1. B.E. Patt, A. DelDuca, R. Dolin and C. Ortale, IEEE Trans. Nucl. Sci., NS-33 (1), 523 (1986).
2. K. Zanio, Revue de Physique Appliqueé 12, 343 (1977).
3. H.B. Barber, H.H. Barrett, E.L. Dereniak, N.E. Hartsough, D.L. Perry, P.C.T. Roberts, M.M. Rogulski, J.M. Woolfenden and E.T. Young, Phys. Medica 9, 135 (1993).
4. J.F. Butler, S.J. Friesenhahn, C. Lingren, B. Apotovsky, R. Simchon, F.P. Doty, W.L. Ashburn and W. Dillon, Conf. Record of the 1993 IEEE Nucl. Sci. Symp. and Med. Imag. Conf., ed. L.A. Klaisner, (Piscataway, NJ: IEEE, 1994), p. 1, 565.
5. E. Raiskin and J. Butler, IEEE Trans. Nucl. Sci., NS-35 (1), 82 (1988).