PPT VAICON 2025 MARCH 20.pptx during vaicon

varicose veins

1. LASER and RF Basic Physics Dr. Satyendra Kumar Tiwary Professor, Institute of Medical sciences Banaras Hindu University Varanasi 221005 Email:[email protected]

2. ॐ अग्निमीळे पुरोहितं यज्ञस्य देवमृत्विजम् । होतारं रत्नधातमम् ॥१॥ ( ऋग्वेद )(2000 B.C.E.) Om , I  praise Agni  who is the  Purohita  (Priest) of the  Yagya  (Sacrifice) (Priest leading the Sacrifice), (as well as) its  Ritvij  (Priest performing Sacrifice at proper times); the Yagya which is directed towards the  Devas , 1.2:  Who is (also) the  Hotara  (Priest invoking the Gods) and the  bestower  of  Ratna  (Wealth of physical, mental and spiritual plane).

3. What is Laser? Light Amplification by Stimulated Emission of Radiation Lasers are marvels of science, combining physics, optics, and engineering Highly concentrated and coherent light beams Stimulating electronic, ionic, or molecular transitions to higher energy levels Require Higher complex driver circuitry than LEDs Laser action occurs from three main processes: photon absorption, spontaneous emission, and stimulated emission .

4. T he operation of the Laser Light: Coherent, polarized The stimulating and emitted photons have the same: frequency phase direction

5. Properties of Laser Monochromatic Concentrate in a narrow range of wavelengths (one specific colour). Coherent All the emitted photons bear a constant phase relationship with each other in both time and phase Directional A very tight beam which is very strong and concentrated.

6. Basic concepts for a laser Absorption Spontaneous Emission Stimulated Emission Population inversion

7. How a Laser Works

8. Spontaneous emission: Spontaneous emission is the process of emitting light or photons naturally while electrons falling to the lower energy state. In laser diodes, the valence band electrons or valence electrons are in the lower energy state. Therefore, the holes generated after the valence electrons left are also in the lower energy state.  On the other hand, the conduction band electrons or free electrons are in the higher energy state.

9. In simple words, free electrons have more energy than holes. The free electrons in the conduction band need to lose their extra energy in order to recombine with the holes in the valence band. The free electrons in the conduction band will not stay for long period. After a short period, the free electrons recombine with the lower energy holes by releasing energy in the form of photons.

10. Cont…

11. Stimulated emission: Stimulated emission is the process by which excited electrons or free electrons are stimulated to fall into the lower energy state by releasing energy in the form of light. The stimulated emission is an artificial process. In stimulated emission, the excited electrons or free electrons need not wait for the completion of their lifetime. Before the completion of their lifetime, the incident or external photons will force the free electrons to recombine with the holes. In stimulated emission, each incident photon will generate two photons. All the photons generated due to the stimulated emission will travel in the same direction. As a result, a narrow beam of high-intensity laser light is produced.

12. Cont…

13. Diagram

14. Stimulated Emission     A narrow beam of high intensity laser light is produced

15. Population Inversion A state in which a substance has been energized, or excited to specific energy levels. More atoms or molecules are in a higher excited state. The process of producing a population inversion is called pumping . Examples: → by lamps of appropriate intensity →by electrical discharge

16. RFA Radiofrequency Ablation (RFA) for varicose veins is a fascinating application of physics principles

17. Mechanism of Action Radiofrequency energy to generate heat within the vein wall. Achieved through a catheter that emits radiofrequency waves. Resistive heating in the vein wall. Raising temperature approximately 120°C. This heat causes: Collagen denaturation: The structural proteins in the vein wall shrink. Vein closure: The vein collapses and seals shut.

18. Energy Transfer The catheter delivers energy in a controlled manner, ensuring uniform heating along the vein segment. The heat is generated by the resistance of the vein tissue to the radiofrequency current, which is why it's called resistive heating.

19. Thermal Dynamics The heat generated is localized to the vein wall, minimizing damage to surrounding tissues. The temperature is carefully monitored and maintained at 120°C to ensure effective vein closure without excessive thermal spread.

20. Advantages of RFA Physics The controlled and uniform heating reduces the risk of complications like skin burns or nerve damage. The steady temperature profile ensures consistent results, making RFA a reliable treatment option.

21. RFA & EVLT RFA: Uses radiofrequency waves to generate heat, which targets the vein walls. RFA: The heat from radiofrequency waves causes the vein to shrink and collapse. RFA: The heat application is automated and uniform. EVLT: Employs laser energy to heat and seal the vein. EVLT: The laser energy heats the blood inside the vein, causing it to clot and seal. EVLT: The laser application is manually controlled, requiring precision.

22. RFA & EVLT Frequency and Heat Generation: RFA utilizes alternating radiofrequency currents (typically 300–500 kHz Thermal Penetration: Controlled heat transfer is a key advantage of RFA. Energy Delivery: RFA catheters often employ a feedback mechanism (temperature-controlled) to maintain consistent heating, ensuring effective yet safe tissue ablation. Laser Wavelength and Tissue Interaction: EVLT uses laser wavelengths (usually 810–1470 nm) that target hemoglobin and water molecules. 810–980 nm: ( hemoglobin ) 1320–1470 nm: (Water) Heat Generation Mechanism: The laser generates localized heat, leading to endothelial cell damage and vein collapse. Energy Focus: The laser catheter delivers energy in pulses or continuously, with precision controlled by the operator, allowing customization based on vein anatomy.

23. Conclusion: RFA: High frequency electromagnetic waves.(3Hz to 3 GHZ) Laser: Stimulating atoms or molecules to emit light at specific wavelengths(810nm to 1940nm)