The design of any positron emission tomograph involves some compromises. In particular, the simultaneous goals of high sensitivity and good resolution have resulted in circular ring systems using relatively large crystals and rotation/wobbling motions. The wobbling motion unfortunately results in nonuniform linear sampling. In this paper we investigate the effect of wobble diameter and number of wobble positions on reconstructed image quality. Computer simulations were performed with noise-free and Poisson noise projection data. For the best choice of wobble parameters, image artifacts were less than 1% and the noise level was increased by less than 5%. Noticeably worse performance was obtained when using some parameters suggested by others. Copyright © 1981 by The Institute of Electrical and Electronics Engineers, Inc.