Laboratory of Medical Physics and Expert System, Regina Elena Cancer Institute, Rome, Italy.
J Exp Clin Cancer Res. 2011 May 9;30(1):52. doi: 10.1186/1756-9966-30-52.
An advantage of the Intensity Modulated Radiotherapy (IMRT) technique is the feasibility to deliver different therapeutic dose levels to PTVs in a single treatment session using the Simultaneous Integrated Boost (SIB) technique. The paper aims to describe an automated tool to calculate the dose to be delivered with the SIB-IMRT technique in different anatomical regions that have the same Biological Equivalent Dose (BED), i.e. IsoBED, compared to the standard fractionation.
Based on the Linear Quadratic Model (LQM), we developed software that allows treatment schedules, biologically equivalent to standard fractionations, to be calculated. The main radiobiological parameters from literature are included in a database inside the software, which can be updated according to the clinical experience of each Institute. In particular, the BED to each target volume will be computed based on the alpha/beta ratio, total dose and the dose per fraction (generally 2 Gy for a standard fractionation). Then, after selecting the reference target, i.e. the PTV that controls the fractionation, a new total dose and dose per fraction providing the same isoBED will be calculated for each target volume.
The IsoBED Software developed allows: 1) the calculation of new IsoBED treatment schedules derived from standard prescriptions and based on LQM, 2) the conversion of the dose-volume histograms (DVHs) for each Target and OAR to a nominal standard dose at 2Gy per fraction in order to be shown together with the DV-constraints from literature, based on the LQM and radiobiological parameters, and 3) the calculation of Tumor Control Probability (TCP) and Normal Tissue Complication Probability (NTCP) curve versus the prescribed dose to the reference target.
调强放射治疗（IMRT）技术的一个优势是可以使用同时整合boost（SIB）技术在单次治疗中向 PTV 提供不同的治疗剂量水平。本文旨在描述一种自动工具，用于计算在具有相同生物等效剂量（BED）的不同解剖区域中使用 SIB-IMRT 技术的剂量，即与标准分割相比的等剂量（IsoBED）。
基于线性二次模型（LQM），我们开发了允许计算与标准分割等效的治疗计划的软件。主要的放射生物学参数来自文献中的数据库，该数据库可以根据每个机构的临床经验进行更新。特别是，将根据目标体积的α/β比值、总剂量和每次剂量（通常为标准分割的 2 Gy）来计算每个靶区的 BED。然后，在选择参考靶区（即控制分割的 PTV）后，将为每个靶区计算提供相同 IsoBED 的新总剂量和剂量。
开发的 IsoBED 软件允许：1）根据 LQM 计算来自标准处方的新 IsoBED 治疗计划；2）将每个靶区和 OAR 的剂量体积直方图（DVHs）转换为名义标准剂量，即 2 Gy 每次剂量，以便与文献中的 DV 约束一起显示，基于 LQM 和放射生物学参数；3）计算参考靶区的规定剂量下的肿瘤控制概率（TCP）和正常组织并发症概率（NTCP）曲线。
