Physics
Radionuclide Imaging Techniques
Radionuclide imaging techniques involve the use of radioactive substances to create images of the body's internal structures and functions. These techniques, such as positron emission tomography (PET) and single photon emission computed tomography (SPECT), are valuable tools in diagnosing and monitoring various medical conditions, including cancer, heart disease, and neurological disorders. They provide detailed information about organ function and can help guide treatment decisions.
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11 Key excerpts on "Radionuclide Imaging Techniques"
eBook - PDF- Walter D. Loveland, David J. Morrissey, Glenn T. Seaborg(Authors)
- 2017(Publication Date)
- Wiley(Publisher)
93 4 Nuclear Medicine 4.1 Introduction The most rapidly expanding area of radionuclide use is in nuclear medicine. Nuclear medicine deals with the use of radiation and radioactivity to diagnose and treat disease. The two principal areas of endeavor, diagnosis and ther- apy, involve different methods and considerations for radioactivity use. (As an aside, we note that radiolabeled drugs that are given to patients are called radiopharmaceuticals.) Recent work in this area has focused on developing combinations of two isotopes in one delivery system: one isotope provides a therapy function and another isotope provides a diagnostic function, called theranostics. In diagnosis (imaging) emitted radiation from injected radionuclides is detected by special detectors (cameras) to give images of the body. A list of radionuclides commonly used in diagnosis is shown in Tables 4.1 and 4.2. At present, most nuclear medicine procedures (>90%) use either 99 Tc m or one of the iodine isotopes. Most diagnostic use of radionuclides is for imaging of specific organs, bones, or tissue. Typical administered quantities of radionu- clides are 1–30mCi for adults. Nuclides used for imaging should emit photons with an energy between 100 and 200 keV, which have small decay branches for particle emission (to minimize radiation damage) and have a half-life that is ∼1.5 times the duration of the test procedure and be inexpensive and readily available. 99 Tc m is used in more than 80% of nuclear medicine imaging because its 143 keV γ-rays produce excellent images with today’s gamma cameras, and it has a convenient 6 h half-life. In therapy, radionuclides are injected into the body and concentrated in the organ of choice and damage the tissue. Nuclear medicine combines nuclear and radiochemistry, pharmacy, medicine, and radiation biology in a challenging and satisfying career.
eBook - PDF- Luca Saba, Warren M. Rozen, Alberto Alonso-Burgos, Diego Ribuffo, Luca Saba, Warren M. Rozen, Alberto Alonso-Burgos, Diego Ribuffo(Authors)
- 2018(Publication Date)
- CRC Press(Publisher)
The mechanism of localisation of a radiopharmaceutical in a particular target organ depends on different processes as antigen–antibody reactions, physicochem-ical adsorption or chemisorption, receptor site binding, and transport of a chemical species across a cell membrane and into the cell. The biological functions can be displayed as images, numerical data, or time–activity curves. The different uptake of the radiopharmaceutical can reveal the normal or altered state of tissue metabolism or specific function of an organ system. Another important use is to predict the effects of surgery and assess changes since treatment. 4.2.2 N UCLEAR M EDICINE I NSTRUMENTATION 4.2.2.1 Gamma Camera Detector 4.2.2.1.1 Introduction The purpose of nuclear medicine imaging is to obtain a picture of the distribution of a radiophar-maceutical within the body after the administration and its metabolism in the patient. In order to get images, it is necessary to detect the radiation emitted by the radionuclide. Alpha particles and electrons ( β± particles, auger and conversion electrons) are not used for imaging because they can-not penetrate more than a few millimetres of tissue. Gamma ( γ ) radiation is non-particulate and penetrating, making it useful for diagnostic imaging purposes. Gamma ray in the approximate energy range of 60–600 keV (or annihilation photons, 511 keV in PET) is sufficiently penetrating in body tissues to be detected by an external radiation detector used in diagnostic nuclear medicine. There are two types of nuclear imaging methods: single-photon imaging and PET. The distinc-tion between these two imaging modalities is based on the physical properties of the radioisotopes used for imaging. Radioisotopes emitting single γ -ray are used to obtaine single-photon imaging (Table 4.2). The most widely used single-photon emitters include 99m Tc, 201 Tl, and 123 I.
eBook - PDF- M Flower(Author)
- 2016(Publication Date)
- CRC Press(Publisher)
In both techniques, images of the biodistribution of radionuclide-labelled agents in the body are formed. These agents, known as radiopharmaceuticals, are designed to determine the physiological function of individual tissues or organs in the body. The dis-tribution of these agents within the body is determined by route of administration and by such factors as blood flow, blood volume and a variety of metabolic processes. The first use of a radioisotope, 131 I, to investigate thyroid disease was carried out in the late 1930s. Early developments in imaging equipment include the production of the recti-linear scanner and the scintillation camera during the 1950s. Both these devices became widely available in the mid-1960s. The rectilinear scanner and similar devices are no longer widely used since the Anger/gamma camera has become readily available – this is now the instrument of choice for single-photon imaging. Also in the early 1950s, the first devices for the detection of annihilation photons from positron emitters were used clinically. This technology has developed rapidly in the 1990s and, with the increased availability of pos-itron-emitting radionuclides from cyclotrons, there is now a steady growth in the number of hospitals performing PET. Unlike X-ray imaging, where both the emission and detection 5.9.10.5 Applications in Neurology .................................................................... 322 5.9.10.6 Applications in Clinical Research ........................................................ 322 5.10 Performance Assessment and Quality Control of Radioisotope Imaging Equipment ........................................................................................................... 323 5.10.1 Flood-Field Uniformity ....................................................................................... 325 5.10.2 Spatial Resolution .................................................................................................
eBook - PDF- Shan Xiang Wang, Adam de la Zerda(Authors)
- 2022(Publication Date)
- Wiley(Publisher)
Biochips and Medical Imaging, First Edition. Adam de la Zerda and Shan Xiang Wang. © 2022 John Wiley & Sons, Inc. Published 2022 by John Wiley & Sons, Inc. 295 14.1 Radioactivity A radionuclide is an atom with an unstable nucleus, which has excess energy that can be trans- ferred to either a newly created radiation particle or an electron. During this process of radioactive decay, the radionuclide also emits gamma rays and/or subatomic particles. Radionuclide imaging, or nuclear imaging, uses radionuclides and their radioactive decay to produce images of tissues (Figure 14.1), using either positron emission tomography (PET) or single photon emission computed tomography (SPECT). Unlike MRI, for which the body naturally produces a good signal without administration of an external contrast agent, nuclear imaging requires the injection of contrast agents or imaging agents since the body naturally is not radioactive enough to produce a detectable and specific signal. 14.1.1 Gamma Decay An atom or atom within a molecule that is in an unstable state (i.e. a radionuclide) can undergo three different types of radioactive decay: alpha, beta, or gamma. Beta and gamma decay are appli- cable for nuclear imaging. During gamma decay (Figure 14.2), nucleons rearrange themselves to a less energetic, more stable configuration, giving off electromagnetic energy in the form of high- energy (i.e. very short wavelength) gamma photons. For gamma imaging, a metastable parent atom is required, i.e. the atomic number (number of protons) Z does not change during decay: A z A z X X , where X is an atom, A is the mass number (number of neutrons and protons), and Z is the atomic number (number of protons). When a metastable atom undergoes gamma decay, the mass number (i.e. total number of protons and neutrons) does not change, but one electron moves from one shell to another, and thus emits high-energy gamma rays on the order of several keV.
eBook - PDFReviews Of Accelerator Science And Technology - Volume 2: Medical Applications Of Accelerators
Volume 2: Medical Applications of Accelerators
- Alexander Wu Chao, Weiren Chou(Authors)
- 2009(Publication Date)
- World Scientific(Publisher)
The advent of clinical PET for cancer diagnosis makes use of sophisticated tracers to unravel cancer biology. 4.2. Radionuclides for imaging Nuclear medicine imaging differs from other types of radiological imaging, in that the radiotracers used in nuclear medicine map out the function of an organ system or metabolic pathway and, thus, imaging the concentration of these agents in the body can reveal the integrity of these systems or pathways. This is the basis for the unique infor-mation that a nuclear medicine scan (described in Table 3) provides with various scanning proce-dures for the various organ/functional systems of the body. Table 3. Typical radioisotopes and their uses for imaging. Radioisotope Half-life Uses Technetium-99m 6 h derived from 99 Mo parent 66 h Used to image the skeleton and heart muscle, in particular; but also for the brain, thyroid, lungs (perfusion and ventilation), liver, spleen, kidneys (structure and filtration rate), gall bladder, bone marrow, salivary and lachrymal glands, heart blood pool, infection and numerous specialist medical studies. Cobalt-57 272 d Used as a marker to estimate organ size and for in vitro diagnostic kits. Gallium-67 78 h Used for tumor imaging and localization of inflammatory lesions (infections). Indium-111 67 h Used for specialist diagnostic studies, e.g. brain, infection, and colon transit studies. Iodine-123 13 h Increasingly used for diagnosis of thyroid function, it is a gamma emitter without the beta radiation of 131 I. Krypton-81m 13 s from 81 Rb 4.6 h 81m Kr gas can yield functional images of pulmonary ventilation, e.g. in asthmatic patients, and for the early diagnosis of lung diseases and function. Rubidium-82 65 h Convenient PET agent for myocardial perfusion imaging. Strontium-92 25 d Used as the “parent” in a generator to produce 82 Rb. Thallium-201 73 h Used for diagnosis of coronary artery disease and other heart conditions, such as heart muscle death and for location of low-grade lymphomas.
eBook - PDF- William D. Leslie, I. David Greenberg(Authors)
- 2003(Publication Date)
- CRC Press(Publisher)
Comparative Imaging and the Role of Nuclear Medicine Classical radiology had been rooted in studies of structure. That is changing as physiological images and sometimes measurements are being made with CT and, especially, functional MRI and spectroscopy. Nevertheless, from first principles it will be difficult to match the power of nuclear medicine in, for example, detecting receptor binding. Another decisive advantage of nuclear medicine is its capacity to be used in whole body imaging. The idea of whole body MRI “screening” has been mooted but its value is speculative and it would be expensive. In contrast, nuclear medicine body imaging is unsurpassed in the search for disease not causing local symptoms, such as metastatic tumor spread or occult infections. As we have seen, the first technique which allowed us to “see” the inside of the human body was X-ray imaging. Very soon, however, it was followed by other techniques such as nuclear medicine, ultrasound (US), CT and, more recendy, MRI. In order to realize the possibilities and limitations of each technique and to better understand their place in the diagnostic process it is important to consider the physical process that each modality employs. In differing degrees most methods are capable of anatomical and functional imaging and almost all techniques can examine both when special contrast agents or other modifications are used. Attenuation of electromagnetic radiation (which depends on the electron density of the material) is the physical principle used in X-ray imaging or CT. The resulting images represent differences in transmission of the X-rays (a form of electromagnetic radiation) or, indirectly, differences in their attenuation by tissues and, thereby, the anatomy of the subject. If a special contrast agent is introduced any images made will reflect the distribution of this agent and such images may depict a particular organs function.
eBook - PDFNuclear Physics 2
Radiochronometers and Radiopharmaceuticals
- Ibrahima Sakho(Author)
- 2024(Publication Date)
- Wiley-ISTE(Publisher)
The radiotracer acts as a microemitter of gamma rays, which can be detected using devices such as gamma cameras [OPE 07]. Once injected into the bloodstream during various imaging tests (PET, scintigraphy, etc.), the tracer can be visualized in the patient’s body. By binding to different organs, the tracer can be used to analyze organ function [INS 10]. Radiotracers are defined as radiopharmaceuticals (RPPs). A drug is defined as any substance or composition presented as having curative or preventive properties with regards to human or animal diseases. It is also defined as any product that can be administered to humans or animals, with a view to establishing a medical diagnosis or to restoring, correcting or modifying organic functions [PAY 08]. In addition, a RPP, the concept of which first appeared in 1965, is defined as “a drug whose active principle is based on the properties of the radioactive emission of a radioelement” [BOU 17, MAN 20]. RPPs are generally used for diagnostic purposes (85% of cases), and more rarely for therapeutic purposes (15% of cases) [THO 18]. In addition, radioactive labeling can be carried out in two ways; this is either by replacing a stable atom in a molecule with one of its radioactive isotopes, or by attaching an additional, radioactive atom to a molecule. The radiotracer is chosen on the basis of its radioactive half-life, which must be sufficiently short for the tracer mass to be very low, but still correspond to a detectable activity. It is also chosen for the nature and energy of the radiation emitted [CEA 18]. Unlike morphological imaging, where the radiation is external to the body, the radiation used in nuclear medicine imaging is internal. The biological support molecule is used to monitor the activity of specific organic functions in living tissues. The isotope added must not alter the biological function of the pharmaceutical molecule, while maintaining a strong bond with it.
- Angela Newing(Author)
- 1999(Publication Date)
- ICP(Publisher)
Chapter 5 NUCLEAR MEDICINE Nuclear medicine covers the medical uses of radioactive isotopes primarily for diagnostic purposes but also, in a few instances, for therapy. For diagnosis, the aim is to be able to make a clinical diagnosis while giving the least practicable radiation dose to the patient. Diagnostic procedures can be divided into four general categories which depend upon either, localisation, dilution, diffusion (or flow), or biochemical and metabolic properties. Diagnostic radiology and nuclear medicine are complementary techniques. In general, diagnostic X-rays show body structure whereas isotope studies show function. Diagnostic nuclear medicine relies upon the use of artificially produced isotopes with short half lives in order that patient dose is minimised, and that repeat investigations are possible. The production of such isotopes, although not the very short lived ones used today, began in 1932 when the British physicists J. D. Cockroft and E. T. S. Walton built a high voltage particle accelerator capable of producing protons with sufficient energy to cause nuclear transformations. In the first Cockroft-Walton experiments, lithium nuclei, containing three protons, were bombarded with protons. Those nuclei which captured a fourth proton from the beam were transformed into beryllium nuclei which themselves split into two helium nuclei (alpha particles). Rutherford's classic experiments at the Cavendish Laboratory, Cambridge, in 1919, had established that alpha particles were capable of transforming one element into another. He used radium alpha particles to convert stable nitrogen into radioactive oxygen-15 which has a half life of two minutes. Shortly after the Cockroft-Walton accelerator was built, E. 0. Lawrence at the University of California in America, developed a circular accelerator called the cyclotron. This used a magnetic field combined with a rapidly oscillating voltage to accelerate nuclear particles along a spiral path, thus 125
eBook - PDF- David Dowsett, Patrick A Kenny, R Eugene Johnston(Authors)
- 2006(Publication Date)
- CRC Press(Publisher)
16 Nuclear medicine: radiopharmaceuticals and imaging equipment Clinical nuclides and radiopharmaceuticals 469 Dosimetry 472 Planar imaging 478 Single photon emission tomography 483 Positron emission tomography 490 Comparison of other tomographic techniques 505 Further reading 506 Keywords 506 16.1 CLINICAL NUCLIDES AND RADIOPHARMACEUTICALS The parallel development of instrumentation and the chemistry of clinically useful isotopes has maintained nuclear medicine as a premier diagnostic imaging service. The distribution of labeled radiopharmaceu-ticals in the body allows imaging of organ function since these chemical substances are actively accumu-lated (e.g. MDP bone agents, liver colloid) or excreted (e.g. DTPA, EHIDA) by the target organ. Although several radionuclides are available for nuclear medicine the predominant one is 99m Tc; it complies with most of the requirements for an ideal clinical isotope. It is produced by a generator, which can be kept in the nuclear medicine radiopharmacy, and renewed at weekly intervals. It is immediately available, thereby allowing a nuclear medicine clinic to offer a continuous service. 16.1.1 99m Tc generator specifications Basic information on generator construction was given earlier in Chapter 15, Section 15.4.4. The tech-netium generator used for routine nuclear medicine purposes is commonly eluted each morning; Fig. 16.1 shows the decreasing activity of available 99m Tc A in equilibrium with 99 Mo and eluted 99m Tc over a 3 day period (curves B and C). Partial elution of the generator gives high activity in a small volume, which is useful for efficient label-ing of small samples (white cells and complex mole-cules). Specific concentration for small volumes is plotted in Fig.
eBook - PDF- Aamir Shahzad, Sajid Bashir, Aamir Shahzad, Sajid Bashir(Authors)
- 2019(Publication Date)
- IntechOpen(Publisher)
It is fundamental to remember that medicinal imaging thinks are performed to influence quiet care. Thus, a medicinal imaging methodology performed at bring down measurement is just “sensible” on the off chance that it answers the clinical inquiry. As such, a lower dosage 86 Nuclear Medicine Physics methodology that is lacking to answer the clinical inquiry conveys radiation dosage to the patient without the imperative advantage and is generally “not sensible.” The procedure of self-appraisal must be bolstered by a high level institutional responsibility regarding quality restorative imaging and the fitting conveyance of radiation measurement to patients expected to help the clinical administration of every patient. The institutional responsibility must incor-porate allotment of the fundamental assets to fulfill these assignments. Fundamental assets incorporate time for staff to commit to the procedure, and time on imaging frameworks to test potential measurement decreases strategies, where required. Budgetary designations may be expected to pay for administrations are not performed by staff or for substitution clinical scope while staff individuals commit time to the self-assessment. 1.6. Nuclear medicine Atomic drug is a branch of medicinal imaging that utilizations radiopharmaceuticals to look at the capacity and structure of organs and tissue capacity and structure. A radiopharmaceutical is the most part comprised of two sections: a pharmaceutical that objective a particular organ or tissue and a radioactive material (radionuclide) that emits little measures of radiation. 1.7. Nuclear medicine procedures Name of NM procedures are HIDA scan, Bone scan, DTPA renal scan, cardiac rest scan, car -diac stress scan, parathyroid scan, thyroid scan, DMSA and GI bleeding, etc. 1.8. Nuclear medicine scans 1.8.1. Bone scan Bone scan is also known as skeleton scan, is an imaging test. To diagnose the problem in bones, it uses very small amount of radioactive material.
- Grant Mair, Andrew Baird, Andrew Nisbet(Authors)
- 2009(Publication Date)
- CRC Press(Publisher)
7. Radionuclide Imaging: Questions 1. Regarding radioactivity: a. All stable nuclei have equal numbers of protons and neutrons b. Isotopes are nuclides of the same element which have differing numbers of neutrons c. Radionuclides are by definition unstable d. Most radioactive substances occur naturally e. The Syste `m International (SI) unit of radioactivity is the becquerel (Bq) 2. Concerning isotopes: a. Radionuclides occur naturally and are present in the body at all times b. They will always have the same position in the periodic table c. The atomic mass number is the same for all isotopes of a given element d. Neutron deficit is defined as a nucleus with fewer neutrons than protons e. 99 Technetium (Tc-99) has a physical half-life of 6 hours 3. Radioactive decay: a. Can occur in nuclides with either a neutron excess or a neutron deficit b. In b 2 decay, the mass of the nuclide is unchanged but the atomic number will have increased c. Isomeric transition means only the energy state of the nuclide changes d. A neutron deficit can be balanced by combining a K-shell electron with a proton to create an extra neutron e. Emitted gamma rays will vary in their energy from different atoms of the same radionuclide 4. In radioactive decay of a nucleus the following result in a decrease in atomic mass number: a. K-shell capture b. Positron emission c. Alpha particle emission d. Beta particle emission e. Isomeric transition 7. Radionuclide Imaging: Questions 71 5. Regarding positrons: a. A positron has an identical charge to a proton b. A positron has an identical mass to a photon c. Positrons are captured by the positron emission tomography (PET) scanner detector array to produce a three-dimensional (3D) map of nucleus decay d. Positrons are an example of b emission e. Positrons are likely to be emitted by a nucleus with a proton deficit 6.
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