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How do i calculate specific absorption rate for 1gram or 10 gram tissue in COMSOL?

Posted May 29, 2019, 5:02 a.m. EDT RF & Microwave Engineering Version 5.4 3 Replies

Deepshikha Bhargava
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Hello everyone,

Can anyone tell me how should i differentiate between 1gram and 10 gram specific absorption rate calculation. Unlike comsol, CST has inbuilt option where we can calculate the SAR for specific quantity of a tissue. I am using EM wave frequency domain physics, and want to calculate SAR in a tissue. I am using this formula to calculate it "emw.Qrh/density of tissue", i.e. EM energy absobed by the tissue divided by the density of that tissue. This gives local SAR which cannot be compared with the published literature. Can anyone please tell me how to calculate it for 1gram or 10 gram tissue?

Thankyou.

3 Replies Last Post May 30, 2019, 4:55 a.m. EDT
Edgar J. Kaiser Certified Consultant
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Posted: 5 years ago May 29, 2019, 7:04 a.m. EDT

Hi,

emw.Qrh/rho gives you W/kg. Divide by 1000 and you have W/g.

Cheers Edgar

-------------------
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Hi, emw.Qrh/rho gives you W/kg. Divide by 1000 and you have W/g. Cheers Edgar
Deepshikha Bhargava
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Posted: 5 years ago May 29, 2019, 10:45 p.m. EDT

Thankyou for your reply sir,

But it is not only about changing the units of the SAR.

I want to choose 1gram of the tissue out of all and calculate the SAR for it. So, for example, in that case, SAR will be 2 (W/kg) for 1gram or 2 (W/kg) for 10gram of the tissue.

I can see where the electric field absorption is higher, mostly near to the radiated source. So, i was wondering if i could choose a cube of 1gram at the outer side of the whole object near the radiated source and then can evaluate SAR for that 1 gram tissue only.

International guidelines like ICNIRP/ IEEE have published the SAR exposure limit for these specific quantities of tissues only (Please see attached image). That's why in order to compare the results with these guidelines i have to have SAR for 1 gram and 10 gram tissues only, not a local SAR which comsol gives.

Thankyou for your reply sir, But it is not only about changing the units of the SAR. I want to choose 1gram of the tissue out of all and calculate the SAR for it. So, for example, in that case, SAR will be 2 (W/kg) for 1gram or 2 (W/kg) for 10gram of the tissue. I can see where the electric field absorption is higher, mostly near to the radiated source. So, i was wondering if i could choose a cube of 1gram at the outer side of the whole object near the radiated source and then can evaluate SAR for that 1 gram tissue only. International guidelines like ICNIRP/ IEEE have published the SAR exposure limit for these specific quantities of tissues only (Please see attached image). That's why in order to compare the results with these guidelines i have to have SAR for 1 gram and 10 gram tissues only, not a local SAR which comsol gives.
Edgar J. Kaiser Certified Consultant
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Posted: 5 years ago May 30, 2019, 4:55 a.m. EDT

Then you can do an integration across the volume of interest. Integrating the power density will provide the absorbed power and integrating the gravimetric density provides the mass. You can do that by creating this domain (cube) in the geometry or setup an integration with boolean expressions defining the cube in post processing. There may be others ways as well.

Cheers Edgar

-------------------
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Then you can do an integration across the volume of interest. Integrating the power density will provide the absorbed power and integrating the gravimetric density provides the mass. You can do that by creating this domain (cube) in the geometry or setup an integration with boolean expressions defining the cube in post processing. There may be others ways as well. Cheers Edgar

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