ABSTRACT
Objective@#To compare the dosimetric differences in forward intensity-modulated radiotherapy using field-in-field (FIF-F-IMRT) and inverse intensity-modulated radiotherapy (I-IMRT) for the left-sided breast cancer.@*Methods@#A total of 18 patients with left-sided breast cancer undergoing breast-conserving surgery in Shanxi Provincial People's Hospital from January to July 2015 were enrolled. For each patient, two treatment plans were designed. The plans were compared by means of target dose distribution and dose for organ at risk.@*Results@#The two methods met the requirements of the prescribed doses. There were no differences for maximal dose (Dmax), mean dose (Dmean), and 100%, 105%, 110% prescription dose percent volume (V100, V105, V110) of the target (all P > 0.05). The percentage volume of heart receiving 5 Gy (V5), 20 Gy (V20), 30 Gy (V30), Dmean of heart of FIF-F-IMRT [(11±4)%, (7±4)%, (8±3)%, (15±3) Gy] were lower than those of I-IMRT [(42±8)%, (14±10)%, (14±4)%, (18±7) Gy] (t values were 29.457, 5.542, 5.064, 4.165, all P = 0.000). V5 of left-sided lung of FIF-F-IMRT [(26±6)%] was lower than that of I-IMRT [(47±12)%] (t = 6.708, P = 0.000), but there was no significant difference between the two groups in V20, V30, V40, Dmean of left-sided lung (all P≥0.05). V5 of right-sided lung and right-sided breast, Dmean of right-sided lung of FIF-F-IMRT [(7±4)%, (26±5)%, (60±19) Gy] were lower than those of I-IMRT [(31±9)%, (48±11)%, (489±67) Gy] (t values were 12.304, 6.708, 42.489, all P = 0.000). The number of the monitor units and spending time of FIF-F-IMRT were lower than those of I-IMRT (t values were 12.214 and 29.899, both P = 0.000).@*Conclusion@#FIF-F-IMRT has a good dose distribution in the target volume, and could reduce the dose for organ at risk, especially reduce the unnecessary low dose irradiation, and consume less planning time and equipment consumption.
ABSTRACT
Objective To explore the relative factors of radiation pneumonia(RP) in patients with lung cancer after radiotherapy,and find predictors of reasonable.Methods 98 cases received radical radiotherapy of non-small cell lung cancer patients were included,prescription dose of 60-68 Gy,clinical symptoms,chest X-ray,HRCT were used to detect RP.The clinical factors and treatment parameters were collected.Analysis of univariate and multivariate were used for chnical data and treatment planning indicators,assessment of RP related factors.Results 26 cases (26.53 ％) were RP in 2 above (≥2).The univariate anaiysis revealed that many parameteers (chronic obstructive pulmonary disease,whether chemotherapy,tumor volume,V20,V25,V30) were significantly associated with RP (x2 =12.253,x2 =8.802,t =3.758,t =3.432,t =3.210,t =3.190,P ＜ 0.05).Multivariate analysis revealed that COPD and V20＞25 ％,V30＞18 ％ were associated with RP (x2 =4.17,24.18,3.56,P =0.045,0.041,0.000).Conclusion Lung V20,V30,patients with chronic lung disease are the independence of the influencing factors of RP.In patients with chronic obstructive pulmonary disease the dose of normal tissue should be strictly controled,V20 ≤ 25 ％,V30 ≤ 18 ％.