The Evaluated Value Of Physics Parameters For The Patients Radiation Pneumonitis Treated With Intensity Modulated Radiation Therapy

Objective:To evaluate the predictive value of physical parameters related to acute radiation pneumonitis (ARP) in esophagus carcinoma treated with intensity modulated radiation therapy (IMRT), so as to provide a better related standard to reduce the incidence of ARP when evaluating an IMRT plan of esophagus carcinoma.Methods:72 esophagus carcinoma patients treated with IMRT(with or without concurrent chemotherapy), between January 2013 and June 2015, were retrospectively reviewed. According to Common Terminology Criteria for Adverse Events (CTCAE) version 4.0, univariate and multivariate logistic regression analyses were performed to evaluate the relationship between factors, included clinical and dosimetric, and symptomatic ARP(grade 2 or more) or Severe ARP (Grade 3 or more),while dosimetric parameters included Dv (relative doses of lung irradiated more than a threshold volume of 10%-80% at increments of 10%), Vd (relative volumes of lung receiving more than a threshold dose of 5～40Gy at increments of 5Gy) and MLD (mean lung dose).Results:After radiation,16.7% and 6.9% of the patients suffered from symptomatic ARP and Severe ARP respectively. Univariate analysis showed that the MLD, V5-40Gy at increments of 5Gy,and D40%～80% at increments of 10% were associated with ARP grade 2 or more. Then the physical factors affecting the ARP grade 3 or more included D60,D70,D80,V5,V10,V15 and MLD. However, the clinical factors render, age, chemotherapy based on cisplatin, position of the tumor, weight lose (no less than 5 kg),complications with double lungs and received surgeon or not were not significantly associated with the ARP grade 2 or more. In multivariate analysis, V5 (p=0.023) were the most significant factors possibly associated with ARP grade 3 or more.Conclusions:1.The patients suffering from esophagus carcinoma treated with IMRT have a low incidence of ARP induced by radiotherapy; 2.We should pay more attentions to the influence of the physical parameters when assessing the radiation plan; 3.The size of lung volume receiving low doses is associated with the incidence of ARP, but also possibly with the severity of ARP of the esophagus carcinoma patients treated with IMRT.