RT Journal Article SR Electronic T1 The Effect of Source Size on the Buildup Factor Calculation of Absolute Volume JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 1319 OP 1322 VO 26 IS 11 A1 Jeffry A. Siegel YR 1985 UL http://jnm.snmjournals.org/content/26/11/1319.abstract AB