Radiation techniques for head and neck tumors

Purpose: A technique that combines some advantages of conforming techniques for advanced oro- and hypopharyngeal carcinomas is proposed. The aim is to increase the dose homogeneity in the target volume relative to lateral opp osed fields. Methods and materials: This publication compares conforming radiation techn iques based on standard equipment, standard linear accelerator setup and co mmercially available planning software with lateral opposed fields. More ad vanced conformal techniques reported in the literature are taken into accou nt in a semi-quantitative manner. Our standard method uses an are rotation, sparing the spinal cord. In contrast to earlier methods of this type, the resulting dose deficit in the vicinity of the spine is compensated by stati c lateral wedged fields. Dose distributions for 25 consecutive patients wer e planned. Results: The conforming techniques were found to produce more homogeneous d ose distributions than lateral opposed fields. In the planning target volum e (PTV) (mean: 940 cm(3)) a standard deviation of dose of 4.6% was achieved . Ninety five percent of the PTV were enclosed by the 90% isodose. The maxi mal spinal cord dose was limited to 45 Gy. The dose distributions of these techniques could compete with literature data on advanced techniques (the p ublished dose-volume histogram (DVHs) of PTVs were evaluated). At the linea r accelerator time for realization took 14 min on average. The planning tim e is 1-4 h (mean: less than 2 h). Conclusion: A rotational technique applicable with standard equipment is pr esented. Dose coverage of target volumes is improved, while the spinal cord is spared. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.