ifanbeam and iradon

Hi, I tried to use ifanbeam to provide Ct images but when I use this:

D=600; dtheta = 2; dsensor=0.1 ;

[Farc,Fangles] = ifanbeam(R,D,'FanSensorSpacing',dsensor,'FanRotationIncrement',dtheta,'Interpolation','spline','OutputSize',256);

I got an unusual image but by iradon I=iradon(R,0:179,'spline',256); I got a right one(of course with artifact), dose any one know about it, it seems there is a relation between FanSensorSpacing and D, thanks for any hints and guide, thanks in advance.

regards

Answer 1

[Steve Eddins]

The documentation for fanbeam has geometry diagrams that might be helpful to you.

[Tom Reynolds]

Thanks Steve I read about them and also about:If 'FanSensorSpacing' is not specified, the default is the smallest value implied by 'ParallelSensorSpacing' such that

If 'FanSensorGeometry' is 'arc', 'FanSensorSpacing' is

180/PI*ASIN(PSPACE/D)

where PSPACE is the value of 'ParallelSensorSpacing'.

If 'FanSensorGeometry' is 'line', 'FanSensorSpacing' is

D*ASIN(PSPACE/D) and [D*sin(min(FAN_ANGLES)),D*sin(max(FAN_ANGLES))]

but it seems some thing is not right, if you will be interested I could send you two images that I got from iradon and ifanbeam. againg thanks for your consideration.