RESUMO
PURPOSE: Measurement of transmission dose is useful for in vivo dosimetry. In this study, previous algorithm for estimation of transmission dose was modified for use in cases with tissue deficit. MATERIALS AND METHODS: The beam data was measured with flat solid phantom in various conditions of tissue deficit. New algorithm for correction of transmission dose for tissue deficit was developed by physical reasoning. The algorithm was tested in experimental settings with irregular contours mimicking breast cancer patients using multiple sheets of solid phantoms. RESULTS: The correction algorithm for tissue deficit could accurately reflect the effect of tissue deficit with errors within +-1.0% in most situations and within +-3.0% in experimental settings with irregular contours mimicking breast cancer treatment set-up. CONCLUSION: Developed algorithm could accurately reflect the effect of tissue deficit and irregularly shaped body contour on transmission dosimetry.