionuclides and Generator systems Therapeutic RPs Diagnosis RPs Physical Principles of PET PET RPs Bone-seeking therapeutic RPs Development of new RPs References imaging of the whole body based on certain cellular receptors or functions, as Ga-67 scan, used in PET scan, [1,14]. Diagnostic tests in nuclear medicine exploit the way that the body handles substances differently when there is disease or pathology present. The radionuclide introduced into the body is often chemically bound to a complex that acts characteristically within the body; this is commonly known as a tracer. In the presence of disease, a tracer will often be distributed around the body and/or processed differently. For example, the ligand methylenediphosphonate (MDP) can be preferentially taken up by bone. By chemically attaching Tc99m to MDP, radioactivity can be transported and attached to bone via the hydroxyapatite for imaging. Any increased physiological function, such as due to a fracture in the bone, will usually mean increased concentration of the tracer, [14]. Another example is the PET scan of Alzheimer’s disease. PET images show the

Development 0. Nuclear Medicine

Nuclear Medicine (NM) is a branch or specialty of medicine that uses radionuclides and relies on the process of radioactive decay in the diagnosis and treatment of diseases. Elemental radionuclides are combined with other elements to form chemical compounds to form radiopharmaceuticals (or RPs). In NM imaging, RPs are taken internally and, then, external detectors capture and form images from the emitted radiation by the RPs. There are several techniques of diagnosis: scintigraphy (for 2D images), SPECT (for 3D images) and PET (2D/3D images, as we well discuss later). NM tests differ from most other imaging modalities because it des not show just the system anatomy. Moreover, its studies are generally more tissue specific than those in conventional imaging (as radiography or MRI). In addition, there are NM studies that allow

Física da Radiação, 1º semestre, IST, 2010/2011 2 Radiopharmacology metabolic degeneration of the brain of a patient with Alzheimer's as it progressively reduces brain function. In the early stages of the disease, limited areas of the brain are dysfunctional, but in late stages of Alzheimer's, larger brain areas are affected. The structures that are...
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