| Nrecent years, with the fast push of a variety of imaging devices and video mode, cervical cancer brachytherapy has entered a three-dimensional era. At present, because of the economic or convenience, and other reasons, the target contour is described mainly based on CT images. While the CT images does not have high resolution in the soft tissue or small density region, which leading to the definition of the target area for clinicians to have differences. It can make the tumor area clear by overlapping the MRI image with high resolution of soft tissue and CT image information in a pair of images. Thereby that way can reduces the difference of the target area defined by different doctors. CT-MRI fusion method is adopted in this thesis to outline the target region of cervical cancer in three-dimensional brachytherapy by image registration and fusion technology. Then we compaired the volume of target difined on the base of MRI and CT and the dose of target and organs at risk. The aim is to explore the feasibility of applying CT-MRI fusion in the basic level hospitals, and to provide the data for the more fusion technology.20 cases of cervical cancer patients were seclected. Clinical stage:1 case of ?b 1 stage and?b 2 stage,2 cases of ?a stage,the rest of them were ?b stage. The pathological types were: 4 cases of cervical carcinoma, 16 cases of squamous cell carcinoma. Median age was 54 years(34~66 years). Two sets of target areas and two radiotherapy plans were completed were completed in the same patient. The target area was outlined in the CT-MRI fusion image and the 3D brachytherapy plan was established(Fusion group). Then, the target area is outlined in the CT image and 3D brachytherapy plan was established(CT group).The volume of HR-CTV,dose of target and organs at risk of different groups was compared. The results showed: The volume of HR-CTV in Fusion group was 68.67cm3,while in the CT group was 79.25 cm3,which was 13.35% less than Fusion group. The difference was statistically significant(t=2.265, P=0.029).The mean value of D2CC?D1CC?D0.1CC of bladder in the Fusion group and CT group were 468.57 c Gy v.s 483.47 c Gy( t=2.205, P=0.034),489.42 c Gy v.s 524.29 c Gy(t=2.205,P=0.034),568.24 c Gy v.s 581.16 c Gy(t=2.453,P=0.021). The mean value of D2CC?D1CC?D0.1CC of rectum in the Fusion group and CT group were 349.97 c Gy v.s 382.52 c Gy(t=2.839,P=0.010)?443.91 c Gy v.s 461.29 c Gy(t=2.37,P=0.031)?507.62 c Gy v.s 541.58 c Gy(t=3.082,P=0.007).And The mean value of D2CC?D1CC?D0.1CC of rectum in the Fusion group and CT group were 405.48 c Gy v.s 446.98 c Gy(t=3.112,P=0.005)?438.24 c Gy v.s 468.43 c Gy(t=2.864,P=0.008)?537.75 c Gy V.S 562.69 c Gy(t=2.582,P=0.016). There were no significant differences between the target dose of two groups. Conclusion: The target volume of cervical cancer on the base of fusion images were smaller than on the CT images, and CT-MRI fusion image could reduce the dose received by organs at risk compaired to CT images. |
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