What Student Need to Know about Radionuclide imaging in Radio Diagnosis скачать в хорошем качестве

What Student Need to Know about Radionuclide imaging in Radio Diagnosis

The discipline of nuclear medicine consists of radionuclide imaging and radionuclide therapy with the number of patients having radionuclide imaging studies being much greater than those who have radionuclide therapy. The use of radionuclide imaging and therapeutic procedures is increasing because they have an important role in the management of patients with cancer. Radionuclide imaging is the most often performed procedure in molecular imaging. Nuclear medicine has been performing molecular imaging since the first radionuclide studies that were performed with 131I sodium iodide for diagnosing and treating thyroid cancer. Images obtained with a moving detector are called scans, whereas images obtained with a stationary camera device are called scintiphotographs. To perform radionuclide imaging, a radioactive material (radiopharmaceutical) is administered and the radiation emitted by the radiopharmaceutical detected by sensitive radiation detectors located outside of the patient being studied. Radiopharmaceuticals that provide more sensitive and specific detection of cancers are being developed, and the methods of detecting the radiation are improving. The dose of radiation that your body receives is very small. In many cases, the level of radiation involved is not much different to a series of a few normal X-rays. A radionuclide is a radioactive form of an element, which means it is an unstable atom that becomes more stable by releasing energy as radiation. Most radionuclides release high-energy photons as gamma rays (which are x-rays that occur in nature, that are not man-made) or particles (such as positrons, which are used in positron emission tomography). Radionuclide imaging is commonly separated into single-photon imaging and positron imaging. The devices used for imaging the single-photon-emitting radionuclides are different than those for imaging positron-emitting radionuclides. Single-photon radionuclides emit gamma rays in the energy range of approximately 75 to 360 KeV. These radionuclides include 99mTc, 131I, 201Tl, 111In, 67Ga. Devices known as gamma cameras detect these radionuclides, and these devices can perform regional imaging, whole-body imaging, and single-photon emission computed tomography (SPECT) imaging. A major advance that is occurring in radionuclide imaging is the combination of gamma camera and computed tomography (CT) scanners and the combination of PET and CT scanners. The radionuclide images provide excellent information concerning the biology of a process but very little, if any, anatomic information. Radioactive tracers have made an immense contribution to the understanding of human physiology and pathology. At the start of the 21st century nuclear imaging has emerged as the main metabolic imaging modality which is of growing importance in drug development and clinical pharmacology. Risks and complications of radionuclide scans Overall radionuclide scans are considered a fairly safe procedure. They are non-invasive and cause little patient discomfort. However, like x-ray and other investigations they expose the body to a small dose of radiation. This can damage cells and cause mutations particularly in growing fetuses. Therefore if you are pregnant you must be made aware of the potential risks to your baby. In addition there is also a small risk that you may be allergic to the chemicals used for the scan. In patients sensitive to the chemicals nausea, vomiting and headaches can occur. Labeling with a radionuclide For scanning, a radionuclide is used to label a substance that accumulates in a specific part of the body. Different substances are used depending on which part of the body is to be evaluated. A substance may accumulate because the body uses (metabolizes) it, as for the following: • Iodine is used to make thyroid hormones and thus accumulates in the thyroid gland. • Diphosphonate accumulates where bone is repairing or rebuilding itself. Or a substance may abnormally accumulate in a specific area, as for the following: • Red blood cells accumulate in the intestine when the intestine is bleeding rapidly. • White blood cells accumulate in areas that are inflamed or infected. Before, during, and after the procedure • Before some tests (such as a gallbladder scan), the person is asked to refrain from eating and drinking for several hours. Clothing does not usually need to be removed. • The person must lie still during the scanning, which usually takes about 15 minutes. However, sometimes a scan needs to be repeated after a time, often hours later. • After the test, drinking extra fluids to help the body eliminate the radionuclide is recommended. Normal activities can be resumed immediately. • A radionuclide in the body can sometimes set off radioactivity detectors that are used for security purposes. Detectors may be carried by police or be in place around transportation centers and in other high-security areas.