Absorbed-Dose Computations for Inhomogeneous Media in Radiation-Treatment Planning Using Differential Scatter-Air Ratios*

摘要

In clinical radiotherapy, the presently available methods of dose computation in the presence of inhomogeneities are approximate and their applicability to actual situations is therefore limited. Recent developments in computed tomography have given a new level of precision in internal structure localization and tissue characterization in terms of electron density. Motivated by these new advances, we have developed a method for calculating dose distributions in three dimensions in the presence of inhomogeneities of arbitrary shapes and sizes. Our method, applicable for treatment planning in megavoltage therapy, can perform well for beams of either regular or irregular cross-section. Unlike most current treatment-planning schemes, our proposed method appeals directly to established physical principles governing the interaction of electromagnetic radiations with matter at the atomic level.