A new technique for irradiating thoracic inlet tumors

Tumors of the thoracic inlet create a dilemma in radiation therapy treatment planning. It is difficult to give tumoricidal doses in this area because of the limitations of spinal cord tolerance. Opposed anterior-posterior fields, oblique fields and electron beam fields give inadequate dose distribution. A patient position and four-field treatment technique has been developed which allows us to give doses of 6000 + rad to tumors in the thoracic inlet, and limits the spinal cord dose to 4000 rad. A 25 MeV photon beam is used for opposed anterior-posterior and lateral fields. The lateral fields are treated with the patient supine, the upper arms are raised and rotated posteriorly, the scapula is pulled medially, the elbows are flexed, the forearms and hands are raised above and behind the head. Following the axis of the upper esophagus, the caudal end of the field is more posterior than the cephalad end of the field. As computerized axial tomography becomes available more readily and provides us with better knowledge of the anatomy in the thoracic inlet, this treatment position and technique may prove very useful.