低剂量4DCT扫描在肺内孤立性肿瘤模拟定位与靶区构建中的应用价值

Application value of low-dose 4DCT scanning in simulation and target delineation for solitary pulmonary tumors

目的探讨低剂量4DCT扫描在肺内孤立性肿瘤模拟定位和靶区构建中的可行性。方法23例肺内孤立性肿瘤序贯完成常规条件(CON)、低管电压(LV)、低管电流(LA)、低管电压+低管电流(LVA)条件下4DCT扫描模拟定位,基于各序列图像分别进行靶区构建与配准,比较不同扫描条件下肿瘤内运动靶区(IGTV)体积、位置、肿瘤位移及辐射剂量的差异。结果靶区IGTV_(CON)、IGTV_(V)、IGTV_(A)分别为(12.26±12.30)、(12.21±12.16)、(11.87±11.70)cm^(3)(P=0.337),IGTVVA为(11.34±11.07)cm^(3)小于IGTVCON(P=0.005)。IGTV_(CON)、IGTV_(V)、IGTV_(A)、IGTV_(VA)中心位置均相近(3D方向P=0.491、0.360、0.136)。戴斯相似系数DSC_(VA)小于DSC_(V)、DSC_(A)(P=0.004、0.030)。4种扫描条件下测量的肿瘤位移在左右、前后方向上均相近(P=0.470、0.108),在头脚方向上,LVA条件下测量的肿瘤位移小于CON条件(P=0.015)。4种扫描条件下的辐射剂量分别为(397.0±140.3)、(175.0±61.8)、(264.8±95.3)、(116.8±41.2)mGy·cm(P<0.001)。结论肺内孤立性肿瘤4DCT模拟定位时LV或LA对IGTV体积和位置、肿瘤位移无明显影响,但可降低患者辐射剂量;因此其在模拟定位和靶区构建中具有可行性。

Objective To explore the feasibility of low-dose 4DCT scanning in simulation and target delineation for solitary pulmonary tumors(SPTs).Methods 23 patients with SPTs received 4DCT scanning simulation with the conventional scanning(CON),low voltage(LV),low current(LA)and low voltage combined with low current(LVA)in sequence.Based on the 4DCT images derived from the four sets of scanning parameters,the internal gross tumor volume(IGTV_(CON),IGTV_(V),IGTV_(A),IGTV_(VA))of SPTs were delineated and matched.Taking IGTV_(CON) as reference,the tumor displacement and the centroid position of IGTV_(V),IGTV_(A) and IGTV_(VA) were compared with IGTV_(CON).The radiation doses under different scanning parameters were compared.Results The volumes of IGTV_(CON),IGTV_(V) and IGTV_(A) were(12.26±12.30)cm^(3),(12.21±12.16)cm^(3) and(11.87±11.70)cm^(3),respectively(P=0.337).IGTVVA was(11.34±11.07)cm^(3),significantly smaller than IGTV_(CON)(P=0.005).There was no significant difference in the centroid positions of IGTV_(CON),IGTV_(V),IGTV_(A) and IGTV_(VA) in three directions(P=0.491,0.360,0.136).The Dice′s similarity coefficient(DSCVA)was significantly lower than DSC_(V) and DSC_(A)(P=0.004,0.030).The tumor displacement measured by the four sets of 4DCT images was similar in the LR direction(P=0.470),and also in the AP direction(P=0.108).For the displacement in the SI direction,LVA scanning was smaller than CON(P=0.015).The radiation doses under four different scanning conditions were(397.0±140.3)mGy·cm,(175.0±61.8)mGy·cm,(264.8±95.3)mGy·cm and(116.8±41.2)mGy·cm,respectively(P<0.001).Conclusions LV or LA scanning exert no significant effect on the volume,centroid position of IGTV and the tumor displacement in 4DCT simulation for SPTs.The radiation dose that patients receive under LV and LV scanning is lower than that of CON.Consequently,LV or LA scanning is feasible in 4DCT simulation and target delineation for SPTs.