Nuclear Medicine

FusionBodyNuclear medicine is a specialized field of medicine covering all aspects of the use of radioactive substances that are either injected in or ingested by humans with the aim to diagnose or treat a disease. Imaging of tissues or organs can be obtained through the particular properties of radioactivity that produces highly energetic light (such as gamma rays). Radioactive substances concentrate in specific cells and tissues as a consequence of the grafting of radioactive atoms (radionuclides) to drugs that have the property to recognize and therefore stay in these specific cells. In general cells undertaking transformation, growing or dying, such as tumor cells or ischemic tissues in heart, can easily be differentiated from normal neighboring cells, as their biology is altered. Special cameras able to detect the radiations that are emitted from these zones where the drug is concentrated provide nice images of this area. The physician can therefore easily evaluate the extension of the affected area, recognize the disease and provide a diagnostic.

As very small, infinitesimal quantities of radionuclides are used, there are no sideSPECT CT effects due to the radio-activity, which also has a very short life. Depending on the type of radiation, detection equipment must be adapted. Thus, SPECT (Single Photon Emission Computed Tomography) or PET (Positron Emission Tomography) will be used depending if respectively gamma or positron emitting radionuclides will be used. Imaging methods in nuclear medicine are ideal tools for evaluating the extension of a heart infarction, identifying and localizing tumours and metastases or estimating the degree of development of neurodegenerative diseases. They are now also use to follow the efficacy of a therapy. Due to its sensitivity, nuclear medicine detects very faint sources of radioactivity and is therefore ideal for early detection of very small lesions. Another form of radioactivity is expressed by the emission of particles instead of gamma rays. These alpha or beta minus radiations destroy cells by ionization and can therefore be used to kill unwanted cells, if based on the same principle as imaging agents, the radionuclides are linked to vectors that bring them specifically to these areas. This simplified description of the process is the basis of vectorised or metabolic radiotherapy, in other words of nuclear medicine for therapy. This efficient therapeutic technology is mainly used to cure cancer patients, but shows also some applications in rheumatology. The used of beam radiations from external source is called external radiotherapy, and is not part of nuclear medicine, while the use of X-rays, another form of energetic radiation, belongs to the domain of the radiologist.