Recent advancements in modern x ray tube

All the advancements in X-ray tubes till date are done to increase the Tube heat storage capacity thus increasing the lifetime of x -ray tubes. This slide explains about these recent advancements in x-ray tubes.

1. Recent Advancements in Modern X-ray tube

2. History X-ray tubes evolved from experimental  Crookes tubes  with which X-rays were first discovered on 1895, by the German physicist  Wilhelm Conrad Röntgen . Also callled Cold cathode type X-ray tubes. Electrons formed by ionization of Gas inside the tube. Platinum Anode Used.

3. Coolidge Tube Introduced in 1913 Hot Cathode X-ray tube Works on principle of thermionic Emission. Stationary Anode X-ray Tube Based on model of coolidge tube Tube was modified ie; More Cylinderical with Modified cooling techniques.

4. Modern X-ray Tube Introduced in 1929 Modified Coolidge tube Contains Rotor and Stator Coils with ball bearing system. Rotation 3000 RPM

5. Advancement in Rotating Anode X-ray Tube Dual Focus X-ray tube Two filaments Used Most of diagnostic tubes have two focal spots; Large and small Large is used when large body parts are imagined - high heat Small is used when better spatial resolution is desired – better detail Small Focal track is superimposed over large focal track

6. Advancement in Rotating Anode X-ray Tube New Anode material used Tungsten (90%) – Rhenium (10%) Alloy on Molybednum backed on Graphite for good Heat Storage and dissipation. Lubrication material used in bearings of Rotor-stator coil- Silver powder which allows high rotation Increased speed of Rotation 9000 – 10,000 RPM allows use of high mA and shorter exposure time. Reduced Anode angle ie; 6°

7. Straton Tube Most advanced technology till date. Type of Rotating Envelope Tube (RET) introduced by Siemens Medical Solutions RET-tube implies rotation of the entire tube with respect to the anode axis.

8. Straton Tube Characteristic features Electron beam is shaped and controlled by magnetic field. Cooling surface of anode in direct contact with cooling fluid. A rotating envelope

9. Straton Tube It consist of four systems Tube Envelope system Electron Emission system Magnetic deflection system Cooling system

10. Straton Tube Tube Envelope system Material used – Non Magnetic stainless steel Directly attached to anode disc Annular/Circular Window (Thickness – 0.2 mm) Maximum rotation speed – 9600 RPM

11. Straton Tube Anode Assembly Target Track made up of- 90% Tungsten and 10% Rhenium Anode Disc is made up of- Tungsten, Zirconium, Molybdenum body (TZM Alloy) Boilling Point – 4612 Melting Point - 2600

12. Straton Tube Electron Emission system Cathode Assembly consist of Focusing Cup Flat Emitter Shape of emitter is – circular Material – Tungsten Thickness - 100µm Diameter - 5µm Meander like path – for filament heating

13. Straton Tube Magnetic Deflection System There are three coils present- R – Coil – Deflect the beam Radial direction onto the focal spot Q – Coil – Focus beam to determine Size Phi – Coils – Deflection of flying focal spot intangential direction Microcontroller controls individual coil current. Electronically adjusted focal spot Best Image quality

14. Straton Tube Cooling System Unlike other rotating anode x-ray tube which dissipates heat by radiation, Straton tubes dissipates heat by convection process. Anode Disc comes in direct contact with cooling Oil. Oil rotation is turbine flow Flow of oil - during exposure is 25 ltr/Min - during pump running 8 ltr/Min Oil used – Mineral Oil When apower of 100 KW is applied , the temprature of focal spot reaches 2500°C and temprature on focal track reaches 2000°C. But the back of anode has temprature of 200°C. This difference in temprature is due to direct cooling.

15. Advantages Better Heat Dissipation Various size multiple focal spot Longer tube life Can be used in high KV and high mA technique for prolonged Duration. Ie; High mAs

16. Thank You Santosh ojha [email protected]