Identification of pubic arch interference in prostate brachytherapy:: Simplifying the transrectal ultrasound technique

Purpose We report a simplified technique allowing identification of pubic arch interference (PAI) using transrectal ultrasound (TRUS). Methods and materials Fifty consecutive brachytherapy patients implanted using a two-stage technique were studied. The pubic arch was outlined using a marker pen on the ultrasound monitor screen during the dose planning ultrasound. Where pubic arch interference (PAI) was identified attempted needle passage was used to confirm PAI (n = 3). Results Mean time to perform PAI assessment was 90 s. Three of 50 patients had PAI, which was confirmed by attempted needle passage. No patients required modification to the implant plan during the implant procedure. Conclusions TRUS reliably identifies PAI. This simple technique may be used with any TRUS scanner and avoids the need for CT scanning or specific software to identify PAI. Our low incidence of PAI may be related to lower prostate volumes at implantation due to patient selection, neoadjuvant androgen deprivation, or improved patient positioning.