Nuclear medicine

Nuclear medicine involves the use of radioactive substances and nuclear- physical methods in medicine for functional and diagnostic localization and open radionuclides in therapy and radiation protection with its physical, biological and medical foundations.

" In - vivo " method

In vivo methods are measuring methods in which a radiopharmaceutical ( " tracer " ) is introduced into the body, the gamma rays or annihilation radiation from outside the body can be measured very accurately. (Additional information on organ functions return some cases also radioactivity measurements of blood or secretions. )

A radiopharmaceutical is a radionuclide, or the chemical compound of a radionuclide with other substances. As a radiopharmaceutical used in nuclear medicine, essentially depends on two properties:

• Radioactivity ( disintegration behavior and resulting radiation)
• Pharmacokinetics ( distribution in the body, participation in bodily functions, elimination).

Diagnostics

The imaging scintigraphy, positron emission tomography (PET) and SPECT ( single photon emission computed tomography ) form after the tracer principle mainly the function of an organ or organ system from, in contrast to the morphological imaging methods, which mainly show the structure. For example, one used in the bone scan, a radiopharmaceutical ( technetium-99m methylene diphosphonate ), the preference of bone-forming cells ( osteoblasts) is recorded. Normal bone scintigram shows the resulting low activity resulting from physiological remodeling processes. Zones of increased activity can be attributed to increased bone remodeling, however, and so close to pathological processes that occur at the appropriate points in the skeleton. It may be contusions, healing fractures, cancer, benign bone tumors, arthritis or bone inflammation.

Dynamic tests are another example of the functional character of nuclear medicine. For example in the Nierenfunktionsszintigrafie a series of images at intervals between one and 60 seconds is recorded over a period of 20 to 40 minutes. This allows the accumulation and excretion of the radiopharmaceutical in various organs record as curves. This allows for example to assess the performance of a kidney excretion relative to the other.

Also for the field of nuclear medicine include detection and medical assessment of radioactivity that has come with radiation accidents in the body or the natural potassium - 40, which is proportional to the muscle mass. But are non- imaging measurement methods ( scintillation detector, semiconductor detector whole body counter and excretion measurements ) are available.

The most common nuclear medicine procedures are the thyroid scintigraphy, bone scintigraphy, myocardial scintigraphy, and Nierenfunktionsszintigrafie Lungenszintigrafie and positron emission tomography. For many other physiological processes exist nuclear medicine examinations.

As independent from ionizing radiation test methods that exploit the effects of nuclear physics, in order to produce images of the interior of the body and to analyze the composition of tissues, and magnetic resonance spectroscopy are magnetic resonance imaging ( also known as magnetic resonance imaging ) are available. Their statement options are not as pronounced on a functional area such as the classical nuclear medicine, but more on anatomical, where mainly the hydrogen content of tissues extra, just functional, are outcrops. This method is applied by authorized radiologists and nuclear medicine physicians less often.

Since nuclear medicine examinations often lead to anatomically ambiguous findings ( ie, the examiner may look a deviation from the norm, but they can not exactly a special body structure, such as a lymph node group, assign ) are more and more combination units since about 2000 available and installed, in which a nuclear medicine gamma camera or PET scanner is combined with a mechanically fixed to computed tomography. It can be fused into a set of images both functional as well as anatomical data are collected and in a hallway without rearrangement. This improves the clarity and in several critical cases, the accuracy of diagnosis. Such devices are called SPECT - CT or PET-CT; of fully integrated solutions are working, also there are now (2012 ) first - still predominantly used in research - PET - MRI equipment. The clinical value of PET - MRI is not yet be assessed.

Therapy

In nuclear medicine therapy radiopharmaceuticals are used that emit beta or alpha radiation rare. These types of radiation are characterized by a low penetration depth ( a few millimeters in beta radiation, a few microns in alpha radiation ) from. Thus they make an impact at the site of accumulation in the organism. The kinetics of the radiopharmaceutical determines where this enrichment takes place. Thus, the purpose, for example, the radioiodine on the thyroid gland. The radiopharmaceutical is preferentially taken up by hormone-producing follicular cells and destroys local excess or malignant tissue (see also hyperthyroidism, thyroid cancer ). Radioiodine is usually administered orally in the form of a capsule therapy.

A further possibility consists in the administration of man-made, provided with a suitable radionuclide of monoclonal antibodies or peptides (small protein molecules ). Such a radiopharmaceutical may be injected intravenously, will "automatically " be the target organ.

If the target organ spatially well defined and accessible, there is the direct introduction of the therapeutic radionuclide to ( Endoradiotherapie ). One such method is the synovectomy, which is increasingly performed in chronic polyarthritis, activated osteoarthritis or other joint diseases. Here yttrium -90 or another beta emitter is injected into the joint space to obliterate the synovium.

" In vitro " method

As an in- vitro method to laboratory techniques such as radioimmunoassay ( RIA), respectively. In this method, the substance concentration in tissue obtained from the body sample material can be determined by immunological reactions particularly accurate since one reactant has been previously radiolabeled.

The Specialist in Nuclear Medicine

In order for a completed medical studies in Germany to act as a specialist in nuclear medicine, it requires a five -year course,

• Which one year in inpatient patient care, what 6 months can be spent in a different area

The training rules stipulate certain minimum numbers of investigations and therapies. Prior to the certification examination must also be completed even special courses in radiation protection.