宫颈癌图像引导下调强放射治疗靶区及危及器官变化研究

Study on the Changes of Volume and Spatial Location in Target and Organ at Risk for Cervical Cancer during Image-guided IMRT

[目的]通过量化的方法研究宫颈癌图像引导下调强放射治疗（IGRT）中靶区与危及器官体积及空间变化。[方法]选取10例调强放射治疗的宫颈癌患者,放疗前用锥形束CT（CBCT）扫描采集连续3d的CBCT图像,后每周1次CBCT图像,共采集第1-3d及第2-6周8组图像（Plan1-Plan8）,分析靶区及危及器官的体积变化,同时使用体积差异法和DICE相似度法评价空间位置的变化。[结果]肿瘤原发病灶（GTV-T）治疗前体积（Plan1）59.26±24.83cm^3（36.30-82.22cm^3）,治疗后体积（Plan8）16.40±3.71cm^3（12.96-19.83cm^3）,治疗前Plan1与治疗中Plan3-Plan8比较,差异均有显著性（P〈0.05）。体积差异法评价变化范围：GTV-T为4.57%-44.05%,GTV-N（盆腔转移淋巴结）为-3.99%-14.24%,CTV为-4.36-10.03%。使用DICE值法评价靶区、危及器官均值及变化范围分别为：GTV-T 0.71±0.13（0.34-0.92）,GTV-N 0.56±0.21（0.46-0.73）,CTV 0.85±0.03（0.82-0.85）;膀胱0.59±0.16（0.52-0.88）,直肠0.67±0.21（0.59-0.87）,小肠0.68±0.11（0.54-0.88）。[结论 ]放射治疗后宫颈原发肿瘤相对于治疗前明显缩小,空间位置及危及器官均有明显的变化。放射治疗中采用量化标准评估宫颈感兴趣范围的变化,可及时修改放射治疗计划,保证肿瘤照射剂量和减少危及器官的受照剂量。

[Purpose] To investigate the changes of volume and spatial location in target and organ at risk using quantifiable valuation method during image-guided IMRT（IGRT） for cervical cancer.[Methods] Ten cases with cervical cancer were treated by IGRT. Cone-beam CT was scanned at first three days and then one time weekly during treatment（a total of 8 groups of image ：Plan1-Plan8）. The volume change of target and organ at risk were analyzed,and changes of spatial location were evaluated by volume difference and DICE similarity methods. [Results] The volume of GTV-T（primary tumor lesions） in Plan1 was 59.26±24.83cm^3（range 36.30-82.22cm^3） and in Plan8 was 16.40±3.71cm^3（range 12.96-19.83cm^3）. There was significant difference of GTV-T between Plan1 and Plan3- Plan8（all P 0.05）.The volume difference method showed that the volume change of GTV-T,CTV and GTV-N was 4.57% -44.05%,-4.36% -10.03% and-3.99% -14.24%respectively. The DICE parameter method showed that change of target and organ at risk showed that the GTV-T was 0.71±0.13（0.34-0.92）,GTV-N was 0.56±0.21（0.46-0.73） CTV was 0.85±0.03（0.82-0.85）,bladder was 0.59±0.16（0.52- 0.88）,rectum was 0.67±0.21（0.59-0.87）and intestine was 0.68±0.11（0.54-0.88）.[Conclusions] The primary tumor volume reduced obviously of patients with cervical cancer after IGRT,and there is a significant change of space position and organ at risk. To evaluate the changes of interested area of cervix by quantifiable method,can timely modify radiotherapy planning to ensure adequate target dose and avoid endanger organ dose.