Computed axial tomography (CAT) contribution for dosimetry and treatment evaluation in lung cancer

The use of computed axial tomography (CAT) scans in postoperative patients with lung cancer was studied to evaluate its contribution in dosimetry and to study the late effects of irradiation. Comparisons were made between the treatment planning generated from CAT scan data and that obtained from two orthogonal radiographs. Both methods offered a good approximation but with orthogonal radiographs possible mediastinal and lung shift could not be seen and the dose delivered to the spinal cord was overestimated. A control CAT scan performed 6 to 18 months after treatment showed a lung fibrosis that was strictly correlated with the treatment planning and related with doses and volume treated. CAT scans allowed more accurate treatment planning.