Скачать презентацию X-Rays Radiation Application in Medicine IONIZING RADIATION
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X-Rays Radiation Application in Medicine
IONIZING RADIATION ELECTROMAGNETIC WAVES WITH WAVELENGTH < nм 10 (depends on natureroentgen &γ: rays ) CORPUSCULAR RADIATION α-particles flow Proton radiation β-particles flow Neutron radiation Space rays Electromagnetic waves’ scale Ionizing radiat іоn
HYSTORY OF X-RAYS DISCOVERY ROENTGEN RADIATION is electromagnetic waves with wavelength < 10 нм. Е>10 е. V. W. Roentgen – is an author of fundamental works in different fields of experimental physics. 1895 he discovered new kind of rays & called them XRays. These rays are known now as Roentgen Rays. He made the first roentgen pictures – pictures of his & his wife’s arms. Wilhelm Roentgen (1845 -1923), germany physicist – experimentalist, Nobel prize laureate (1901)
COMPARE THE FIRST ROENTGEN PICTURE & THE MODERN ONE First roentgen picture of W. Roentgen’s wife’s arm Modern roentgen picture of an arm
ROENTGEN TUBE CONSTRUCTION
ROENTGEN RADIATION Braking (Bremsstrahlung) Ф characteristic Braking (Bremsstrahlung) radiation 3 U 1
CHARACTERISTIC RADIATION When a sample is bombarded by an electron beam, some electrons are knocked out of their shells in a process called inner-shell ionization. About 0. 1% of the electrons produce K-shell vacancies; most produce heat. Outer-shell electrons fall in to fill a vacancy in a process of selfneutralization. The energy required to produce inner-shell ionization is termed the excitation potential or critical ionization potential (E c). MOZLY LAW А, В=const Z – element number ,
Roentgen radiation interaction with matter COHERENT LENGTHS PHOTOEFFECT hν INCOHERENT DISPERSION (COMPTON EFFECT) COHERENT DISPERSION hν hν < Aи The direction of electro magnetic radiation is change. Used for roentgen structure analysis.
COHERENT LENGTHS USE Due to the phenomena of diffraction and interference of X-rays on a crystal on a photographic plate, behind the crystal, symmetrical pattern of spots (Lauegram) appears. German scientist Max von Laue (1879 -1960) was the first who predicted the possibility of using X-rays to determine the structure of bodies. Lauehram reading when the structure of crystal is unknown - a difficult task. If the structure of the crystal is known, the Laue method allows to determine the Lauehram wavelengths, to make Roentgen spectroscopy. For this purpose it is better to use the method developed by father and son Braggs. Each crystal can be imagined as a set of separate parallel layers of ions or atoms, called the crystal planes. Let the distance between the two crystalplane we marked by d. Two parallel on-me 1 and 2 are falling at an angle α to theseplanes and diffracts at ions A and B. diffracted rays 1 'and 2'interfere, and if the beam 2. 2 'has relatively beam 1. 1' path difference equal to l or a whole multiple of it, their intensity yutsyacomplexity. Spot on a photographic plate occurs only when strictlya corner, which is performed for conditions of
X-RAYS IMAGING SHADOW PROECTIONS
X-RAYS DIAGNOSTICS
COMPUTER TOMOGRAPHY
COMPUTER TOMOGRAPHY
SPIRAL TOMOGRAPHY
MAMMOGRAPHY
X-RAYS IN STOMOTOLOGY
X-RAYS DOSIMETRY