OBJECTIVE: Needles are guided to their proper anatomic locations in sonographically guided percutaneous prostate brachytherapy by a mechanical system (template). A quality assurance procedure has been designed to test this template's alignment with the needle position overlay grid displayed in the sonographic image. METHODS: A mechanical arrangement was designed to position the needles properly with respect to the prostate probe's transducer in a liquid-filled test tank. Two liquids were tested: tap water and an ethylene glycol mixture with an acoustic velocity of 1540 m/s. Needle images with the superposed grid were analyzed for needle placement accuracy. RESULTS: The tap water produced misregistration of the needle images. The ethylene glycol mixture yielded images of vertical and horizontal needle positions accurate to 0.3 and 1 mm, respectively. Also, the importance of selecting the lowest possible equipment echo amplitude dynamic range in these tests was shown. CONCLUSIONS: This quality assurance test with the ethylene glycol mixture will permit accurate alignment of the brachytherapy needle position overlay grid for each separate transrectal probe used.
OBJECTIVE: Needles are guided to their proper anatomic locations in sonographically guided percutaneous prostate brachytherapy by a mechanical system (template). A quality assurance procedure has been designed to test this template's alignment with the needle position overlay grid displayed in the sonographic image. METHODS: A mechanical arrangement was designed to position the needles properly with respect to the prostate probe's transducer in a liquid-filled test tank. Two liquids were tested: tapwater and an ethylene glycol mixture with an acoustic velocity of 1540 m/s. Needle images with the superposed grid were analyzed for needle placement accuracy. RESULTS: The tapwater produced misregistration of the needle images. The ethylene glycol mixture yielded images of vertical and horizontal needle positions accurate to 0.3 and 1 mm, respectively. Also, the importance of selecting the lowest possible equipment echo amplitude dynamic range in these tests was shown. CONCLUSIONS: This quality assurance test with the ethylene glycol mixture will permit accurate alignment of the brachytherapy needle position overlay grid for each separate transrectal probe used.