Effect of tumor and normal lung volumes on the lung volume-dose parameters of IMRT in non-small-cell lung cancer

OBJECTIVES: To explore the effect of tumor and normal lung volumes on lung volume-dose parameters in patients with non-small-cell lung cancer (NSCLC) who had undergone intensity-modulated radiation therapy (IMRT). METHODS: The clinical data of 208 patients with NSCLC who underwent radical IMRT between June 2014 and June 2018 were retrospectively analyzed. A regression model curve was used to evaluate the effect of tumor and normal lung volumes on normal lung relative volumes receiving greater than 5 and 20 Gy (V5, V20), on mean lung dose (MLD), and on absolute volumes spared from greater than 5 and 20 Gy (AVS5, AVS20). RESULTS: The V5, V20, and MLD of the bilateral lung were fitted to a quadratic equation curve with the change in tumor volume, which increased initially and then decreased when the tumor volume increased. The V5, V20, and MLD of the lung reached their apex when the tumor volumes were 288.07, 341.69, and 326.83 cm3, respectively. AVS5 and AVS20 decreased in a logarithmic curve with an increase in tumor volume. The V5, V20, and MLD of the small normal lung volume group were all significantly higher than those of the large normal lung volume group (p<0.001, p=0.004, p=0.002). However, the AVS5 and AVS20 of the small normal lung volume group were all significantly lower than those of the large normal lung volume group (p<0.001). CONCLUSION: The effects of tumor volume and normal lung volume on dose-volume parameters should be considered. AVS5 is an important supplementary dose limitation parameter for patients whose tumor volume exceeds a certain boundary value (approximately 300 cm3).

Effect of tumor volume on pulmonary dose-volume parameter by intensity-modulated radiation therapy in non-small cell lung cancer / 中南大学学报(医学版)

Objective:To explore the effectof tumor volume on pulmonary dose-volume parameters by intensity-modulated radiation therapy (IMRT) in non-small cell lung cancer (NSCLC),and to provide a basis for pulmonary dose parameters in IMRT treatment.Methods:A total of 204 patients with NSCLC received IMRT were retrospectively analyzed from June,2009 to October,2013.The prescribed dose of planning target volume (PTV) for primary tumor was 60-66Gy (2.00-2.25 Gy,27-33 times in all).The fractional volume percent of the lung received a dose ＞5 or 20 Gy (V5,V20),and absolute volume of lung received a dose ＜5 Gy (AVS5).The mean lung dose (MLD) in normal tissues were analyzed.Regression model curve was used to analyze them along with the change of primary tumor volume.Results:With the increase in lung tumor volume,the V5,V20 and MLD presented quadratic equation curve,and AVS5 presented logarithmic equation.When the tumor volume,less than a certain value (294.6,283.2,304.9 cm3,respectively),the V5,V20 and MLD increased with tumor size and presented an increased quadratic curve;when the tumor volume was higher than a certain value (294.6,283.2,304.9 cm3 respectively),the V5,V20 and MLD was declined.The AVS5 was declined in a logarithmic curve along with the increase of tumor volume.Conclusion:With the increase in lung tumor volume,the change in rule ofV5,V20,MLD and AVS5 is not completely equivalent.When the tumor volume exceeds a certain boundary value (about 300 cubic centimeter),the corresponding tumor diameter is about 7-8 cm.In addition to the focus on pulmonary V5,V20 and MLD,we should also pay more attention to AVS5 restrictions in establishment ofIMRT in NSCLC.