The biological rationale for the use of brachytherapy, which is underg
oing a significant resurgence in the United States, is reviewed with e
mphasis on low dose rate (LDR brachytherapy). Some of the newer altern
atives that have recently been developed, such as pulsed dose rate (PD
R) brachytherapy, are discussed. (C) 1997 Wiley-Liss, Inc.