Griffiths S E, Pearcey R G, Thorogood J
Int J Radiat Oncol Biol Phys. 1987 Oct;13(10):1583-8. doi: 10.1016/0360-3016(87)90328-2.
A 'blind' study using treatment verification films has been performed on two series of patients to assess the accuracy of placement of complex infradiaphragmatic fields planned to include para-aortic nodes. Sequential verification films (VF) for each field on all patients studied were compared to determine variations in field position relative to the anatomy, especially lymph nodes, and the simulator plan. Nodes included in the plan but partially or completely missed by one or more treatments were identified, as were the error types involved. In series I, 21% of 157 VF showed a nodal miss, and after changes in practice designed to minimize the error types responsible for those, the figure was reduced in series II to 5.5% of 194 VF. In series II a 50% reduction in magnitude of the average systematic lateral shift and rotation of posterior fields is attributed mainly to the discontinuation of the practice of treating posterior fields through the couch. Apart from a prescribed width of less than 9 cm, three quantitative key factors were derived: greater than 6 mm lateral shift, greater than 7 mm field narrowing, 2 degree or more rotation of fields. The correction of these errors if identified on verification films, should eliminate the subsequent occurrence of node misses. The value of routine clinical treatment verification films at the start of treatment to identify and correct systematic errors is emphasized, as is the importance of precise and standardized technical practice.
利用治疗验证片进行了一项“盲法”研究，该研究针对两组患者展开，旨在评估计划包含主动脉旁淋巴结的复杂膈下野放置的准确性。对所有研究患者每个野的序贯验证片（VF）进行比较，以确定野位置相对于解剖结构（尤其是淋巴结）和模拟计划的变化。识别出计划中包含但在一次或多次治疗中部分或完全遗漏的淋巴结以及所涉及的误差类型。在第一组中，157张VF中有21%显示淋巴结遗漏，在采取旨在尽量减少导致这些遗漏的误差类型的操作改进后，在第二组中，194张VF的这一数字降至5.5%。在第二组中，后野平均系统横向移位和旋转幅度降低50%，这主要归因于不再通过治疗床治疗后野的操作。除了规定宽度小于9厘米外，还得出了三个定量关键因素：横向移位大于6毫米、野变窄大于7毫米、野旋转2度或更大。如果在验证片上识别出这些误差并加以纠正，应能消除后续淋巴结遗漏的发生。强调了在治疗开始时进行常规临床治疗验证片以识别和纠正系统误差的价值，以及精确和标准化技术操作的重要性。
