BRACHYTHERAPY FOR THE NEXT CENTURY - USE OF IMAGE-BASED TREATMENT PLANNING

Three-dimensional treatment planning systems used extensively for exte rnal-beam treatments have recently been applied for use in brachythera py. Localization of structures in 3D from imaging studies integrated i nto computerized systems for planning of implants and evaluation allow s 3D dose distributions to be indexed to the patient's anatomy. Correl ation of target volume and dose distribution permits planning of confo rmal dose distributions, which maximizes the dose to the target volume while avoiding dose to normal tissue. Imaging during the implantation process can improve the delivery of the dose distribution planned pri or to implantation, which may translate into improved outcome. Postimp lant imaging scans can be compared to preimplant planning, providing f eedback on the error in source placement and ultimately improving impl antation. Application of image-based planning and delivery for ultraso und-guided transperineal prostate implantation is widespread. The firs t part of this report will discuss in detail a major research effort a t our institution to understand and improve the prostate implant proce ss. In the last half of our report, we will describe 3D treatment plan ning for gynecological implants. Problems with traditional implant pla nning and delivery procedures (perhaps still used today) and how image -based treatment planning and delivery can improve the implant process will be presented. (C) 1998 by Radiation Research Society.