Olsen C C, Welsh J, Kavanagh B D, Franklin W, McCarter M, Cardenes H R, Gaspar L E, Schefter T E
Department of Radiation Oncology, University of Colorado, Denver, Aurora, CO 80045-000508, USA.
Int J Radiat Oncol Biol Phys. 2009 Apr 1;73(5):1414-24. doi: 10.1016/j.ijrobp.2008.07.032. Epub 2008 Nov 5.
To describe the histologic and volumetric changes in normal liver tissue after stereotactic body radiotherapy (SBRT) for liver metastases.
Pre- and post-SBRT imaging studies were analyzed to evaluate the effect of SBRT on normal liver volume (NLV) in 15 patients treated in a prospective clinical trial. Two other patients underwent exploratory surgery after SBRT and histologic analyses of the irradiated liver were performed to characterize the pathologic effects of SBRT.
In the 15 patients studied quantitatively, the total NLV had decreased transiently at 2-3 months after SBRT and then began to regenerate at 3-8 months after SBRT. The median NLV reduction at the maximal observed effect was 315 cm(3) (range, 125-600) or 19% (range, 13-33%). Among the several dosimetric parameters evaluated, the strongest linear correlation was noted for the NLV percentage receiving 30 Gy as a predictor of maximal NLV reduction (r(2) = 0.72). The histologic changes observed 2 and 8 months after SBRT demonstrated distinct zones of tissue injury consistent with localized veno-occlusive disease.
The well-demarcated focal parenchymal changes after liver SBRT (demonstrated both radiographically and histologically) within the high-dose zone are consistent with a threshold dose-induced set of phenomena. In contrast, the more global effect of NLV reduction, which is roughly proportional to whole organ dose parameters, resembles more closely an effect determined from radiobiologically parallel architecture. These observations suggest that modeling of normal tissue effects after liver SBRT might require different governing equations for different classes of effects.
描述立体定向体部放疗（SBRT）治疗肝转移瘤后正常肝组织的组织学和体积变化。
对15例接受前瞻性临床试验治疗的患者进行SBRT前后的影像学研究，以评估SBRT对正常肝体积（NLV）的影响。另外2例患者在SBRT后接受了 exploratory 手术，并对受照射的肝脏进行了组织学分析，以确定SBRT的病理效应。
在15例进行定量研究的患者中，SBRT后2 - 3个月总NLV短暂下降，然后在SBRT后3 - 8个月开始再生。最大观察效应时NLV的中位数减少量为315 cm³（范围为125 - 600）或19%（范围为13 - 33%）。在评估的几个剂量学参数中，接受30 Gy的NLV百分比与最大NLV减少量的预测指标之间存在最强的线性相关性（r² = 0.72）。SBRT后2个月和8个月观察到的组织学变化显示出与局限性静脉闭塞性疾病一致的不同组织损伤区域。
肝SBRT后在高剂量区内明确界定的局灶性实质变化（影像学和组织学均有显示）与阈值剂量诱导的一系列现象一致。相比之下，NLV减少的更整体效应大致与全器官剂量参数成比例，更类似于从放射生物学平行结构确定的效应。这些观察结果表明，肝SBRT后正常组织效应的建模可能需要针对不同类型的效应采用不同的控制方程。
