Page 1 of 2: Radiology--lasers

drkbravva · Credits: 24026 My Scrapbook My Reading List 1 Books

Q-depth of tissue affectd by which laser is the maximum among the following
1-Co2
2-Argon
3-Nd-Yag
4-KTP.

got confused on this one.....pls......guide me to the correct ans.....

docvin · Credits: 1662 My Scrapbook

is it ND Yag??
what do u think it is....

decembermist · Credits: 41121 My Scrapbook

The depth of penetration of laser light depends on the light`s wavelength, on whether the laser is superpulsed, and on the power output , but also on the technical design of the apparatus and the treatment technique used

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Wats the ans given - I too go for 3)

drkbravva · Credits: 24026 My Scrapbook My Reading List 1 Books

THANKS MIST...

LASER=Light Amplification by the Stimulated Emission of Radiation.

Nd:YAG Laser: A true workhorse, the Nd:YAG emits a near-infrared invisible light at 1064nm or 1320nm. It may be delivered in CW or "long pulsed" (millisecond domain) mode through a fiber to a sapphire tip to cut tissue, or because of its deep penetration, used to directly coagulate tissue. The Q-Switched Nd:YAG is effective for black tattoo ink , and has been used with fair results for hair removal. Millisecond-range Nd:YAG laser light is very effective for long-term hair removal.

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drkbravva · Credits: 24026 My Scrapbook My Reading List 1 Books

Deeper vessels/tissues require a longer wavelength to allow penetration to their depth.

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ardy · Credits: 12764 My Scrapbook

if we go by wavelength then co2=106OOnm>NdYAG=1060nm

manpreet108 · Credits: 30682 My Scrapbook

if i rem the physics part correctly --[did so long back--i am sorry if thats a wron g formula]==

energy of wave==h[nu]=hc/lambda

so energy is inversely proportional to lambda[wavelenghth.

that means shorter the wavelength greater the energy hence penetration..

and as ardy is saying-ndyag has shorter wavelength..so that cd be ans here..
what is ans given btw??

i dont understand the line quoted from emed-- i think thats not correct

King75 · Credits: 3084 My Scrapbook

Hello, guys
Manu, what u have recalled about the energy equation is right. And What DrKbravva had quoted from emedicine is right too.

After u read the following bits i have selected after a thorough research on the matter, i hope it solves the confusion.

Carbon dioxide (CO2) laser -- This type of laser can remove thin layers from the skin's surface without penetrating the deeper layers. This technique is particularly useful in treating tumors that have not spread deep into the skin and certain precancerous conditions. As an alternative to traditional scalpel surgery, the CO2 laser is also able to cut the skin. The laser is used in this way to remove skin cancers.

Neodymium:yttrium-aluminum-garnet (Nd:YAG) laser -- Light from this laser can penetrate deeper into tissue than light from the other types of lasers, and it can cause blood to clot quickly. It can be carried through optical fibers to less accessible parts of the body. This type of laser is sometimes used to treat throat cancers.

Argon laser -- This laser can pass through only superficial layers of tissue and is therefore useful in Dermatology and in eye surgery. It also is used with light-sensitive dyes to treat tumors in a procedure known as photodynamic therapy (PDT).

LASER TYPE
WAVELENGTH (Nanometers)

Argon Fluoride
193

Argon
457 - 528 (514.5 and 488 most used)

Frequency doubled Nd:YAG
532

Nd:YAG
1064

Carbon Dioxide
10600

Q: How deep into tissue can a laser penetrate?

A: The depth of penetration of laser light depends on many parameters such as the laser's wavelength, the power, the type of device driver (pulse or continuous wave mode), and lastly the technique used. The higher the wavelength typically the deeper the penetration; however, with wavelengths greater than 930nm the water in the tissue absorbs light and the depth of penetration is drastically reduced. Secondly, devices of greater power can provide better penetration. Thirdly, the peak power of the unit is the most critical factor in providing depth of penetration. Thus, devices which are true pulsed systems have better penetration versus continuous wave devices because they have greater peak powers. Lastly, the technique of scanning provides for less penetration compared to the in contact method.

CO2 is the most commonly used laser for laryngeal laser surgery (e.g., laryngeal condylomata, papilloma’s and tumors). The long wave length of CO2 (10.6 um) results in it’s total absorption in the first few cell layers providing accurate vaporization with minimal peripheral injury. It offers the best precision (0.2mm) of any of the lasers used, unfortunately it cannot be used through a fiberoptic scope. Errant beams of CO2, which can result in corneal damage, can be stopped with any clear lens material.

Neodymium-yttrium aluminum garnet (Nd-YAG) lasers are invisible, and are used for coagulation of hemorrhagic lesions such as necrotic respiratory tumors and GI varices. In contrast to CO2, Nd-YAG lasers with a wave length of 1.06 um, penetrate tissues causing deep damage with more thermocoagulation and less vaporization. Nd-YAG lasers can be used through a fiberoptic scope, however penetration is variable with a greater potential for damage to normal tissue compared to CO2 lasers.

Ref

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Thanku guys . I hope i haven't worsened the situation.

Good discussion. Keep it up.

King75 · Credits: 3084 My Scrapbook

So The answer is ND:YAG Laser

Thank u

drkbravva · Credits: 24026 My Scrapbook My Reading List 1 Books

ya given was answer is ND:YAG Laser

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