Med Phys
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Ultrasound imaging is becoming increasingly important in prostate brachytherapy. In high-dose-rate (HDR) real-time planning procedures the definition of the implant needles is often performed by transrectal ultrasound. This article describes absolute measurements of the visibility and accuracy of manual detection of implant needle tips and compares measurement results of different biplane ultrasound systems in transversal and longitudinal (i.e., sagittal) ultrasound modes. ⋯ The results show that ultrasound-based needle tip definition in sagittal viewing mode is accurate. The inter- and intraobserver errors should, however, be taken into account. A lower gain setting of the ultrasound system reduces the intraobserver error.
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This study was designed to investigate the effect of prostatic edema on various dosimetric quality indices following transperineal permanent 131Cs seed implant. Thirty-one patients with early prostate cancer, who received 131Cs permanent seed implant, were included in this study. Each patient received a prescribed dose of 115 Gy from the implant. ⋯ Therefore, improvement in V100 and FD90 due to edema decay does not improve the physical dose delivery to the prostate. It is important to note that at the time of 131Cs implant, the effect of edema must be accounted for when defining the seed positions. Implants performed based only on the guidance of a preimplant volume study would result in poor dosimetric results for 131Cs implants.