From e.a.gh72 at gmail.com Sat Oct 3 01:23:10 2020 From: e.a.gh72 at gmail.com (Ali ghorbanian) Date: Sat, 3 Oct 2020 08:53:10 +0330 Subject: [Rtk-users] RTK library for Fan Beam CT Scan In-Reply-To: References: Message-ID: Thanks a lot. On Wed, Sep 30, 2020 at 6:42 PM Simon Rit wrote: > Dear Ali, > No need to send the same message more than once. It's possible to do > fan-beam by managing the interpolations. For voxel-based backprojection, > RTK does a bilinear interpolation on the detector so you need to add a line > above and below each 1D projection. There is an example here > (with an old wrapping but the > idea is similar with the new ones). For ray-driven projection, you can use > 1D projections but you need to reconstruct 3 slices instead of 1. > Simon > > On Tue, Sep 29, 2020 at 1:19 PM Ali ghorbanian wrote: > >> Hi, >> Can we use the RTK library for Fan Beam CT Scan? >> Good luck. >> _______________________________________________ >> Rtk-users mailing list >> Rtk-users at public.kitware.com >> https://public.kitware.com/mailman/listinfo/rtk-users >> > -------------- next part -------------- An HTML attachment was scrubbed... URL: From simon.rit at creatis.insa-lyon.fr Tue Oct 6 05:36:37 2020 From: simon.rit at creatis.insa-lyon.fr (Simon Rit) Date: Tue, 6 Oct 2020 11:36:37 +0200 Subject: [Rtk-users] Insufficient Data For Proper Parker Weighting In-Reply-To: References: Message-ID: Hi, I have finally taken the time to reproduce and correct for the bug, see https://github.com/SimonRit/RTK/pull/380. Sorry for the delay... Simon On Tue, Jun 30, 2020 at 6:45 AM Brani Rusanov wrote: > Sorry I forgot to mention, the Parker message only appears when > reconstructing with CUDA enabled. > > ------------------------------ > *From:* Simon Rit > *Sent:* Tuesday, 30 June 2020 5:22 AM > *To:* Brani Rusanov > *Cc:* rtk-users at public.kitware.com > *Subject:* Re: [Rtk-users] Insufficient Data For Proper Parker Weighting > > Hi, > No, I don't really understand what you're describing. It's probably easier > if you can share the RTK geometry file and the header of your projection > images (no need to share the data, I'll simulate some). > Thanks, > Simon > > On Mon, Jun 29, 2020 at 5:51 AM Brani Rusanov > wrote: > > Hi Simon, > > Sorry for the late reply, I have been quite busy recently. > My projections are 1024x768. I cropped the largest dimension and noticed > that "half the beam angle" value decreases slightly, gets close to the > value 9.951, but with further reduction in dimension size the beam angle > suddenly jumps to ~20 degrees (observed value during reconstruction). So > cropping the projection does not seem to solve the problem. Do you have any > ideas how to fix this? > > If you require any geometry or projection files, I would be happy to send > them over. > > Kind regards, > Brani > ------------------------------ > *From:* Simon Rit > *Sent:* Monday, June 15, 2020 8:59:19 PM > *To:* Brani Rusanov > *Cc:* rtk-users at public.kitware.com > *Subject:* Re: [Rtk-users] Insufficient Data For Proper Parker Weighting > > Hi, > You are getting this because RTK detects that the scan is too short. > Parker weighting requires pi + the fan-angle to be able to reconstruct > exactly the central slice of your scan. Check here > > how this is calculated in RTK. > Possible solutions are cropping the projections to reduce the fan angle. > I'm not sure what are the consequences but they'll probably be small since > not much is missing in your case. It's even likely that RTK could be > improved by discretizing differently the integral in parker weighting, in > which case you'd get enough projections. > Simon > > > On Mon, Jun 15, 2020 at 10:56 AM Brani Rusanov > wrote: > > > Hi, > > I am attempting to reconstruct Varian raw cone-beam data. The specific > type of scan is a short scan, 200 degrees generating 501 projections. > During reconstruction I get the message: ?you do not have enough data for > proper Parker weighting (short scan) Delta is 9.951 degrees and should be > more than half the beam angle I.e. 11.2359 degrees.? > > Since I have not generated the geometry myself, rather, used a pre-set > Varian protocol, I am unsure why I get this error. > > How could I rectify this issue? Furthermore, what consequences are there > to not applying a Parker weighting? > > The geometry header is attached. > > Your response is greatly appreciated, > Brani > _______________________________________________ > Rtk-users mailing list > Rtk-users at public.kitware.com > https://public.kitware.com/mailman/listinfo/rtk-users > > > -------------- next part -------------- An HTML attachment was scrubbed... URL: