Lessons on harmonization of scoring criteria for dicentric chromosome assay in South Korea

Networking with other biodosimetry laboratories is necessary to assess the radiation exposure of many individuals in large-scale radiological accidents. The Korea biodosimetry network, K-BioDos, prepared harmonized scoring guidelines for dicentric chromosome assay to obtain homogeneous results within the network and investigated the efficiency of the guidelines. Three laboratories in K-BioDos harmonized the scoring guidelines for dicentric chromosome assay. The results of scoring dicentric chromosomes using the harmonized scoring guidelines were compared with the laboratories’ results using their own methods. Feedback was collected from the scorers following the three intercomparison exercises in 3 consecutive years. K-BioDos members showed comparable capacity to score dicentrics in the three exercises. However, the results of the K-BioDos guidelines showed no significant improvement over those of the scorers’ own methods. According to the scorers, our harmonized guidelines led to more rejected metaphases and ultimately decreased the number of scorable metaphases compared with their own methods. Moreover, the scoring time was sometimes longer with the K-BioDos protocol because some scorers were not yet familiar with the guidelines, though most scorers reported that the time decreased or was unchanged. These challenges may cause low adherence to the guidelines. Most scorers expressed willingness to use the guidelines to select scorable metaphases or identify dicentrics for other biodosimetry works, whereas one did not want to use it due to the difference from their calibration curves. We identified potential resistance to following the harmonized guidelines and received requests for more detailed methods. Our findings suggest that the harmonized criteria should be continually updated, and education and training should be provided for all scorers. These changes could allow members within the biodosimetry network to successfully collaborate and support each other in large-scale radiological accidents.

在大规模辐射事故中，为评估大量受照个体的辐射暴露情况，与其他生物剂量测定（biodosimetry）实验室建立合作网络实属必要。韩国生物剂量测定网络（K-BioDos）针对双着丝粒染色体分析（dicentric chromosome assay）制定了统一评分指南，以期在网络内部获得均一的实验结果，并对该指南的应用效能进行了评估。K-BioDos旗下三家实验室对双着丝粒染色体分析的评分指南进行了统一校准。随后，将采用统一评分指南得到的双着丝粒染色体评分结果，与各实验室使用自身常规方法得到的结果进行对比。在连续三年完成三次实验室间比对试验后，研究团队收集了评分人员的反馈信息。K-BioDos的参与成员在三次比对试验中展现出了相近的双着丝粒评分能力。然而，采用K-BioDos统一指南得到的评分结果，并未显著优于各实验室使用自身方法得到的结果。据评分人员反馈，相较于各自常规方法，采用本研究制定的统一指南会导致更多中期分裂相（metaphase）被剔除，最终减少了可用于评分的中期分裂相数量。此外，由于部分评分人员尚未熟悉该指南，使用K-BioDos统一方案的评分耗时有时会更长；不过多数评分人员表示，评分耗时有所缩短或保持不变。上述问题可能会降低成员对统一指南的依从性。多数评分人员表示愿意在其他生物剂量测定工作中，使用该指南筛选可评分中期分裂相或识别双着丝粒染色体；但有一名评分人员因该指南与自身校准曲线（calibration curves）存在差异，不愿采用该指南。本研究发现，部分成员对遵循统一指南存在潜在抵触心理，同时收到了关于完善详细操作步骤的诉求。本研究结果提示，应持续优化统一评分标准，并为全体评分人员开展系统性教育培训。上述优化举措将有助于生物剂量测定网络的成员在大规模辐射事故中开展高效协作并互相支援。