Almén A, Sandblom V, Båth M, Lundh C
Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, SE-413 45 Gothenburg, Sweden. Department of Radiation Physics, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, SE-413 45 Gothenburg, Sweden.
J Radiol Prot. 2015 Mar;35(1):47-62. doi: 10.1088/0952-4746/35/1/47. Epub 2014 Dec 17.
The optimisation of occupational radiological protection is challenging and a variety of factors have to be considered. Physicians performing image-guided interventions are working in an environment with one of the highest radiation risk levels in healthcare. Appropriate knowledge about the radiation environment is a prerequisite for conducting the optimisation process. Information about the dose rate variation during the interventions could provide valuable input to this process. The overall purpose of this study was to explore the prerequisite and feasibility to measure dose rate in scattered radiation and to assess the usefulness of such data in the optimisation process.Using an active dosimeter system, the dose rate in the unshielded scattered radiation field was measured in a fixed point close to the patient undergoing an image-guided intervention. The measurements were performed with a time resolution of one second and the dose rate data was continuously timed in a data log. In two treatment rooms, data was collected during a 6 month time period, resulting in data from 380 image-guided interventions and vascular treatments in the abdomen, arms and legs. These procedures were categorised into eight types according to the purpose of the treatment and the anatomical region involved.The dose rate varied substantially between treatment types, both regarding the levels and the distribution during the procedure. The maximum dose rate for different types of interventions varied typically between 5 and 100 mSv h(-1), but substantially higher and lower dose rates were also registered. The average dose rate during a complete procedure was however substantially lower and varied typically between 0.05 and 1 mSv h(-1). An analysis of the distribution disclosed that for a large part of the treatment types, the major amount of the total accumulated dose for a procedure was delivered in less than 10% of the exposure time and in less than 1% of the total procedure time.The present study shows that systematic dose rate measurements are feasible. Such measurements can be used to give a general indication of the exposure level to the staff and could serve as a first risk assessment tool when introducing new treatment types or x-ray equipment in the clinic. For example, it could provide an indication for when detailed eye dose measurements are needed. It also gives input to risk management considerations and the development of efficient routines for other radiological protection measures.
职业放射防护的优化具有挑战性，必须考虑多种因素。进行影像引导介入操作的医生所处的工作环境是医疗行业中辐射风险最高的环境之一。了解辐射环境的相关知识是开展优化过程的前提条件。关于介入操作期间剂量率变化的信息可为该过程提供有价值的参考。本研究的总体目的是探讨测量散射辐射剂量率的前提条件和可行性，并评估此类数据在优化过程中的有用性。
使用有源剂量计系统，在接受影像引导介入操作的患者附近的固定点测量无屏蔽散射辐射场中的剂量率。测量以每秒一次的时间分辨率进行，剂量率数据在数据日志中连续计时。在两个治疗室中，在6个月的时间段内收集数据，得到了来自腹部、手臂和腿部的380例影像引导介入操作和血管治疗的数据。这些操作根据治疗目的和涉及的解剖区域分为八类。
不同治疗类型之间的剂量率在水平和操作过程中的分布上都有很大差异。不同类型介入操作的最大剂量率通常在5至100 mSv h⁻¹之间，但也记录到了更高和更低的剂量率。然而，整个操作过程中的平均剂量率要低得多，通常在0.05至1 mSv h⁻¹之间。对分布情况的分析表明，对于大部分治疗类型，一次操作的总累积剂量的主要部分是在不到10%的暴露时间内以及不到总操作时间的1%内给予的。
本研究表明，系统的剂量率测量是可行的。此类测量可用于大致指示工作人员的暴露水平，并可在临床引入新的治疗类型或X射线设备时作为首要的风险评估工具。例如，它可以为何时需要进行详细的眼部剂量测量提供指示。它还为风险管理考虑以及其他放射防护措施的高效流程的制定提供了参考。
