Dosimetric evaluation of a pencil-beam algorithm for electrons employing a two-dimensional heterogeneity correction

摘要: The accuracy of a pencil-beam algorithm for electrons employing two-dimensional heterogeneity correction is demonstrated by comparing calculation with measurement. Ionization measurements have been made in water phantom variety non-standard geometries. Geometries to demonstrate the effect an extended treatment distance, sloping skin surface, and irregular surface selected. Additionally, thermoluminescent dosimeters used measure distributions tissue-substitute phantoms, which were designed from individual patient computerized tomographic scans. Three scans selected: (1) diffuse hystiocytic lymphoma left buccal mucosa retromolar trigone; (2) squamous cell carcinoma nose at columnella ; (3) maxillary antrum. Results algorithm's ability simultaneously account isodose shifting as result internal heterogeneities sidescatter non-equilibrium caused lateral discontinuities anatomy. shown generally be accurate within +/- 4% volume or 4 mm regions sharp dose gradients found penumbra distal edge beam. Examples greater disagreement are their physical interpretation discussed.