AbstractID: 8169 Title: Moving Target, Dynamic Treatment: Is the Respiratory Gating,
A Solution?
Tumor motion due to respiration poses several challenges to radiation oncology especially in the era of conformal therapy, dose escalation, and IMRT where accurate target localization is paramount. It is difficult to predict the dosimetric consequences of dynamic treatments to a moving target. The doses in lung or upper abdominal lesions from a dynamic wedge or IMRT treatment, for example, may result in severe cold and hot spots inside the tumor. Although respiratory gating technology was originally reported in 1989, it is only recently that it has gained renewed interest. This study investigates the ability of Varian’s Real Time
Positioning Management system to eliminate dose uncertainties due to target motion. To study the effects of dynamic treatments on a moving target, a moving film phantom was constructed. This solid water phantom accommodates radiographic, and radiochromic films. The phantom is mounted on a platform that moves vertically in a sinusoidal motion. CT scans of the moving phantom is obtained with and without gating. The plans were performed on ADAC pinnacle planning system. Dosimetric measurements were performed with and without respiratory gating at 90
° gantry angle and the film placed perpendicular to the beam. The resulting films were analyzed utilizing Radiological Imaging Technology software. Several scenarios such as enhanced dynamic wedges, step and shoot
IMRT, dynamic IMRT were evaluated and are discussed. Significant changes in dose distributions within the moving target were noted. These results will be presented.