1. PRODUCTION OF X-RAY & X-RAY SPECTRUMBY
Dr Nahla Nagy

2. X-RAY EMETION SPECTRUM

3. History of Radiology November 11, 1895, Wilhelm Conrad Roentgen
Roentgen the first Nobel prize in physics in 1901

4. How They Were Discovered
Röntgen discovered the new ray while
working with a cathode tube in his
laboratory.

5. The tube was a glass bulb that had
positive and negative electrodes inside.
When the air was removed from the
tube, and a high voltage was applied it
produced a florescent glow.

6. Röntgen-Cathode tube

7. To further observe the rays he
positioned a screen in front of the tube.
He began placing various objects
between the screen and the tube that
was emitting the X-rays.

8. He discovered that the rays or “invisible
light” passed right through pieces of
black paper and thin sheets of
aluminum and copper but that the light
did not pass through blocks of lead and
his bones, and instead these objects
casted shadows on the screen.

9. Roentgen’s Wife’s Hand
X-ray of a colleagues hand after presenting the“new ray” to the Physics – Medical Association
1st X-ray?
Roentgen’s Wife’s Hand

10. X-Ray-Tube The main parts of the x-ray tube are Cathode/filament
Typical electron current is A for short exposures (< 100 ms)
Anode/target
Glass/metal envelope
Accelerating voltage
Typical voltage is kVp

11. X-Ray-Tube

12. X-RAY PRODUCTION X-rays are produced when electrons are
accelerated and collide with a target
Bremsstrahlung x-rays
Characteristic x-rays

13. X-rays are sometimes characterized by the generating voltage
kV soft x-rays
kV diagnostic x-rays
kV orthovoltage x-rays
300 kV – 1 MV intermediate energy x-rays
> 1MV megavoltage x-rays

14. BREMSSTRAHLUNG Bremsstrahlung:(braking) x-rays are produced
when incident electrons interact with nuclear
electric fields, which slow them down (brake)
and change their direction.

15. BREMSSTRAHLUNG

16. Bremsstrahlung x-rays produce a continuous spectrum of radiation, up to a maximum energy determined by the maximum kinetic energy of the incident electron.
The closer the electron passes to the nucleus, the greater the interaction of the incident electron with the nucleus, and the higher the energy of the resulting x-ray.

17. The energy of the x-rays varies from
zero to the maximum kinetic energy of
the electron (x-ray tube kVp).
The probability of bremsstrahlung goes
as Z2, hence high Z targets are more
effective than low Z

18. Maximum photon energies correspond to minimum x-ray wavelengths.
-The majority of x-rays produced in x-ray tubes are via the bremsstrahlung process.
-Bremsstrahlung x-ray production increases with the accelerating voltage (kV) and the atomic number (Z) of the anode.

19. BREMS. EMISSION-CONTINUOUS

20. Characteristic radiation
Characteristic radiation is the result of ionization and is produced when inner-shell electrons of the anode target are ejected by the incident electrons.
-To eject a bound atomic electron, the incident electron must have energy greater than the binding energy.

21. CHARACTERISTIC X-RAY

22. The resultant vacancy is filled by an
outer-shell electron, and the energy
difference is emitted as characteristic
radiation (e.g., K-shell x-rays, L-shell x-
rays), as shown in Fig.

24. Characteristic x-rays occur only at discrete energy levels, unlike the continuous energy spectrum of bremsstrahlung.
-Each anode material emits characteristic x-rays of a given energy, as listed in Table 2.1.

26. K-shell characteristic x-ray energies are always slightly lower than the K-shell binding energy. (Table 1.4 lists K-shell binding energies).
-K-shell electrons are ejected only if incident electrons have energies greater than the K-shell binding energy.
-For tungsten, K-shell characteristic x-rays are only produced when the applied voltage exceeds 69.5 kV (K-shell binding energy is 69.5 keV).

28. For molybdenum, K-shell characteristic x-rays are only produced when the applied voltage exceeds 20 kV.
-L-shell radiation also accompanies K-shell radiation, but because L-shell characteristic x-rays have very low energies, they are absorbed by the glass of the x-ray tube.
-Only K-shell characteristic x-rays are important in diagnostic radiology.

29. CHARACTERISTIC EMISSION- LESS POLYENERGETIC

30. X-RAY EMISSION SPECTRUM
BREMS
INTENSITY
X-RAY ENERGY

31. X-RAY EMISSION SPECTRUM
L-CHARACTERISTIC
K-CHARACTERISTIC
BREMS
INTENSITY
X-RAY ENERGY

32. X-RAY EMISSION SPECTRUM
CHARACTERISTIC
BREMS

33. MAXIMUM ENERGY OF AN X-RAY IN THE BEAM
= kVp OF OPERATION
kVpeak

34. GREATEST # OF PHOTONS IS EMITTED WITH ENERGY:
APPROX. 1/3 OF MAX
PHOTON ENERGY

35. THANK YOU