Al Feghali Karine A, Wu Qixue Charles, Devpura Suneetha, Liu Chang, Ghanem Ahmed I, Wen Ning Winston, Ajlouni Munther, Simoff Michael J, Movsas Benjamin, Chetty Indrin J
Department of Radiation Oncology, Henry Ford Hospital, 2799 W. Grand Boulevard, Detroit, MI, USA.
Department of Clinical Oncology, Alexandria University, Alexandria, Egypt.
Clin Transl Radiat Oncol. 2020 Feb 11;22:1-8. doi: 10.1016/j.ctro.2020.02.004. eCollection 2020 May.
To investigate the correlation between normal lung CT density changes with dose accuracy and outcome after stereotactic body radiation therapy (SBRT) for patients with early stage non-small-cell lung cancer (NSCLC).
Thirty-one patients (with a total of 33 lesions) with non-small cell lung cancer were selected out of 270 patients treated with SBRT at a single institution between 2003 and 2009. Out of these 31 patients, 10 patients had developed radiation pneumonitis (RP). Dose distributions originally planned using a 1-D pencil beam-based dose algorithm were retrospectively recomputed using different algorithms. Prescription dose was 48 Gy in 4 fractions in most patients. Planning CT images were rigidly registered to follow-up CT datasets at 3-9 months after treatment. Corresponding dose distributions were mapped from planning to follow-up CT images. Hounsfield Unit (HU) changes in lung density in individual, 5 Gy, dose bins from 5 to 45 Gy were assessed in the peri-tumoral region. Correlations between HU changes in various normal lung regions, dose indices (V20, MLD, generalized equivalent uniform dose (gEUD)), and RP grade were investigated.
Strong positive correlation was found between HU changes in the peri-tumoral region and RP grade (Spearman's r = 0.760; < 0.001). Positive correlation was also observed between RP and HU changes in the region covered by V20 for all algorithms (Spearman's r ≥ 0.738; < 0.001). Additionally, V20, MLD, and gEUD were significantly correlated with RP grade ( < 0.01). MLD in the peri-tumoral region computed with model-based algorithms was 5-7% lower than the PB-based methods.
Changes of lung density in the peri-tumoral lung and in the region covered by V20 were strongly associated with RP grade. Relative to model-based methods, PB algorithms over-estimated mean peri-tumoral dose and showed displacement of the high-dose region, which correlated with HU changes on follow-up CT scans.
探讨早期非小细胞肺癌（NSCLC）患者立体定向体部放射治疗（SBRT）后正常肺组织CT密度变化与剂量准确性及治疗结果之间的相关性。
从2003年至2009年在单一机构接受SBRT治疗的270例患者中选出31例（共33个病灶）非小细胞肺癌患者。这31例患者中，10例发生了放射性肺炎（RP）。最初使用基于一维铅笔束的剂量算法规划的剂量分布，采用不同算法进行回顾性重新计算。大多数患者的处方剂量为48 Gy，分4次给予。将治疗前的计划CT图像与治疗后3至9个月的随访CT数据集进行刚性配准。将相应的剂量分布从计划CT图像映射到随访CT图像。在肿瘤周围区域评估5至45 Gy的单个5 Gy剂量区间内肺密度的Hounsfield单位（HU）变化。研究不同正常肺区域的HU变化、剂量指数（V20、平均肺剂量（MLD）、广义等效均匀剂量（gEUD））与RP分级之间的相关性。
肿瘤周围区域的HU变化与RP分级之间存在强正相关（Spearman秩相关系数r = 0.760；P < 0.001）。对于所有算法，RP与V20覆盖区域的HU变化之间也观察到正相关（Spearman秩相关系数r≥0.738；P < 0.001）。此外，V20、MLD和gEUD与RP分级显著相关（P < 0.01）。基于模型算法计算的肿瘤周围区域的MLD比基于铅笔束的方法低5%至7%。
肿瘤周围肺组织及V20覆盖区域的肺密度变化与RP分级密切相关。相对于基于模型的方法，铅笔束算法高估了肿瘤周围平均剂量，并显示出高剂量区域的位移，这与随访CT扫描上的HU变化相关。
