RESUMEN
Objective To compare the dosage characteristics between three-dimensional conformal radiotherapy (3DCRT)plan and simplified inverse dynamic intensity modulated radiotherapy (IMRT)in patients with early-stage breast cancer after breast-conserving surgery.Methods 3DCRT and IMRT treament plans were designed for 14 female patients with early-stage breast cancer after breast-conserving surgery,4 of whom were left breast cancer cases.A dose of 50 Gy in 25 fractions to the whole ipsilateral breast was delivered using 6 MV photons for 3DCRT or IMRT.For 3DCRT plans,tangential field irradiation was adopted.While for IMRT,reverse dynamic intensity modulated technology was done through two pairs of tangential-likely fields, and 10 Gy was boosted to the tumor bed concomitantly in 25 fractions.The conformity index (CI),heterogenei-ty index (HI),dose and volume of organs at risk were evaluated by dose volume histograms (DVH).Results Compared with 3DCRT plans for ipsilateral lung,the high dose volumes were reduced and the low dose volumes were increased in IMRT plans.The same phenomenon was also observed for the heart of the patient with left breast cancer.The crosspoint doses of 3DCRT DVH and IMRT DVH for lung or heart were (25.16 ±9.11) Gy,(28.63 ±10.41 )Gy respectively.There was no difference between the two plans in the V10 of contra-lateral breast [IMRT(4.13 ±5.17)%∶3DCRT(1.99 ±2.43)%,t=2.11,P>0.05],but the D30 and mean of IMRT plan were higher than that of 3DCRT [(2.23 ±1.77)Gy ∶(1.20 ±0.46)Gy,t=2.58,P0.05].While the CI of IMRT plans were improved compared with 3DCRT [(0.75 ±0.07)∶(0.62 ±0.09),t =5.68,P<0.000 1]. Conclusion Compared with 3DCRT plan in patients with early-stage breast cancer after breast-conserving surgery,the main advantages of four fields simplified inverse dynamic IMRT are concomitant tumor boosting, decreasing the high dose volumes of ipsilateral lung,and improving the CI of planning target volume at the same time,but the HI is not improved.The IMRT plan is a simple,rational and feasible design scheme.
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Bladder cancer is a common malignant tumor in urinary system. The life quality of patients reduces obviously after radical resection of bladder. Comprehensive treatment including radiotherapy and chem-otherapy after bladder preservation surgery plays an important role for the prevention of postoperative recur-rence,preservation the function of bladder,and improving the life quality of patients. Image-guided radiothera-py can reduce the setup error and inner boundary caused by the movement of organs,and can alleviate the side reaction of radiation,and it also can provide basis of expanding boundary of planning target volume for the blad-der cancer patients.
RESUMEN
Obiective To study the regularity of three-dimensional displacement in respiration of lung cancer. Methods Af-ter CT scanning, the CT images were transferred into target planning system (TPS) to obtain three-dimensional reconstruc-tion images. Then target drawing and noting of target position, tumor volume, lung function, patient gender, age and weight were performed. The images during the course of inspiration and expiration in simulator were scanned and transferred into TPS by DICOM RT port. At last, the three-dimensional displacement curve of the interested points(X,Y and Z axis) could be obtained. Results The three-dimensional real time displacement curve of lung cancer interested points could be estab-fished by the way of collecting simulator images and drawing interested points. The maximum displacement range of the interested points were 4.2mm in Z-axis(head-foot direction), 3.8ram in X-axis(left-right direction), 2.9ram in Y-axis(ante-rior-posterior direction). Conclusion The three--dimensional real time displacement curve of lung cancer at any point of the target can be established by collecting the dynamic images in simulator and reconstructing of the corresponding images in target planning system through the DICOM RT.