BIOLOGICALLY EFFECTIVE DOSE DISTRIBUTION BASED ON THE LINEAR-QUADRATIC MODEL AND ITS CLINICAL RELEVANCE
BIOLOGICALLY EFFECTIVE DOSE DISTRIBUTION BASED ON THE LINEAR-QUADRATIC MODEL AND ITS CLINICAL RELEVANCE
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DOI：
10.1016/0360-3016(95)00162-r
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发表时间：
1995-09-30
影响因子：
7
通讯作者：
WITHERS, HR
中科院分区：
文献类型：
--
作者：
LEE, SP;LEU, MY;WITHERS, HR
目的：基于物理剂量分布的放疗方案不一定完全反映各种分治方案下的生物效应。在过去的十年中，线性二次（LQ）模型已经成为量化放射治疗生物效应的方便工具。在这项工作中，我们着手构建基于LQ模型的生物定向剂量分布显示机制。方法和材料：已经开发了一种计算机程序，将市售治疗计划系统计算的物理剂量分布转换为生物有效剂量（BED）分布，并根据理论计算进行了验证。该软件接受用户输入的每个感兴趣的结构的生物参数（线性和二次剂量反应和再种群动力学参数），以及治疗方案因素（分数，分数剂量和治疗时间）。然后结合解剖结构呈现二维BED显示。此外，为了便于临床医生与传统分馏方案进行直观的比较，也允许将BED转换为标准化等有效剂量（NID）。结果：两个病例说明了我们的工具在临床实践中的应用。(a)采用正交楔形对x射线束治疗上颌窦肿瘤，可以量化同侧下颌骨的生物学效应，从而很好地说明了所谓的“双麻烦”效应。(b)对于典型的使用10毫伏x射线的四场均匀加权前列腺治疗，物理剂量学预测在两场/天和四场/天交替设置之间股骨颈部的剂量相当。然而，我们的BED显示显示，对于两场/天的方案，BED大约高出21%。如果采用3:2（前-后/后-前（AP/PA）：双侧对侧（BLO））剂量加权治疗，可以消除对股骨颈的过量剂量。对于Co-60光束，每天交替两场，1:1设置的BED增加更为明显（26%）。结论：在临床放疗实践中，构建生物学取向剂量分布是可行的。在给定治疗方案的基础上，对物理剂量分布与生物对应剂量之间的不一致进行了量化。非处方点BED的计算机显示大大增强了该工具的通用性。尽管在临床放疗中常规使用这种方法应谨慎进行，主要取决于已发表的生物学参数的准确性，但它可以帮助临床医生根据特定的分离方案得出最佳的治疗方案，或将其用作临床研究结果分析的定量工具。
Purpose: Radiotherapy plans based on physical dose distributions do not necessarily entirely reflect the biological effects under various fractionation schemes. Over the past decade, the linear-quadratic (LQ) model has emerged as a convenient tool to quantify biological effects for radiotherapy. In this work, we set out to construct a mechanism to display biologically oriented dose distribution based on the LQ model.Methods and Materials: A computer program that converts a physical dose distribution calculated by a commercially available treatment planning system to a biologically effective dose (BED) distribution has been developed and verified against theoretical calculations. This software accepts a user's input of biological parameters for each structure of interest (linear and quadratic dose-response and repopulation kinetic parameters), as well as treatment scheme factors (number of fractions, fractional dose, and treatment time). It then presents a two-dimensional BED display in conjunction with anatomical structures. Furthermore, to facilitate clinicians' intuitive comparison with conventional fractionation regimen, a conversion of BED to normalized isoeffective dose (NID) is also allowed.Results: Two sample cases serve to illustrate the application of our tool in clinical practice. (a) For an orthogonal wedged pair of x-ray beams treating a maxillary sinus tumor, the biological effect at the ipsilateral mandible can be quantified, thus illustrates the so-called ''double-trouble'' effects very well. (b) For a typical four-field, evenly weighted prostate treatment using 10 MV x-rays, physical dosimetry predicts a comparable dose at the femoral necks between an alternate two-fields/day and four-fields/day setups. However, our BED display reveals an approximate 21% higher BED for the two-fields/day scheme. This excessive dose to the femoral necks can be eliminated if the treatment is delivered with a 3:2 (anterio-posterior/posterio-anterior (AP/PA):bilaterally opposed (BLO)) dose weighting. With Co-60 beams, the increase of BED with alternate two-fields/day, 1:1 setup was even more pronounced (26%).Conclusion: We have demonstrated the feasibility of constructing a biologically oriented dose distribution for clinical practice of radiotherapy. The discordance between physical dose distributions and the biological counterparts based on the given treatment schemes was quantified. The computerized display of BED at nonprescription points greatly enhanced the versatility of this tool. Although the routine use of this implementation in clinical radiotherapy should be cautiously done, depending largely on the accuracy of the published biological parameters, it may, nevertheless, help the clinicians derive an optimal treatment plan with a particular fractionation scheme or use it as a quantitative tool for outcome analysis in clinical research.