The impact of technological advances on the evolution of 3D conformal brachytherapy for early prostate cancer.
Review
Overview
abstract
Permanent implantation of I-125 and Pd-103 seeds is one of the widely used treatment options for the early stage prostate cancer with minimum normal tissue complications and long-term local control of the tumor. This is possible because of several technological advances made in the past decade to better understand the procedural aspects of implantations with the desired clinical outcome and with acceptable morbidities. In addition, with the widespread use of PSA testing, more widely disseminated information about prostate cancer and increased patient awareness, over 70% of patients are diagnosed early with localized disease and therefore are candidates for definitive local therapy. Delineation of soft tissue structures including the prostate, rectum, urethra and bladder has become more accurate with the use of imaging modalities including Ultrasound and MRI, with or without the CT. A re-evaluation of the dosimetric parameters of the radioactive sources has lead to a more precise estimate of the dose delivered to the prostate and the associated critical normal structures. Technological improvements in the post implant dosimetry have helped to understand the factors, which makes an implant a "good implant" or a "poor implant". Intraoperative treatment planning with on line dosimetry is emerging as one of the best approaches for prostate brachytherapy. In addition, better software is now available producing dose-volume histograms with 3D target and normal tissue reconstruction. The combination of seed implant followed by IMRT would provide scope for differentially boosting the regions under-dosed because of uncontrollable and unexpected reasons during the implant and unsuspected micro extensions of the tumor.
