Finding circle in binary image (R, not matlab) How would I extract the circular area of a binary image which looks like:

The two rods emerging from the side of the circle are noise.
I know of the hough transform in Matlab. However, I am using R and can't seem to find anything similar.
Ideas anyone?
On page 4 of this document describing the R PET package, there's documentation of the Hough transformation. That's probably what you want.