IMRT 2017

IMRT CONCERNS ON SMALL FIELD DOSIMETRY AND BEAM MODELLING IMRT requires the addition of these small fields ( segments ) delivered with irregular shapes and non - equilibrium conditions to treat target volumes using optimization routines. These segments are commonly off-axis and with overlapping penumbra over the treatment volume.

There is no clear consensus definition as to what constitutes a small field , but in practice, field sizes lower than or equal to 3 cm x 3 cm present dosimetry issues that require special attention (Das et al ., 2008) There are some questions that must be of concern for an appropriate dosimetry (dose measurement and beam modelling in treatment planning system) whose effect in narrow beams is more critical (Das et al ., 2008, IPEM 2010)