Title: Measuring foetal dose from tomotherapy treatments Show Chinese title

Title: 从断层治疗中测量胎儿剂量

Abstract: Introduction: Treating pregnant women in the radiotherapy clinic is a rare occurrence. When it does occur, it is vital that the dose received by the developing embryo or foetus is understood as fully as possible. This study presents the first investigation of foetal doses delivered during helical tomotherapy treatments. Materials & Methods: Six treatment plans were delivered to an anthropomorphic phantom using a tomotherapy machine. These included treatments of the brain, unilateral and bilateral head-and-neck, chest wall, and upper lung. Measurements of foetal dose were made with an ionisation chamber positioned at various locations longitudinally within the phantom to simulate a variety of patient anatomies. Results: All measurements were below the established limit of 100 mGy for a high risk of damage during the first trimester. The largest dose encountered was 75 mGy (0.125% of prescription dose). The majority of treatments with measurement positions less than 30 cm fell into the range of uncertain risk (50 - 100 mGy). All treatments with measurement positions beyond 30 cm fell into the low risk category (< 50 mGy). Conclusions: For the cases in this study, tomotherapy resulted in foetal doses that are at least on par with, if not significantly lower than, similar 3D conformal or intensity-modulated treatments delivered with other devices. Recommendations were also provided for estimating foetal doses from tomotherapy plans. Show Chinese abstract

Abstract: 介绍：在放射治疗诊所中治疗孕妇是非常罕见的。 当这种情况发生时，了解发育中的胚胎或胎儿所接受的剂量尽可能全面是非常重要的。 本研究首次调查了螺旋调强放疗治疗过程中胎儿接受的剂量。 材料与方法：使用调强放疗机，将六个治疗计划施用于人体形态幻象。 这些包括大脑、单侧和双侧头颈部、胸壁和上肺部的治疗。 通过在幻象内不同纵向位置放置电离室来测量胎儿剂量，以模拟各种患者解剖结构。 结果：所有测量值均低于第一孕期高损伤风险的100 mGy既定限值。 遇到的最大剂量为75 mGy（处方剂量的0.125%）。 大多数测量位置小于30厘米的治疗处于不确定风险范围（50-100 mGy）。 所有测量位置超过30厘米的治疗都属于低风险类别（<50 mGy）。 结论：对于本研究中的病例，调强放疗产生的胎儿剂量至少与类似的三维适形或强度调制治疗相当，如果不是显著低于其他设备提供的类似治疗的话。 还提供了从调强放疗计划估计胎儿剂量的建议。