[Rtk-users] Tomosynthesis Reconstruction using RTK

[Chao Wu]

Agree, sdd==sid=700*cos(theta_in_the_picture). Another suspicious thing may
be the projection shift (-isox,0). If the input projection are plain images
from a real system without origin definition in its format, then the
projection shift may be (0,-isoy) instead, with projection origin at the
corner pixel.

2014-11-04 17:55 GMT+01:00 Simon Rit <simon.rit at creatis.insa-lyon.fr>:

> Hi,
> When the source moves, along which axis of the detector is it? I would
> have expected it to move along the X axis.
> There is another option to set the geometry that might be easier for you,
> Reg23ProjectionGeometry
> <http://www.openrtk.org/Doxygen/classrtk_1_1Reg23ProjectionGeometry.html>.
> In any case, your scheme is wrong and I agree with Louie, you should think
> of the source parameters as the coordinates if all angles are set to 0 so
> in your case sdd==sid.
> Simon
>
> On Tue, Nov 4, 2014 at 5:17 PM, louie L <ghostcz at hotmail.com> wrote:
>
>> Hi Andria,
>>
>> Can you explain the setup with some more details? Which is the axis of
>> rotation?
>> I think if the isocenter is on the detector, the sid should be set equal
>> to the sdd.
>>
>> Best regards,
>> Louie
>>
>> Greetings from my iOS!
>>
>> On 04 Nov 2014, at 17:04, Hadjipanteli Andria (ROYAL SURREY COUNTY
>> HOSPITAL NHS FOUNDATION TRUST) <andria.hadjipanteli at nhs.net> wrote:
>>
>>
>>  Dear all,
>>
>> We used the FirstReconstruction.cxx code with minor changes to
>> reconstruct a digital breast tomosynthesis stack of projections acquired
>> using a Hologic Selenia Dimenions system. Unfortunately, the reconstructed
>> image does not look as expected.
>>
>> The characteristics of the geometry of the system are that the detector
>> remains stationary while the x-ray tube moves around a centre of rotation
>> located at the detector (see attached diagram). The changes we made to
>> FirstReconstruction.cxx so that it represents the Hologic Geometry are that
>> the sdd and sourceOffesetY both vary as a function of the rotation of the
>> source (sid*sin(angleTheta) and sid*cos(angleTheta) respectively) while in
>> all cases gantryAngle= 0, sid = 700 mm and isox = -detectorWidth/2. Our
>> geometry definition is:
>>
>> geometry->AddProjection(700,sdd,0,-isox,0,0,0,0,sourceOffsetY);
>>
>> Please let me know if you have any ideas on what we might be doing
>> wrong.
>>
>> Thank you for your help.
>>
>> Kind regards,
>>
>> Andria
>>
>>
>>
>>
>>
>>
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>> <NCCPM_TomoGeometry.pdf>
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