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)

ABSTRACT

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.