CAJ | 학술논문

目的：研究4DCT 与4DCBCT 对三维运动模体的成像和配准精度。方法对CIRS008A模体进行4DCT和4DCBCT扫描。用直径1、2 cm小球模拟不同大小肿瘤，设置小球在三维方向作正弦运动（上下、前后和左右方向振幅分别为±1?0、±0?4、±0?2 cm），运动周期为4 s。勾画图像中的10个时相靶区、IGTV、MIP 及平均密度投影（ MeanIP ）的靶区并测量体积。对4DCT 与4DCBCT图像靶体积与小球静止体积VS 及运动体积VD 相比较；刚性配准后分析4DCT与4DCBCT图像靶区的匹配度（ MI）。结果图像中各时相的靶体积均＞VS。小体积小球的4DCT与4DCBCT图像各时相体积均值相对于VS 的变化（35?03％和32?62％）大于大体积小球22?66％和17％）。 ITV和MIP靶区体积略＞VD ，MeanIP靶区体积＜VD。小体积小球各时相靶区的平均MI （66?76％）小于大体积小球MI （82?21％）；同时IGTV、MIP、MeanIP的MI （77?39％、75?90％、74?47％）也小于大体积小球的IGTV、MIP、MeanIP （90?29％、89?28％、82?74％）。结论在肿瘤体积较小、运动幅度较大的情况下，谨慎使用4DCT与4DCBCT进行相互间配准比较。
목적：연구4DCT 여4DCBCT 대삼유운동모체적성상화배준정도。방법대CIRS008A모체진행4DCT화4DCBCT소묘。용직경1、2 cm소구모의불동대소종류，설치소구재삼유방향작정현운동（상하、전후화좌우방향진폭분별위±1?0、±0?4、±0?2 cm），운동주기위4 s。구화도상중적10개시상파구、IGTV、MIP 급평균밀도투영（ MeanIP ）적파구병측량체적。대4DCT 여4DCBCT도상파체적여소구정지체적VS 급운동체적VD 상비교；강성배준후분석4DCT여4DCBCT도상파구적필배도（ MI）。결과도상중각시상적파체적균＞VS。소체적소구적4DCT여4DCBCT도상각시상체적균치상대우VS 적변화（35?03％화32?62％）대우대체적소구22?66％화17％）。 ITV화MIP파구체적략＞VD ，MeanIP파구체적＜VD。소체적소구각시상파구적평균MI （66?76％）소우대체적소구MI （82?21％）；동시IGTV、MIP、MeanIP적MI （77?39％、75?90％、74?47％）야소우대체적소구적IGTV、MIP、MeanIP （90?29％、89?28％、82?74％）。결론재종류체적교소、운동폭도교대적정황하，근신사용4DCT여4DCBCT진행상호간배준비교。
Objective To evaluate the image quality and registration accuracy of a three?dimensional ( 3D ) dynamic phantom in four?dimensional computed tomography ( 4DCT ) and four?dimensional cone?beam computed tomography ( 4DCBCT) . Methods The Computerized Imaging Reference Systems Dynamic Thorax Phantom Model 008A was scanned to get 4DCT and 4DCBCT images. Two balls with different diameters ( ?= 1 cm and ?= 2 cm) were used to simulate tumors with different sizes. The motion mode of the balls was 3D sinusoidal motion at 0?25 Hz ( the amplitudes along the x, y, and z axes were ±1?0 cm, ±0?4 cm, and ±0?2 cm, respectively). Gross target volumes (GTVs) from 10?phase bins, internal gross target volumes (IGTV), and target volumes on maximum intensity projection (MIP) and mean intensity projection (MeanIP) images were contoured and calculated. Target volumes on 4DCT or 4DCBCT images were compared with the static and dynamic volumes of the balls ( VS and VD ) . The matching index ( MI) of target volumes between the 4DCT and 4DCBCT images was analyzed after rigid image registration. Results The GTV in each phase of the image was larger than VS . The difference between the average GTV derived from 10 phases of 4DCT or 4DCBCT images and Vs of the small ball was larger than that of the large ball ( 35?03% vs. 22?66%;32?62% vs. 17?00%) . All the IGTVs and target volumes on MIP images were slightly larger than VD , but target volumes on MeanIP images were smaller than VD . The average MI of 10?phase bins of the small ball was smaller than that of the large ball ( 66?76% vs. 82?21%) . Moreover, MIs of IGTV,MIP, and MeanIP of the small ball were also smaller than those of the large ball ( 77?39% vs. 90?29%;75?90% vs. 89?28%;74?47% vs. 82?74%) . Conclusions In the case of a relatively small tumor volume and a relatively large motion amplitude, 4DCT and 4DCBCT should be used with caution for comparison of image registration.