Morrill S M, Langer M L, Lane R G, Rosen I I
University of Texas Medical Branch, Galveston 77550.
Int J Radiat Oncol Biol Phys. 1994 Oct 15;30(3):699-706. doi: 10.1016/0360-3016(92)90958-k.
There is general agreement that tissue density correction factors improve the accuracy of dose calculations. However, there is disagreement over the proper heterogeneity correction algorithm and a lack of clinical experience in using them. Therefore, there has not been widespread implementation of density correction factors into clinical practice. Furthermore, the introduction of optimized conformal therapy leads to new and radically different treatment techniques outside the clinical experience of the physician. It is essential that the effects of tissue density corrections are understood so that these types of treatments can be safely delivered.
In this paper, we investigate the effect of tissue density corrections on optimized conformal type treatment planning in the thorax region. Specifically, we study the effects on treatment plans optimized without type treatment planning in the thorax region. Specifically, we study the effects on treatment plans optimized without tissue density corrections, when those corrections are applied to the resulting dose distributions. These effects are compared for two different conformal techniques.
This study indicates that failure to include tissue density correction factors results in an increased dose of approximately 5-15%. This is consistent with published studies using conventional treatment techniques. Additionally, the high-dose region of the dose distribution expands laterally into the uninvolved lung and other normal structures. The use of dose-volume histograms to compare these distributions demonstrates that treatment plans optimized without tissue density corrections lead to an increased dose to uninvolved normal structures. This increase in dose often violates the constraints used to determine the optimal solution.
The neglect of tissue density correction factors can result in a 5-15% increase in the delivered dose. In addition, suboptimal dose distributions are produced. To benefit from the advantages of optimized conformal therapy in the thorax, tissue density correction factors should be used.
人们普遍认为组织密度校正因子可提高剂量计算的准确性。然而，对于合适的不均匀性校正算法存在分歧，并且在使用这些算法方面缺乏临床经验。因此，组织密度校正因子尚未在临床实践中广泛应用。此外，优化适形治疗的引入带来了医生临床经验之外的全新且截然不同的治疗技术。了解组织密度校正的效果对于安全实施这类治疗至关重要。
在本文中，我们研究了组织密度校正对胸部区域优化适形治疗计划的影响。具体而言，我们研究了对未进行组织密度校正而优化的胸部区域治疗计划的影响，当将这些校正应用于所得剂量分布时。针对两种不同的适形技术比较了这些影响。
本研究表明，未纳入组织密度校正因子会导致剂量增加约5% - 15%。这与使用传统治疗技术的已发表研究结果一致。此外，剂量分布的高剂量区域会横向扩展至未受累的肺及其他正常结构。使用剂量 - 体积直方图比较这些分布表明，未进行组织密度校正而优化的治疗计划会导致未受累正常结构的剂量增加。这种剂量增加常常违反用于确定最优解的约束条件。
忽视组织密度校正因子会导致所给予的剂量增加5% - 15%。此外，会产生次优的剂量分布。为了从胸部优化适形治疗的优势中获益，应使用组织密度校正因子。
