Introduction to permanent implants

Interstitial prostate brachytherapy was first performed by Barringer in 1915 [29-31]. Its first widespread adoption occurred in the 1970s, when the retropubic method was popularized [32]. A laparotomy was done for lymph node dissection and exposure of the prostate. Io-dine-125 sources were implanted under direct visualization. The procedure was technically difficult to perform, in part because of limited working space in the pelvis. As a result, retropubic implantation lost popularity in the 1980s [33]. Instead, ultrasound-guided permanent prostatic implantation emerged in the early 1980s and has spread all over the world. The ultrasound-guided transperineal technique was initially described by Holm and coworkers in 1983 [34]. Transrectal ultrasound (TRUS) allowed visualization of the needle location within the prostate, facilitating real-time read-justments of needle position as necessary. Implants could be computer preplanned using transverse ultrasound images. Transperineal implants also could be done percutaneously on an outpatient basis, without laparotomy. Combined with modern, computer-based treatment planning, technological advances allowed for higher quality outpatient prostate brachytherapy [35].

Brachytherapy offers substantial biologic advantages over EBRT in terms of dose localization and higher biologic doses. A modification of the time, dose, and fractionation tables has been made to allow interconvertability between beam radiation and low-dose-rate brachytherapy [36]. There are also substantial practical advantages of brachytherapy, including vastly shorter treatment times and lower costs. These practical advantages have helped maintain widespread interest in brachytherapy, despite continuous improvements in beam radiation. Although enthusiasm remains high in some quarters, there are still vexing discrepancies in reported cure rates and morbidities. It is becoming clearer that such discrepancies result partly from different technical expertise and patient management policies [37]. Brachytherapy, like surgery, is operator-dependent and outcomes vary with skill and experience.

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