Department of Radiotherapy, Cancer Center, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China.
Key Laboratory of Radiation Biology of Fujian Higher Education Institutions, The First Affiliated Hospital, Fujian Medical University, Fuzhou, China.
J Appl Clin Med Phys. 2022 Jul;23(7):e13612. doi: 10.1002/acm2.13612. Epub 2022 May 30.
We explored the effects of geometrical topological properties of tumors such as tumor length and "axial cross-sectional area (ACSA)" of tumors (planning target volume [PTV] volume /PTV length) on the dosimetric parameters of organs at risk (lung and heart) in patients with esophagus cancer (EPC) treated by way of intensity-modulated radiation therapy (IMRT), so as to provide a guideline for the dosimetric limitation for organs at risk in IMRT treatment.
A retrospective analysis was done on 103 cases of patients with EPC who were treated by IMRT from November 2010 to August 2019, in which PTV-G stood for the externally expanded planning target volume (PTV) of the gross tumor volume (GTV) and PTV-C for the externally expanded volume of the clinical target volume (CTV). A linear regression model was employed to analyze the several pairs of correlation: the 1st one between the relative length of tumors (PTV length/lung length) and pulmonary dose-volume parameters, the 2nd one between ACSA of tumors and pulmonary dose-volume parameters, the 3rd one between PTV length and the dosimetric parameters of the heart, and the last one between ACSA of tumors and the dosimetric parameters of the heart.
(i) There was a strong positive correlation between the relative length of tumors (PTV length/lung length) and V (p < 0.001, r = 0.73), and V (p < 0.001, r = 0.66) of the lung. There was a moderate positive correlation between the relative length of tumors and V (p < 0.001, r = 0.44) of the lung, and a weak positive correlation between the relative length of tumors and V (p < 0.001, r = 0.39) of the lung. (ii) There was a strong positive correlation between ACSA of tumors (PTV volume/PTV length) and V (p < 0.001, r = 0.67) of the lung, a moderate positive correlation between ACSA of tumors and V (p <0.001, r = 0.51) of the lung, and a weak positive correlation between ACSA of tumors and V (p = 0.019, r = 0.23) of the lung, yet there was not an obvious correlation between ACSA of tumors and V p > 0.05) of the lung. (iii) There was a moderate positive correlation between PTV length and V (p < 0.001, r = 0.58), and D (p < 0.001, r = 0.52) of the heart, yet there was no obvious correlation between ACSA of tumors and D and V of the heart (p > 0.05).
(i) Compared with the high-dose region of the lung, the relative length of tumors (PTV length/lung length) has a greater impact on the low-dose region of the lung. The linear regression equation of scatter plot showed that when the relative length of tumors increased by 0.1, the lung dose-volume parameters of V , V , V , and V increased by approximately 5.37%, 3.59%, 1.05%, and 1.08%, respectively. When PTV length increased by 1 cm, D and V of the heart increased by approximately 153.6 cGy and 2.03%, respectively. (ii) Compared with the low-dose region of the lung, the value of ACSA of tumors (PTV volume/PTV length) has a greater impact on the high-dose region of the lung. However, the value of ACSA of tumors has no significant effect on the dosimetric parameters of the heart (D and V ). The linear regression equation of scatter plot showed that when ACSA of tumors increased by 10 cm , the lung dose-volume parameters of V , V and V increased by approximately 3.11%, 3.37%, and 4.01%, respectively.
我们探讨了肿瘤的几何拓扑特性，如肿瘤长度和肿瘤的“轴向截面积（ACSA）”（计划靶区[PTV]体积/PTV 长度）对食管癌（EPC）患者调强放疗（IMRT）中危及器官（肺和心脏）剂量学参数的影响，为 IMRT 治疗中危及器官的剂量学限制提供指导。
对 2010 年 11 月至 2019 年 8 月期间 103 例接受 IMRT 治疗的 EPC 患者进行回顾性分析，其中 PTV-G 代表大体肿瘤体积（GTV）的外部扩展计划靶区（PTV），PTV-C 代表临床靶区（CTV）的外部扩展体积。采用线性回归模型分析了几对相关性：第一对是肿瘤相对长度（PTV 长度/肺长度）与肺剂量-体积参数之间的相关性，第二对是肿瘤 ACSA 与肺剂量-体积参数之间的相关性，第三对是 PTV 长度与心脏剂量学参数之间的相关性，第四对是肿瘤 ACSA 与心脏剂量学参数之间的相关性。
（i）肿瘤相对长度（PTV 长度/肺长度）与肺的 V （p<0.001，r=0.73）和 V （p<0.001，r=0.66）呈强正相关。肿瘤相对长度与肺的 V （p<0.001，r=0.44）呈中度正相关，与肺的 V （p<0.001，r=0.39）呈弱正相关。（ii）肿瘤 ACSA（PTV 体积/PTV 长度）与肺的 V （p<0.001，r=0.67）呈强正相关，与肺的 V （p<0.001，r=0.51）呈中度正相关，与肺的 V （p=0.019，r=0.23）呈弱正相关，但与肺的 V 无明显相关性（p>0.05）。（iii）PTV 长度与心脏的 V （p<0.001，r=0.58）和 D （p<0.001，r=0.52）呈中度正相关，但与心脏的 D 和 V 无明显相关性（p>0.05）。
（i）与肺的高剂量区相比，肿瘤相对长度（PTV 长度/肺长度）对肺的低剂量区影响更大。散点图线性回归方程显示，当肿瘤相对长度增加 0.1 时，肺的剂量-体积参数 V 、 V 、 V 、和 V 分别增加约 5.37%、3.59%、1.05%和 1.08%。当 PTV 长度增加 1cm 时，心脏的 D 和 V 分别增加约 153.6cGy 和 2.03%。（ii）与肺的低剂量区相比，肿瘤 ACSA（PTV 体积/PTV 长度）对肺的高剂量区影响更大。然而，肿瘤 ACSA 对心脏的剂量学参数（D 和 V ）没有显著影响。散点图线性回归方程显示，当肿瘤 ACSA 增加 10cm 时，肺的剂量-体积参数 V 、 V 和 V 分别增加约 3.11%、3.37%和 4.01%。
