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The nuclear physics and chemical properties of technetium-99m are reviewed. The review of basic nuclear physics includes: classification of nuclides, nuclear stability, production of radionuclides, artificial production of molybdenum-99, production of technetium 99m and -99Mo-99mTc generators. The discussion of the chemistry of technetium includes a profile of several -99mCc-labeled radiopharmaceuticals.
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This chapter is a primer on the physics of radionuclide detection, flow physiology, and methods of in vivo evaluation of myocardial metabolism and intercavitary flow by noninvasive methods of intravenous isotope injection. This summary presents key concepts for the application of currently available instrumentation as well as future directions of nuclear cardiology. 1. Quantitative information is obtained in nuclear cardiology at the cost of high resolution imaging for two reasons: (a) the intrinsic resolution of the detecting systems is limited by available technology, and (b) the statistics required to achieve a high resolution image necessitate doses and imaging times far in excess of those which can be tolerated. Image resolution for both projection images as well as transverse sections are limited to the range of 5 to 20 mm, depending upon the configuration and instrument involved. 2. The second important concept is the fact that nuclear cardiology gives quantitative information regarding the amount of radiopharmaceutical which has accumulated in or is flowing through the cardiovascular system. This information allows one to deduce the dynamics of flow as well as actual metabolic rates. 3. The major emphasis for future work might well lie in the multiple transverse section imaging of the myocardium using both rotating and static devices. The key feature of this approach is the fact that the volume of interest can be localized and actual concentrations of radiopharmaceuticals can be measured by external detection using reconstruction tomography images. 4. Quantitative data on the distribution of a metabolite which accumulates in the myocardium is of little value if regional blood flow is not also known. 5. Finally, it is shown in this chapter that specific volume flow can be evaluated using short half-life isotopes and equations derived from the principle of conservation of mass. In principle it is now possible to obtain quantitative values delineating endo- and epicardial flow for the heart of man without invasive catheterization or high radiation doses. These procedures involve constant inhalation of carbon dioxide labeled with 15O which converts to labeled water and can be used for evaluating myocardial perfusion; bolus injection of 82Rb, a short half-life analogue of potassium, for repeated (every 5 min) imaging of the evolution of myocardial infarction size; evaluation of the accumulation of labeled fatty acids, amino acids, and sugars in the myocarium; presentation of images which reflect the magnitude of ejection fraction; and noninvasive evaluation of cardiac shunts. It is now possible to perform on the same patient during a few hours the following studies of myocardium: cation perfusion evaluation; water perfusion; uptake of fatty acids, amino acids, and glucose; oxygen utilization of the myocardium; and even measurement of the quantity of lung water. We now have the tools and methods to evaluate the in vivo biochemistry of the ischemic, 128 infarcting, repairing, and hypertrophic myocardium.
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The TRIUMF 520 MeV H- cyclotron produces intense beams of protons, pions and muons supporting basic research in nuclear, particle and solid-state physics, nuclear chemistry and biomedicine, and applied research in electromagnetic breeding of nuclear fuel, proton radiography, radioisotope production and cancer treatment.
The multi-disciplinary role of intermediate energy proton accelerators in pure and applied nuclear physics is discussed with particular reference to the experimental programmes at LAMPF (Los Alamos Meson Physics Facility) and SIN (Swiss Institute for Nuclear Research, Zurich).
Modern radionuclide bone scanning has introduced a new concept in physiologic and anatomic diagnostic imaging to general medicine. As otolaryngologists must diagnose and treat disease in relation to the bony and/or cartilaginous supporting structures of the neurocranium and upper airway, this modality should be included in the otolaryngologist's diagnostic armamentarium. It is the purpose of this manuscript to study the specific applications of bone scanning to our specialty at this time, based on clinical experience over the past three years. This thesis describes the development of bone scanning in general (history of nuclear medicine and nuclear physics; history of bone scanning in particular). General concepts in nuclear medicine are then presented; these include a discussion of nuclear semantics, principles of radioactive emmissions, the properties 99mTc as a radionuclide, and the tracer principle. On the basis of these general concepts, specific concepts in bone scanning are then brought forth. The physiology of bone and the action of the bone scan agents is presented. Further discussion considers the availability and production of the bone scan agent, patient factors, the gamma camera, the triphasic bone scan and the ultimate diagnostic principle of the bone scan. Clinical applications of bone scanning in otolaryngology are then presented in three sections. Proven areas of application include the evaluation of malignant tumors of the head and neck, the diagnosis of temporomandibular joint disorders, the diagnosis of facial fractures, the evaluation of osteomyelitis, nuclear medicine imaging of the larynx, and the assessment of systemic disease. Areas of adjunctive or supplementary value are also noted, such as diagnostic imaging of meningioma. Finally, areas of marginal value in the application of bone scanning are described.
Neutron production from targets of Be, C, Mo, Cu, Ta and Au bombarded with deuterons of 16, 33 and 50 MeV has been studied at the isochronous cyclotron at Louvain-la-Neuve. Neutron spectra were measured by the time of flight method. The yields of neutrons and gamma rays were also measured, and the greatest ratio of neutrons to gamma rays in the forward direction was found to occur with 50 MeV deuterons on a Be target. The angular distribution of neutrons from Be was measured at 16, 33 and 50 MeV, and neutron spectra were measured as function of angle with 50 MeV deuterons on Be.
The dose given to a polythene energy absorber in the radiation field from a 14 MeV neutron generator has been measured calorimetrically. The calorimeter was calibrated by giving the energy absorber a known dose of gamma-rays. The dose measured in this way was compared with that determined with a polythene-ethylene ionization chamber, and the two results agreed to better than 1%, though the estimated uncertainties on the calorimeter and ionization chamber results were each about 4%. This result can be used to determine a value of the ratio Wn/We, for 14 MeV neutrons in ethylene, where Wn is the W value for the charged particles generated in the neutron field in ethylene, and We is the W value for electrons in the same gas. The measured value of Wn/We was found to be 1.07 plus or minus 3.9%. The significance of the 'thermal defect' in polythene is discussed.