Strigari L, Orlandini L C, Andriani I, d'Angelo A, Stefanacci M, Di Nallo A M, Benassi Marcello
Laboratory of Medical Physics and Expert Systems, Regina Elena National Cancer Institute, Rome, Italy.
Phys Med Biol. 2008 Sep 21;53(18):5045-59. doi: 10.1088/0031-9155/53/18/013. Epub 2008 Aug 22.
The low-dose-rate brachytherapy technique has proven suitable for the management of prostate cancer. However, published data generally report the clinical outcome and the minimum peripheral dose (mPD) to the target volume and not the actual dose distribution in patients. To this end, modern guidelines recommend the use of specific dose and volume indices describing dose distribution throughout the target. The introduction of a method, based on the standard linear quadratic model and Poisson statistics, entitled the F-factor allows the TCP from different DVHs to be calculated, by using the TCP from a uniform dose distribution as the reference. The F-factor sensitivity against radiobiological parameters and influence of the DVH were evaluated. We applied the F-formula on the post-plan DVHs of 58 patients treated with (125)I permanent seed implant brachytherapy for localized prostate cancer. F shows a strong correlation with dosimetric parameters already reported as significant predictors of the biochemical outcome.
低剂量率近距离放射治疗技术已被证明适用于前列腺癌的治疗。然而，已发表的数据通常报告的是临床结果以及靶区的最小周边剂量（mPD），而非患者体内的实际剂量分布。为此，现代指南建议使用描述整个靶区剂量分布的特定剂量和体积指标。一种基于标准线性二次模型和泊松统计的方法——F因子被引入，通过将均匀剂量分布的肿瘤控制概率（TCP）作为参考，能够计算不同剂量体积直方图（DVH）的TCP。评估了F因子对放射生物学参数的敏感性以及DVH的影响。我们将F公式应用于58例接受¹²⁵I永久性粒子植入近距离放射治疗局限性前列腺癌患者的计划后DVH。F与已被报道为生化结果重要预测指标的剂量学参数密切相关。
