Validity of lung correction algorithms

Our studies have compared the "effective tissue-air ratio (TAR) method" (ICRU Report No. 24), "equivalent TAR method," and the "generalized Batho method" (currently used by the TP-11 computer treatment planning system) with measured results for different energy photon beams using two lung inhomogeneities to simulate a lateral chest field. Significant differences on the order of 3%-15% were found when comparing these various methods with measured values.