# RE:RE: RE: [fluka-discuss]: How to calculate LET(linear energy transfer) with voxel-by-voxel basis

From: Kyung-Nam Lee <leeronaldo_at_naver.com>
Date: Wed, 3 Sep 2014 13:33:10 +0900

Dear, Dr. Vittorio Boccone.

However, I think there is some mis-cummunication between us.

So, I would like to introduce some background and the reason why I have to do this work.

Most of all, my final goal through using fluka is calculation of Dose averaged LET at each voxel.

The reason why I have to know the quantity is for expecting biological effects like a RBE(relative biological effect).

I mean the quantity can be used for expecting or calculation of very important values in "Radiation Therapy" academic field, especially, heavy ion therapy field.

And, because we want to know expected biological effect at various position in the human body, we need to calculate the Dose averaged LET at each voxel.

These are the reason why we need to have Dose averaged LET and calculate at each voxel.

Although we would like to calculate Dose averaged LET at each voxel, given fluka scoring commands cannot give this quantity.

So, we try to use user routine as an alternative way for that work.

I hope these words can help us to clarify interesting points.

1.[This external function is really deprecated and it's not used since very long time. This mean that trying to use it might give you other problems. This is why it is not given anymore with the code.]

==> OK!. I understand what you mean.^^

2. [I really don't see the point on why you want to do it manually. Voxel structure is only used for collecting up the scoring and defining the "regions" of where the material is. The steps on which the interactions and the scoring values are calculate are much smaller than the Voxel segmentation. I suggest you to read the introductory part of the manual to start to understand how FLUKA works. In addition you can profit from the pdf of the FLUKA schools if you go on the course page.]

==> As I mentioned, my final goal is calc. of Dose averaged LET. Calc. of particle LET is first step for calc. of Dose averaged LET. This is because Dose averaged LET can be defined by using LET like this formula(LET_d: Dose Averaged LET, LET: particle LET, D: absorbed dose by ith particle, D_total: Total dose at voxel).

This is why we have to use user routine and do it manually.

3. [I strongly discourage you to use this old routine. It's not even good for education purposes.

There are other routines where you can practice the usage of the COMMON variables, look at the advanced course lectures, there's also an exercise (with solution) that might help you on the way.]

==> Ok. I can see what you point out. I will look at materials for advanced course lectures. Thank you.^^

4. [If you want to build a custom LET map I'm afraid you need to do it by hand

http://www.fluka.org/web_archive/earchive/new-fluka-discuss/4807.html]

==> As you know, "SCORE" command cannot give Dose averaged LET.^^

Have a nice day!!~~^^

Best Regards,

Kyung-Nam Lee

======================================================================

Kyung-Nam Lee, M.S.

Research Physicist

Medical Physics Research Team

Division of Heavy Ion Clinical Researches

Korea Heavy Ion Medical Accelerator Project (KHIMA Project)

KOREA INSTITUTE of RADIOLOGICAL & MEDICAL SCIENCES (KIRAMS)

#215-4 Gongneung-dong Nowon-gu

Seoul 139-709, Korea

Tel: 82-2-970-1737

Fax: 82-2-970-1962

Mobile:82-10-6366-9161

E-Mail: leeronaldo_at_naver.com (with big file), leeronaldo_at_kirams.re.kr

======================================================================

From: Vittorio Boccone [mailto:dr.vittorio.boccone_at_ieee.org]

Sent: Wednesday, September 03, 2014 7:40 AM

To: Kyung-Nam Lee

Subject: Re: RE: [fluka-discuss]: How to calculate LET(linear energy transfer) with voxel-by-voxel basis

Dear Kyung-Nam Lee,

On Tue, Sep 2, 2014 at 4:35 AM, Kyung-Nam Lee <leeronaldo_at_naver.com> wrote:

At the second question, The reason why I would like to have the deq99c.f file is not for calculation of effective dose.

What I really want to know through deq99c.f file is proper usage of "COMMOM variables" about calc. of particle LET and its usage for equivalent dose or effective dose.

This external function is really deprecated and it's not used since very long time. This mean that trying to use it might give you other problems. This is why it is not given anymore with the code.

I mean, for calc. of equivalent dose, as you know, we need to have radiation weighting factor.

This weighting factor can vary for heavy ions due to varied LETs at each voxel(3-D bin with Cartesian coordinate).

Therefore, I think the user routine file is more likely to include the whole process from calc. of particle LET to loading or calc. of the weighting factor at each voxel.

I really don't see the point on why you want to do it manually. Voxel structure is only used for collecting up the scoring and defining the "regions" of where the material is. The steps on which the interactions and the scoring values are calculate are much smaller than the Voxel segmentation. I suggest you to read the introductory part of the manual to start to understand how FLUKA works.

In addition you can profit from the pdf of the FLUKA schools if you go on the course page.

So, if I can learn this process with useful "COMMOM variables"(e.g. JTRACK, XTRACK, YTRACK, ZTRACK, MTRACK. et al.), it will be great help and practice for me to apply to the other case.

So, although scoring with user routine is rather risky way, is there good way for download this file ?

I strongly discourage you to use this old routine. It's not even good for education purposes.

There are other routines where you can practice the usage of the COMMON variables, look at the advanced course lectures, there's also an exercise (with solution) that might help you on the way.

At your comment for scoring LET by using USRYIELD,

As you know, USRYIELD can give many boundary crossing quantity like USRBDX command. But, I would like to scoring LET at each voxel.

So, I think USRYIELD is not more likely to be used for this purpose. I think this work can be performed by using USRBIN command and user routine(comscw.f or fluscw.f).

Is it correct ?

If you want to build a custom LET map I'm afraid you need to do it by hand

http://www.fluka.org/web_archive/earchive/new-fluka-discuss/4807.html

Have a nice day!!~~^^

Best Regards,

Kyung-Nam Lee

======================================================================

Kyung-Nam Lee, M.S.

Research Physicist

Medical Physics Research Team

Division of Heavy Ion Clinical Researches

Korea Heavy Ion Medical Accelerator Project (KHIMA Project)

KOREA INSTITUTE of RADIOLOGICAL & MEDICAL SCIENCES (KIRAMS)

#215-4 Gongneung-dong Nowon-gu

Seoul 139-709, Korea

Tel: 82-2-970-1737

Fax: 82-2-970-1962

Mobile:82-10-6366-9161

E-Mail: leeronaldo_at_naver.com (with big file), leeronaldo_at_kirams.re.kr

======================================================================

From: Dr. Vittorio Boccone [mailto:dr.vittorio.boccone_at_ieee.org]

Sent: Tuesday, September 02, 2014 5:32 AM

To: leeronaldo_at_naver.com; fluka-discuss_at_fluka.org >> "fluka-discuss_at_fluka.org"

Subject: Re: [fluka-discuss]: How to calculate LET(linear energy transfer) with voxel-by-voxel basis

Dear Kyung-Nam Lee,

I assume you already went through the manual Section 13.2.2

First of all, I hope to ask when the routine(comscw.f) is called

specifically.

I mean scoring time, namely, whether the routine is called after end of

"event" or end of "each interaction" or not.

Is it depend on used scoring command(e.g. USRBIN, USRYIELD, USRBDX) ??

You enable the comsw routine with from the WHAT(6) of USERWEIG.

It's as a matter of fact a weighting factor which is calculated at scoring time per each deposition step and modifies directly the value scored with USRBIN etc...

Also, I would like to ask how can I get the deq99.f(user routine for calc.

of effective dose) file.

/deq99c.f)

So, could you attach this file when you reply ?

Effective dose is now calculated by default using the AUXSCORE card. We will correct the manual to removed the part mentioning of the usage of the deq99.f routine which is at the moment strongly deprecated.

Because I am a beginner for modifying user routines, It will be great help

for me if I understand the contents of the file.

Then, I can know how to calculate LET by using useful "COMMON variable". In addition, I would like to actively listen to any kind of your advice about calculating Dose Averaged LET(my final goal in this process) with

FLUKA user routine.

I think you can just score the LET with USRYIELD and you don't really need to recalculate it (unless you need to do it on purpose).

Please check http://www.fluka.org/web_archive/earchive/new-fluka-discuss/6829.html and the other LET related question on the forum, they might give you more answers and clarify a bit the LET scoring option you have.

It might not have been a very generous reply... but I hope it clarifies a bit the scoring of the LETs

Vittorio

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Received on Wed Sep 03 2014 - 08:00:50 CEST

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