Three dimensional conformal radiation therapy in pediatric XXXX .

@entity1 @entity135 @entity242 @entity5 @entity980
PURPOSE: We evaluated the utility of three dimensional (3D) treatment planning in the management of @entity1 with @entity135 . METHODS AND MATERIALS: Five @entity1 with parameningeal @entity980 were referred for treatment at our radiation oncology center from May 1990 through January 1993. Each @entity1 was evaluated, staged, and treated according to the Intergroup @entity980 Study. @entity1 were immobilized and underwent a computed tomography scan with contrast in the treatment position. @entity5 and normal tissues were identified with assistance from a diagnostic radiologist and defined in each slice. The @entity1 were then planned and treated with the assistance of a 3D treatment planning system. A second plan was then devised by another physician without the benefit of the 3D volumetric display. The target volumes designed with the 3D system and the two-dimensional (2D) method were then compared. The dosimetric coverage to @entity5 , @entity5 plus margin, and normal tissues was also compared with the two methods of treatment planning. RESULTS: The apparent size of the gross @entity5 volume was underestimated with the conventional 2D planning method relative to the 3D method. When margin was added around the gross @entity5 to account for microscopic extension of disease in the 2D method, the expected area of coverage improved relative to the 3D method. In each circumstance, the minimum dose that covered the gross @entity5 was substantially less with the 2D method than with the 3D method. The inadequate dosimetric coverage was especially pronounced when the necessary margin to account for subclinical disease was added. In each case, the 2D plans would have delivered substantial dose to adjacent normal tissues and organs, resulting in a higher incidence of significant complications. CONCLUSIONS: 3D conformal radiation therapy has a demonstrated advantage in the treatment of @entity242 of the head and neck. The improved dosimetric coverage of the @entity5 and its margin for subclinical extensions may result in improvement in local control of these @entity5 . In addition, lowering of radiation dose to adjacent critical structures may help lower the incidence of adverse late effects in @entity1 .
