O'Donoghue J A
Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.
J Nucl Med. 1999 Aug;40(8):1337-41.
This article describes a method of assessing the biologic consequences of nonuniform dose distributions produced in tumors by biologically targeted radionuclide therapy. The analysis is based on a simple mathematical model that assumes all tumor cells are uniformly radiosensitive.
Using the linear-quadratic radiobiologic model, it is possible to represent an absorbed dose distribution by a biologically effective dose (BED) volume histogram (BVH). The Laplace transform of the BVH yields an equivalent uniform biologically effective dose. This is a one-number value that fully describes the biologic effect of a nonuniform absorbed dose distribution. In this article, for the purposes of exposition, nonuniform BED distributions are represented by normal distributions.
Nonuniform absorbed dose distributions are inefficient in sterilizing tumors and become proportionately less effective as the mean dose increases. The loss in effectiveness is most severe for radiosensitive tumors.
Several approaches may alleviate the consequences of dosimetric nonuniformity. These include the use of smaller targeting molecules, radionuclides with longer emission ranges, fractionated administration of biologically targeted radionuclide therapy and combined modality treatments.
本文描述了一种评估生物靶向放射性核素治疗在肿瘤中产生的非均匀剂量分布的生物学后果的方法。该分析基于一个简单的数学模型，该模型假定所有肿瘤细胞具有均匀的放射敏感性。
使用线性二次放射生物学模型，可以通过生物等效剂量（BED）体积直方图（BVH）来表示吸收剂量分布。BVH的拉普拉斯变换产生等效均匀生物等效剂量。这是一个单一数值，可完全描述非均匀吸收剂量分布的生物学效应。在本文中，为便于阐述，非均匀BED分布用正态分布表示。
非均匀吸收剂量分布在使肿瘤失活方面效率低下，并且随着平均剂量增加，其有效性成比例降低。对于放射敏感肿瘤，有效性损失最为严重。
几种方法可减轻剂量学不均匀性的后果。这些方法包括使用更小的靶向分子、发射范围更长的放射性核素、生物靶向放射性核素治疗的分次给药以及联合治疗模式。
