A typical transverse slice showing the distributions of 125I seeds and isodose curves after seed implantation from CT scan. The isodose lines shown are 300 Gy (brown), 160 Gy (red), 100 Gy (blue), 80 Gy (green) and 40 Gy (yellow). PTV and 125I seeds are shown in light grey circle and blue dots, respectively.