Brachytherapy oncology treatment systems and methods are provided. One such system and method employs a catheter or tandem and a mobile balloon device having an enclosed inner volume and an internal surface with an internal perimeter size larger than the external surface perimeter size and adequate to allow sliding longitudinal movement between the catheter or tandem and the mobile balloon device. The mobile balloon device has a radiation dose delivery tube that is at or moves by inflation to a strategic radiation dose delivery location for brachytherapy. An embodiment allows for a multi-part catheter or tandem having a detachable distal section suitable for retaining within a body cavity such as the uterus, both during radiation treatment and during recovery time between radiation treatments. This distal portion can be intended for single-patient use and be disposed of after completion of a radiation treatment session having multiple radiation dose treatment times. One or both of real time in vivo detection and monitoring and hypertherapy features can be included.
