Comparison of ultrasound and implanted seed marker prostate localization methods: Implications for image-guided radiotherapy

Conclusions: Ultrasound and SM methods suggest different shifts. US data reveal greater systematic/random error vs. SM data. The US data suggest larger PTV expansion margins (∼9 mm) are necessary for US IGRT vs. SM IGRT (∼3 mm). The hypotheses that US and SM methods suggest similar shifts and that the mean US/SM three-dimensional distance discrepancy is ≤5 mm are rejected.