[Rtk-users] FW: Elekta CBCT Reconstrution

[Simon Rit]

Hi,
I also seem to have difficulties with the mailing list, I'll ask the admin,
sorry about that.
The conversion is based on this code:
https://github.com/SimonRit/RTK/blob/master/include/rtkElektaSynergyLookupTableImageFilter.hxx#L43-L56
There is nothing fancy except that the values are reverted compared to the
usual scale (maximum value has maximum attenuation) and that the first and
last values take the same values.
Simon

On Tue, Jul 6, 2021 at 11:04 AM Hamed Hooshangnejad <hamed at jhu.edu> wrote:

> Hi Simon
>
>
> Sorry to bother you again
>
>
> I subscribed to mailing lists but still my email was rejected so I decided
> to reply to our previous email.
>
> As i told you, I am new to RTK and c++ and I am trying to reconstruct
> Elekta projections by using my own code, however, using the original
> projections I could not get a good reconstruction. I noticed that in RTK
> before the reconstruction is done a look up table normalization is applied
> to the image, but I could not find out how this look up table value is
> determined or where I can find the values. Essentially I need the
> calibrated for attenuation projections or projections with air having the
> maximum intensity so I calibrate it by -log(I/I_air) so wondering if you
> can explain it to me or if there is any resources I can use.
>
>
>
>
> Thank you so much
>
> Hamed
>
>
>
>
> Sent via the Samsung Galaxy S10+, an AT&T 5G Evolution capable smartphone
> Get Outlook for Android <https://aka.ms/AAb9ysg>
> ------------------------------
> *From:* Hamed Hooshangnejad <hamed at jhu.edu>
> *Sent:* Friday, July 2, 2021 8:57:01 AM
> *To:* Simon Rit <simon.rit at creatis.insa-lyon.fr>
> *Cc:* rtk-users at openrtk.org <rtk-users at openrtk.org>
> *Subject:* RE: FW: Elekta CBCT Reconstrution
>
>
> Thank you so much Simon
>
> I actually tried to send it to the mailing list but it said “Your message
> has been rejected”.
>
> But thank you I try to see if I can resolve the issue
>
>
>
> Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for
> Windows 10
>
>
>
> *From: *Simon Rit <simon.rit at creatis.insa-lyon.fr>
> *Sent: *Friday, July 2, 2021 4:48 AM
> *To: *Hamed Hooshangnejad <hamed at jhu.edu>
> *Cc: *rtk-users at openrtk.org
> *Subject: *Re: FW: Elekta CBCT Reconstrution
>
>
>
> Hi,
>
> Please post your questions on RTK's mailing list (cc). The algorithm to
> account for offset detectors is DisplacedDetectorImageFilter
> <https://nam02.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.openrtk.org%2FDoxygen%2Fclassrtk_1_1DisplacedDetectorImageFilter.html&data=04%7C01%7Chamed%40jhu.edu%7C247f9d01e76f4979ebb508d93d36367c%7C9fa4f438b1e6473b803f86f8aedf0dec%7C0%7C0%7C637608125330025533%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=yzc5vcLHP4KJJGtvGmfYWuo46jZ%2FvxCdI1fqTRYFFqY%3D&reserved=0>.
> The reference we used is in the documentation but there are previous
> references solving the same matter (e.g.
> https://doi.org/10.1016/0895-6111(96)00031-6). To detect that it is
> dealing with such a situation and needs to apply some weighting prior to
> reconstruction, RTK computes the field of view for each side of the
> detector, see code here
> <https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FSimonRit%2FRTK%2Fblob%2Fmaster%2Finclude%2FrtkDisplacedDetectorImageFilter.hxx%23L136-L144&data=04%7C01%7Chamed%40jhu.edu%7C247f9d01e76f4979ebb508d93d36367c%7C9fa4f438b1e6473b803f86f8aedf0dec%7C0%7C0%7C637608125330035532%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=QMcRb4WS93MKIUgdTMqmzS4jYmISoL2jDPJmkofpx%2BQ%3D&reserved=0>
> .
>
> I hope it helps,
>
> Simon
>
>
>
> On Fri, Jul 2, 2021 at 3:26 AM Hamed Hooshangnejad <hamed at jhu.edu> wrote:
>
> Hi Simon
>
>
>
> I saw your messages on RTK helping other people. I was just wondering if
> you can also help me with this. I am a new user of rtk, and I have some
> questions regarding the Elekta CBCT reconstruction. We are using the
> original projections and elekta generated -xframe file with information
> about gantry angles and panel offset. However, there is no explicit
> information about the field of view but the reconstruction works for both
> small and medium FOV so I am wondering how RTK finds out what FOV should be
> used.
>
> When I do the reconstruction using other codes I always get this ring
> artifact (following figure), I am wondering what causes this issue (I
> suspect it is a FOV related issue. )
>
>
>
> Thank you so much SImon
>
> Hamed
>
>
>
> Sent from Mail
> <https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgo.microsoft.com%2Ffwlink%2F%3FLinkId%3D550986&data=04%7C01%7Chamed%40jhu.edu%7C247f9d01e76f4979ebb508d93d36367c%7C9fa4f438b1e6473b803f86f8aedf0dec%7C0%7C0%7C637608125330035532%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=jlqfRGeAVmrAT6M33z%2F0WolF%2BEMzTCW1bbBn1aZyHxI%3D&reserved=0>
> for Windows 10
>
>
>
>
>
>
>
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