Development of multifield three‐dimensional conformal radiotherapy of lung cancer using a total lung dose/volume histogram

A measurable improvement in the efficacy of the three‐dimensional radiotherapy (RT) of primary lung cancer patients with unresectable disease will require the development of a technique that increases the therapeutic ratio of dose delivered to the tumor volume relative to functional lung. A full course of definitive RT dose was delivered to six consecutive primary lung cancer patients using multiple fields with treatment portals tightly conformed to the tumor shape in beams‐eye‐view, using multileaf collimation. For each patient, a treatment planning dose/volume histogram (DVH) was constructed considering the most anatomically normal tissues in both the ipsilateral and contralateral lungs. When compared to a standard anteroposterior‐posteroanterior (AP‐PA) treatment plan followed by parallel‐opposed oblique fields with conventional blocks, the five‐field conformal technique yielded a significantly lower integral lung dose as determined by cumulative DVH data. We compared the data for total lung capacity in cubic centimeters from the treatment planning DVH with that obtained by pulmonary function tests and found good concordance. The present RT technique and patient evaluation program should provide a valuable approach toward improving the quality of life in irradiated lung cancer patients, and may also guide efforts by which to escalate the dose to a tumor volume in the chest. © 1995 Wiley‐Liss, Inc.