IMRT delivery verification using indigenously developed diagonal water phantom

Intensity modulated field leads to steep dose gradients on the edges of the target volume and OARs. Because of this, delivery errors can have severe effects on the outcome of a treatment and on tumor control. Many methods of delivery verification of IMRT have been described in the literature, including the use of MOSFETs, EPID and combination of TLDs, radio chromic and radiographic film, gels, diodes, and ion chambers. Radiographic film may still be one of the best dosimeters for IMRT verification due to its ability to integrate dose and its good spatial resolution. The conventional use of the film has always been a configuration in which square blocks are used and multiple films are staked either parallel (XZ plane) or perpendicular (XY Plane) to the beam. So at a time any two coordinates of the three-dimensional volume have been used for verification. To overcome this problem the authors designed a new square phantom with diagonal cavity to place the film. This plane ensures all the three co-ordinates (X,Y,Z) at a time for verification