Ahuja S D, Stroup S L, Bolin M G
Med Phys. 1981 Mar-Apr;8(2):215-9. doi: 10.1118/1.594936.
Values of tissue-air ratio (TAR) and tissue-maximum ratio (TMR) have been calculated with the photon energy-fluence absorption dose model, at depths d greater than dn (depth of dose normalization) in a homogeneous water phantom, for Co-60 gamma-ray, and 4, 6, 10, 14, and 45 MVp x-ray beams of EQS (the side of the equivalent square) up to 20 cm. It has been found that by (i) slightly altering the formula for the depth modification factor so that it depends on the difference (d -- dn) rather than d alone; and (ii) permitting E, the effective energy of the beam, to vary with EQS for some x-ray beams, it is possible for the model to reproduce within 2.5% the measured data at depths d greater than dn, on TAR, TMR and PDD (the central axis percent depth dose), for any source to surface distance.
利用光子能量注量吸收剂量模型，在均匀水模体中，对于钴 - 60伽马射线以及等效方形边长（EQS）达20厘米的4、6、10、14和45兆伏峰值的X射线束，在深度d大于剂量归一化深度dn处，计算了组织空气比（TAR）和组织最大比（TMR）的值。研究发现，通过（i）略微改变深度修正因子的公式，使其取决于差值（d - dn）而非仅取决于d；以及（ii）对于某些X射线束，允许束流的有效能量E随EQS变化，该模型能够在任何源皮距下，在深度d大于dn处，在TAR、TMR和中心轴百分深度剂量（PDD）方面，将测量数据再现至2.5%以内。
