Localizing the spinal cord in oblique off-cord lung boosts

We present a method to accurately localize the spinal cord in oblique projections on plain radiographs. Utilizing a CT scan done with the patient in the treatment position, a template is generated to localize the spinal cord. The technique involves analyzing successive axial CT slices and locating cord position relative to the beam central axis. The template is then placed on the simulator fiducial plate at the time of verification simulation. Cord position is documented in the "beam's eye view" on the radiograph. Utilizing this technique, our radiation oncologists are more comfortable defining the medial field border in oblique setups. In most cases, this technique will minimize the perceived need to add superfluous spinal cord blocks that compromise tumor dose.