| Objective:To investigate the influence of the level of the chest wall Irradiation field tangent circles on dose to the lung of breast cancer patients post-mastectomy treated with three-dimensional conformal radiotherapy (3D-CRT).Method:A retrospective analysis of108breast cancer patients who recieved adjuvant radiotherapy after mastectomy, between September2009and September2011in our hospital, the radation target included the ipsilateral chest wall and the supraclavicular upper and lower areas.108patients were divided into two groups:the chest wall tangent wild upper bound located in the former rib before inferior, while the control group was located in the2nd rib level before inferior. There were56patients in the experimental group, and52patients in the control group. Using the Ucletron Treatment Planning systems (Treatment Planning System TPS) to design radiotherapy plan. All patients recieved three dimensional conformal radiotherapy (3D-CRT). The two groups were compared with DVH parameters, such as ipsilateral lung and total lungs’V5,V10,V20,V30, maximum lung depth (MLD), the largest volune, the smallest volume and the average volume of the lung, analyzing the correlation of DVH parameters and the dose to the lung, to understand the different set of upper bound of chest wall irradiation field by the influence of the lung volume, and to analyze the designed field on the amount of the lung.Results:The percentage of ipsilateral lung/total lungs as5Gy, lOGy,20Gy,30Gy volume in the experimental group are lower than in the control group. In ipsilateral lung, V5were38.78%±3.48%and40.76%±5.94%(P=0.005), V10were31.48%±3.20%and33.50%±4.80%(P=0.046), V20were27.53%＋3.14%and30.09%＋4.74%(P=0.048), V30were24.44%＋3.19%and27.30%±4.69%(P=0.035) respectively. In the double lung, V5were19.55%±2.78%and21.99%±3.80%(P=0.022), V10were16.53%±1.98%and18.82%±2.86%(P=0.042), V20were13.58%±2.07%and16.99%±2.88%(P=0.037), V30were11.28%=±1.82%and14.87%±2.56%(P=0.030) respectively. To Compare the two groups in the right breast cancer patients with ipsilateral lung, V5were39.02%±2.25%and39.35%±4.53%(P=0.038), V10were32.81%±1.84%and32.82±3.91%(P=0.0200), V20were29.05±1.97%and29.87±3.96%(P=0.039), V30were26.00±2.10%and27.50±3.97%(P=0.020); at the total lungs, V5were17.64±1.37%and19.58±0.91%(P=0.026), V10were15.73±1.26%and17.54%±0.90%(P=0.030), V20were12.64%±1.41%and15.62%±0.97%(P=0.066), V30were10.44%±1.16%and13.66%±0.92%(P=0.065) respect-tively. The maximum lung depth, the largest amount and the average amount of the lung in the two groups were1.57±0.40cm and1.89±0.45cm (P=0.674),4578.27±1880.26cGy and5225.06±988.36cGy (P=0.000),1277.40±594.63cGy and1515.52±362.59cGy (P=0.002) respectively. Lesions located in the left, the MLD in the two groups are1.62±0.36cm and1.98±0.24cm (P=0.035). Lesions was located in the left, the averages of MLD are1.52±0.43cm and1.81±0.58cm (P=0.017). The MLD of all patients was no more than3centimeters.Concelusion:The research shows that the level of chest wall irradiation field has influence to the lung of patient receiving3D-CRT after mastectomy. The level of chest wall irradiation field has influence to the lung of right or left breast cancer patients. |
