85. Theoretical and Technical basis of X-ray diagnostics

yaboiemil's version from 2016-02-07 19:13


1. X-rays are produced by Bremsstrahlung.
2. X-rays are high energy photons.
3. X-ray images are a result of the absorption and attenuation of these high-energy photons as they pass
through the body, which can be expressed by...

Attenuation of X-rays:



Question Answer
I0Original Intensity
IFinal Intensity
dThickness of absorbing layer
micrometer symbolattenuation coefficient
ebase of natural logarithms


4. The attenuation coefficient will depend on the proton number of the absorbing medium, the energy of
the radiation and the interaction of photons with matter (e.g. photoelectric effect, compton scattering,
electron-positron pair production)
5. The x-ray is made up of 4 main parts:

Source of High Voltage

6.Made up of:


Question Answer
The TransformerTransforms normal mains voltage into v. high voltage needed for x-ray production
RectifierTurns AC into DC because X-ray production can only use DC
CircuitUsed to smooth out the pulsating DC from the rectifier
Mains voltage230 - 380V

The X-ray Tube

7. Made up of a hot cathode (filament) and a cold anode (tungsten usually)
8. A beam of electrons is accelerated between the hot cathode onto the focus area of the cold anode.
9. This decelerates the electrons very quickly (brehmsstrahlung) causing excess energy to be converted
into photons.
10. The energy of the electrons incident upon the anode is U.e ...



Question Answer
U.eEnergy of incident electron upon anode
hPlanck's Constant (6.62 x 10^-34 m^2kg/s)
fmaxMaximum frequency
Lamda minMinimum Wavelength

The Control Panel


11. Contains a voltmeter, ammeter
12. Helps to position patient and machinery
13. The control panel is behind a shield to protect the nurse/assistant

The Mechanical Part


14. Stand to hold the tube
15. Examination table
16. Bucky grid under the patient
17. Film/fluorescent screen under the patient
18. Image intensifier


Question Answer
BremsstrahlungElectromagnetic radiation produced from the deceleration of charged particles.