Junhai Wen Tianfang Li Zhengrong Liang Ray-driven analytical fan-beam SPECT reconstruction with nonuniform attenuation. 629-632 2002 conf/isbi/2002 ISBI http://dx.doi.org/10.1109/ISBI.2002.1029336 db/conf/isbi/isbi2002.html#WenLL02