Abstract
A 6-field technique using lateral beams in conformal radiotherapy was developed for patients with bilateral supraclavicular lymph node metastasis of lung cancer. The possibility of using this technique in practice was evaluated. Six fields with the same isocenter point (IP) were arranged. Two fields using anterior-posterior opposed beams involved all of the planning target volume (PTV). The next 2 fields using off-cord oblique beams involved the PTV inferior to the IP. The remaining 2 fields using lateral opposed beams, that shielded the spinal cord, involved the PTV superior to the IP. The oblique 2 fields and lateral 2 fields were connected using a half-beam technique. In 6 patients with non-small-cell lung cancer (NSCLC, n = 4) or small-cell lung cancer (SCLC, n = 2), treatment re-planning based on this technique was performed. This technique was applicable in 4 patients with NSCLC, in whom the general criteria of radiotherapy for lung cancer were met. In 2 patients with SCLC, the cumulative volume of lung that received more than 20 Gy exceeded 37% of the total lung volume. This technique was usable in 67% of the patients and was not necessarily contraindicated in the other 33%.