Verification of lung dose in an anthropomorphic phantom calculated by the collapsed cone convolution method

Verification of calculated lung dose in an anthropomorphic phantom is perfo rmed using two dosimetry media. Dosimetry is complicated by factors such as variations in density at slice interfaces and appropriate position on CT s canning slice to accommodate these factors. Dose in lung for a 6 MV and 10 MV anterior-posterior field was calculated with a collapsed cone convolutio n method using an ADAC Pinnacle, 3D planning system. Up to 5% variations be tween doses calculated at the centre and near the edge of the 2 cm phantom slice positioned at the beam central axis were seen, due to the composition of each phantom slice. Validation of dose was performed with LiF thermolum inescent dosimeters (TLDs) and X-Omat V radiographic film. Both dosimetry m edia produced dose results which agreed closely with calculated results nea rest their physical positioning in the phantom. The collapsed cone convolut ion method accurately calculates dose within inhomogeneous lung regions at 6 MV and 10 MV x-ray energy.