X-RAY RADIATION Constants Units of Energy h = 6.626 - 10-3“ J•sec Planck constant e = 1.6- 10-19 C charge of electron c = 3. 10" m/sec speed of light m = 9.11- 10" kg mass of electron 1 ev = 1,602-10-"J 1 kev = 1,602-10-"J 1. Relationship between X-ray frequency and wavelength: K-cathode A- anode here à is wavelength (m), f is frequency (Hz), c is speed of light (m/sec). electrons -X-rays 2. Energy of X-rays photon: E = hfmar = Amin is minimum wavelength of X-ray radiation (m), fmax is maximum frequency of X-ray radiation (Hz), h is Planck constant (I sec), c is speed of light propagation in vacuum (m'sec). 3. In the X-ray tube, firstly, the energy of electric field is transformed into the kinetic energy of electron motion: mv? ela = and then the kinetic energy of electron motion is transferred into energy of X-ray photons: = hfmax fmax is maximum frequency of X-ray radiation (Hz), h is Planck constant (J'sec), c is speed of light propagation in vacuum (m/sec), e is charge of electron (C), m mass of electron (kg), U, is potential difference or voltage between cathode and anode (V), v is speed of electrons motion (msec). 4. Relationship between wavelenth of X-ray radiation and Voltage on the tube: 121 Amin (um) = U, is potential difference or voltage between cathode and anode (V), Amin is minimum wavelength of X-ray radiation (m). 5. Linear attenuation coefficient (1/m): H= k-p-2.z', k = 10-° is coefficient of proportionality (W/VA), p is density of the material (kg/m'), Z is atomic number of the material, i is wavelength of X-ray radiation (m). 6. Mass attenuation coefficient (m/kg): H == ka'za u is lincar attenuation coefficient, k= 10-" is cocfficient of proportionality (W/VA), p is density of the material (kg/m'), Z is atomic number of the material, i is wavelength of X-ray radiation (m). 7. Attenuation of X-ray radiation intensity: I = lge "Hd here I, is the initial intensity of X-rays (W/m); / is the intensity of X-rays after passing a material of thickness d (W/m²), d is thickness of the adsorbing layer (m), u is linear attenuation coefficient (1/m). 8. Half value layer: In(2) 0,693 HVL = u is linear attenuation coefficient (1/m).