Ekberg L, Holmberg O, Wittgren L, Bjelkengren G, Landberg T
Department of Oncology, Malmoe University Hospital, Sweden.
Radiother Oncol. 1998 Jul;48(1):71-7. doi: 10.1016/s0167-8140(98)00046-2.
The planning target volume in radiotherapy treatment planning takes into account both movements of the clinical target volume (CTV) and set-up deviations.
A group of patients who received radiotherapy for lung cancer were studied. In order to measure the CTV movements due to respiration and other internal organ motions, fluoroscopy was performed for 20 patients. To study the accuracy and reproducibility of patient and beam set-up, 553 electronic portal images from 20 patients were evaluated. Discrepancies between planned and actual field positions were measured and the systematic and random errors were identified. The combined effect of these geometrical variations was evaluated.
The average CTV movement with quiet respiration was about 2.4 mm in the medio-lateral and dorso-ventral directions. Movement in the cranio-caudal direction was on average 3.9 mm with a range of 0-12 mm. The systematic set-up errors were on average 2.0 mm in the transversal plane and 3.0 mm in the cranio-caudal direction. The random errors can be described by their standard deviations of 3.2 and 2.6 mm. In this study, the combined effect of the two parameters (CTV movement and set-up deviations) varied between 7.5 and 10.3 mm in different anatomical directions.
In our daily clinical routine, we use a margin of 11 mm in the transversal plane and 15 mm cranially and caudally, also taking into account other unquantified variations and uncertainties.
放射治疗计划中的计划靶区考虑了临床靶区（CTV）的移动和摆位偏差。
对一组接受肺癌放射治疗的患者进行了研究。为了测量因呼吸和其他内脏器官运动导致的CTV移动，对20例患者进行了透视检查。为了研究患者和射束摆位的准确性和可重复性，评估了20例患者的553张电子门静脉图像。测量计划野位置与实际野位置之间的差异，并确定系统误差和随机误差。评估了这些几何变化的综合影响。
平静呼吸时，CTV在内外侧和背腹侧方向的平均移动约为2.4毫米。头脚方向的移动平均为3.9毫米，范围为0至12毫米。系统摆位误差在横向平面平均为2.0毫米，在头脚方向平均为3.0毫米。随机误差可用其3.2毫米和2.6毫米的标准差来描述。在本研究中，这两个参数（CTV移动和摆位偏差）的综合影响在不同解剖方向上在7.5至10.3毫米之间变化。
在我们的日常临床工作中，我们在横向平面使用11毫米的边界，在头侧和尾侧使用15毫米的边界，同时也考虑了其他未量化的变化和不确定性。
