“…In the past, the results achieved with conventional external-beam radiotherapy were poor [11]. In contrast to conventional radiotherapy, three-dimensional conformal radiotherapy (3DRT) based on a three-dimensional treatment planning system (3DPS) provides the possibility to deliver higher radiation doses to the tumor simultaneously sparing normal tissues [2,5,7,9,13,15,16,20]. The advantage of 3DPS is not only to optimize the treatment technique but also to take tissue inhomogeneities into account for dose calculation.…”