| Objections The heart and its chambers were contoured respectively and dose-volume parameter were evaluated in Dose-Volume Hitogram(DVH) of radiothorapy plan. Combined evaluation of dose-volume parameter mensioned above with the status of acute radiation induced pneumnia we aim to explore: 1)whether heart irradiation can be a prediction of radiotherapy induced pneumonia; 2)To comfirm the cut-off of heart chambers in thorax irradition if heart irradition can predict the occurrence of radition pneumonis.Methods Patients with thorax malignant carcinoma diagnosed and treated in our department from January 2013 to July 2015 were collected. Cases completed throax radical radiotherapy whose medical records are accord with the requirements of this study were screened. Patients who had underwent thorax radiotherapy or palliative radiotherapy, did not complete radiotherapy, follow-up period less than 3 months or had no intact medical records were eliminated. Sequential chemoradiotherapy, concurrent chemoradiotherapy, adjuvant or neoadjuvant chemoradiotherapy have no influence on patients selection. Every cases had underwent making thermoplastic membrane, CT scanning with thermoplastic membrane fixing, target region and organs at risk(OARs) contoured by radiologist, physicist making radiotherapy plan according to radiologists' requirements, plan approving and plan confirmation under simulated positioner. Patients were given chemotherapy according to their tumor stage and physical status(PS). The common clinical characteristics and the circumstance that whether or not the radiation induced pneumonia was occurred and its grade(CTCAE V4.0) were collected from the medical records. The left and right lung(deduct GTV) chambers of heart and great vessels were contoured before or after making the radiotherapy plan and the dose-volume parameters were analyzed on the dose-volume histogram(DVH). Heart structures needed to be contoured included left and right atriums, left and right ventricles, coronary artery and its left and right circumflex, anterior descending coronary and pulmonary artery. Structures mentioned above had been analyzed only in DVH without acting as dose limit parameters of organs at risk(OARs). Parameters listed as follows were collected from DVH after completing the radiotherapy plan: 1)The volume and the maximum dose(Dmax), the mean dose(Dmax) of four chambers of the heart; the dose of 1 cubic centimeter tissue received(D1cc), the D2 cc, the D3 cc and the D5 cc of four chambers of the heart, the tissue volume received more than 5Gy(V5), the V10, the V13, the V15, the V20 and the V30 of four chambers of the heart. 2)The volume and the Dmax, the Dmaxof the coronary artery, its left and right circumflex and anterior descending coronary; the V5, the V10, the V13, the V15, the V20 and the V30 of the coronary artery, its left and right circumflex and anterior descending coronary. 3)The volume and the Dmax, the Dmax of the pulmonary artery; the D1 cc, the D2 cc, the D3 cc and the D5 ccof the pulmonary artery; the V40, the V45, the V50, the V55 and the V60 of the pulmonary artery. 4)The Dmax, the Dmax, the V5, the V10, the V20, the V30 and the V40 of the left and right lung. Patients were categorized into sympomatic radiation induced pneumonia group(pneumonia?2 degree) and non-sympomatic radiation induced pneumonia group(pneumonia<2 degree) based on the grade of radiation induced pneumonia. Ordinal regression was adopted to screen dose-volume parameter associated with radiation induced pneumonia. Receiver Operator Characteristic Curve(ROC) was made for factors related to radiation induced pneumonia which had been selected out by ordinal regression analysis to work out their prediction power. Cut-off value of factor whose area under curve of the ROC?50% was screened. Chi-square Test was adopted to compare the incidence of radiation induced pneumonia between two groups that were divided based on cut-off values. Students' Test was used to compare average values of these parameters between sympomatic radiation induced pneumonia group and non- sympomatic radiation induced pneumonia group if Ordinal Regression analysis can not pick out predictable parameter. ROC was made for factors which had significant difference between the two groups and had been picked out by T test. Random select value in all values of every parameter picked out by T Test then compare the incidence of radiation induced pneumonia between the parameter <random value group and the parameter ? random value group. The cut-off value was confirmed if the incidence of sympomatic radiation induced pneumonia was significantly higher in the group whose parameter ? random value than in the group whose parameter < random value while P value was minimal. Kaplan-Meier curve of dose-volume function incidence was mede for the confirmed predictable parameter of radiation induced pneumonia.Results 1. Common characteristics of patients A total of 160 patients entered this study among which the lung squamous cell cancer(SCC) accounted for 23.75%, lung adenocarcinoma accounted for 23.75%, small cell cancer accounted for 11.25%, esophageal SCC accounted for 17.5% and the other pathology types accounted for 23.75%. 36.5% patients had chronic obstructive pulmonary disease(COPD) in the symptomatic radiation induced pneumonia group while 38.0% in the non-symptomatic radiation induced pneumonia group. 2. Association between radiation induced pneumonia and the dose of heart, lung, and the level of serum triglyceride 1)V10,Dmean and V5-V30 of left ventricle, V5-V15 of right ventricle, V5 of left cricumflex coronary artery, V40 of left lung, Dmean and V40 of right lung were significantly higher in symptomatic radiation induced pneumonia group than in the nonsymptomatic radiation induced pneumonia group(P<0.05). 2) All factors mentioned above had prediction ability of symptomatic radiation induced pneumonia in ROC except for V10 of left atrium(area under curve=47.9%) and V40 of left lung(area under curve=48.2%). AUC of the other factors were as follow: In left ventricle, AUC of Dmean was 51.9%,AUC of V5 was 53.9%,AUC of V10 was 54.0%,AUC of V13 was 54.0%,AUC of V15 was 53.4%,AUC of V20 was 50.9%),AUC of V30 was 51.1%. In right ventricle, AUC of V5 was 53.6%,AUC of V10 was 54.7%,AUC of V13 was 53.9%,AUC of V15 was 53.6%. AUC of left cricumflex coronary artery V5 was 50.3%. In right lung, AUC of V40 was 54.1% and AUC of Dmean was 52.7%. 3)When the left ventricle V5<69.86%,V10<58.78%,V13<53.65%,V15<52.60% or V20<46.8%, the incidence of symptomatic radiation induced pneumonia(?2 degree) were 28.4%,27.9%,28.1%,28.6%,29.3% and 29.3% while when the left ventricle V5?69.86%,V10?58.78%,V13?53.65%,V15?52.60% or V20?46.8%, the incidence of symptomatic radiation induced pneumonia were 53.8%,58.3%,61.9%,60.0%,55.0% and 48.1%, respectively(P<0.05). When the left ventricle V10<58.78% or V13<53.65%, the total incidence of radiation induced pneumonia(?1 degree) were 51.5% and 51.8% while when the left ventricle V10?58.78% or V13?53.65%, the incidence of all radiation induced pneumonia were 75.0% and 76.2%,respectively(P<0.05). 4)In the right ventricle, when V5<85.73%, V10<79.21%, V13<77.40% or V15<74.46%, the incidence of symptomatic radiation induced pneumonia were 28.0%,27.9%,29.0% and 29.5%, while the total incidence of radiation induced pneumonia were 50.0%, 50.0%, 50.7%, 51.1%. When the right ventricle V5?85.73%, V10?79.21%, V13?77.40% or V15?74.46%, the incidence of symptomatic radiation induced pneumonia were 53.6%,58.3%,54.5% and 52.4%, while the total incidence of radiation induced pneumonia were 78.6%,83.3%,81.8% and 81.0%, respectively(P<0.05). 5) When the V5 of left cricumflex coronary artery<11.49% and ?11.49%, the incidence of symptomatic radiation induced pneumonia were 11.5% and 88.5%, respectively, P=0.02. The total incidence of all radiation induced pneumonia were 30.6% and 62.1%, respectively, P=0.001. 6)When the V40 of right lung <10.94% and ?10.94%, the incidence of symptomatic radiation induced pneumonia were 27.2% and 43.8%, P=0.04. When the Dmean of right lung <15.02 Gy, the incidence of symptomatic and all radiation induced pneumonia were 27.8% and 50.0%, while when the Dmean of right lung ?15.02 Gy, the incidence of symptomatic and all radiation induced pneumonia were 44.7% and 68.1%, respectively, P=0.04. 7)When the serum triglyceride<3.02 mmol/L and ?3.02 mmol/L, the incidences of symptomatic radiation induced pneumonia were 30.5% and 83.3%, respectively, P=0.007 and the incidences of all radiation induced pneumonia were 53.9%, 83.3%, respectively, P=0.32.Conclusions We got conclusions below according to this retrospective clinical study: 1)The radiation dose of left ventrical has a close relation to symptomatic radiation induced pneumonia. Mean dose of left ventrical < 1062 c Gy, V5<69.86%, V10<58.78%, V13 < 53.65%, V15 < 52.60% and V20 < 46.80%, the incidence of symptomatic radiation induced pneumonia was less than 30%. 2)When the right ventrical V5 < 85.73%, V10 < 79.21%,13 < 77.40%,V15 <74.46%,the incidence of symptomatic radiation induced pneumonia was less than 30%. 3)The incidence of symptomatic radiation induced pneumonia was 11.5% when the V5 of left cricumflex coronary artery was less than 11.49%, while the incidence was 88.5% while the V5 exceeded 11.49%. 4)When the right lung mean dose<1052c Gy or V40<10.94%, the incidence of symptomatic radiation induced pneumonia was less than 30%. In conclusion, the incidence of symptomatic radiation induced pneumonia can be limited in a low level when the left and right ventrical dose and lung dose be limited. 5)The level of the serum triglyceride had an obvious influence on the incidence of symptomatic radiation induced pneumonia. When the level of the serum triglyceride was lower than 3.02 mmol/L, the incidence of symptomatic radiation induced pneumonia decreased significantly. More importance should be attached to the patients whose serum triglyceride is abnormal. In conclusion, through making more specific limitation of the left and right ventrical dose and doing extra adjustment to the normal tissue dose in patients with abnormal serum triglyceride value, the incidence of radiation induced pneumonia can be limited in a low level. |
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