Ionizing radiation is flows of particles and electromagnetic quanta, whose interaction with a medium leads to ionizing of its atoms and molecules. Ionizing radiations are X-ray and г-radiation, flows of б-particles, electrons, positrons, protons, neutrons. This section describes both ionizing radiation sources (X-ray tubes, radionuclides1, particle accelerators) and physical aspects of applying this radiation for medical purposes. Physicians and biologists are undoubtedly interested in such problems as interaction of ionizing radiation with materials and elements of ionizing radiation dosimetry.
Chapter 31
X-ray (roentgen) radiation
X-radiation is electromagnetic waves with a wavelength of approximately from 80 to 10-5 nm. X-radiation with the longest wavelength is overlapped by short-wave ultraviolet radiation, the short wavelength X-radiation is overlapped by long wavelength г-radiation. According to the method of excitation, X-radiation is subdivided into continuous and characteristic.
§ 31.1. X-RAY TUBE STRUCTURE. BREMSSTRAHLUNG X-RAYS
The most common source of X-ray is an X-ray tube, which is a two-electrode vacuum device (fig. 31.1). Heating cathode 1 emits electrons 4. Anode 2, often called anti-cathode, has an inclined surface in order to direct resulting X-ray radiation 3 at an angle to the horizontal axis of the tube. The anode is made from a good conductive material to remove the heat generated by electron impact. The anode surface is made from refractory materials with a large atomic number in the Mendeleev? periodic table, for example, tungsten. In certain cases, the anode is intentionally cooled with water or oil.