van der Geld Ylanga G, Senan Suresh, van Sörnsen de Koste John R, van Tinteren Harm, Slotman Ben J, Underberg René W M, Lagerwaard Frank J
Department of Radiation Oncology, VU University Medical Center, De Boelelaan 1117, Postbox 7057, 1007 MB, Amsterdam, The Netherlands.
Lung Cancer. 2006 Jul;53(1):31-7. doi: 10.1016/j.lungcan.2006.03.013. Epub 2006 May 12.
Fluoroscopy is widely used for evaluating tumor mobility in radiotherapy planning. Lung tumor mobility was scored using virtual fluoroscopy, and this was compared to mobility derived from contoured tumors in all phases of a respiration-correlated (or 4D) CT scan.
4DCT datasets were reviewed and 29 patients were identified in whom tumors were visible on anterior-posterior fluoroscopy views. Mobility in all directions was estimated on fluoroscopy movie loops by four clinicians. These results were compared to mobility measured from contoured tumor volumes in all phases of the same 4DCT. Internal target volumes (ITV) were generated for both approaches.
In eight patients, fluoroscopy did not allow for tumor mobility to be assessed in at least one direction. No significant inter-clinician variation was observed with respect to fluoroscopic assessment of mobility. Clinicians systematically overestimated mobility in all three directions (p<0.05). The mean ITVs derived using fluoroscopy were 52.2% larger than those derived using 4DCT contours, but the individual ITVs were smaller in three patients.
Use of virtual fluoroscopy generally overestimates the mobility of visible lung tumors, and results in irradiation of unnecessarily large target volumes. In contrast, use of 4DCT minimizes the risk of normal tissue toxicity.
荧光透视在放射治疗计划中广泛用于评估肿瘤的移动性。使用虚拟荧光透视对肺部肿瘤移动性进行评分，并将其与在呼吸相关（或4D）CT扫描各期通过勾画肿瘤得出的移动性进行比较。
回顾4DCT数据集，确定29例在前后位荧光透视视图上可见肿瘤的患者。由四名临床医生在荧光透视电影环上评估各个方向的移动性。将这些结果与在同一4DCT各期通过勾画肿瘤体积测得的移动性进行比较。两种方法均生成内部靶区体积（ITV）。
在8例患者中，荧光透视至少在一个方向上无法评估肿瘤移动性。在移动性的荧光透视评估方面，未观察到临床医生之间存在显著差异。临床医生在所有三个方向上均系统性高估了移动性（p<0.05）。使用荧光透视得出的平均ITV比使用4DCT轮廓得出的大52.2%，但有3例患者的个体ITV较小。
使用虚拟荧光透视通常会高估可见肺部肿瘤的移动性，并导致对不必要的大靶区体积进行照射。相比之下，使用4DCT可将正常组织毒性风险降至最低。
