Supplementary Material for: The applicability of scoring calyculin A-induced premature chromosome condensation (PCC) objects for dose assessment including for radiotherapy patients

As an extension to a previous study, a linear calibration curve covering doses from 0 to 10 Gy was constructed and evaluated in the present study using calyculin A-induced premature chromosome condensation (PCC) by scoring excess PCC objects. The main aim of this study was to assess the applicability of this PCC assay for doses below 2 Gy that are critical for triage categorisation. Two separate blind tests involving a total of 6 doses were carried out. 4 out of 6 dose estimates were within the 95% confidence limits (95%CL) with the other 2 just outside. In addition, blood samples from five cancer patients undergoing external beam radiotherapy (RT) were also analysed and the results showed whole-body dose estimates statistically comparable to the dicentric chromosome assay (DCA) results. This is the first time that calyculin A-induced PCC was used to analyse clinical samples by scoring excess objects. Although dose estimates for the pre-RT patient samples were found to be significantly higher than the mean value for the healthy donors and were also significantly higher than those obtained using DCA, all these pre-treatment patients fell into the same category as those who may have received a low dose (< 1 Gy) and do not require immediate medical care during emergency triage. Additionally, for radiological accidents with unknown exposure scenario, PCC objects and rings can be scored in parallel for the assessment of both low and high dose exposures.

In conclusion, scoring excess objects using calyculin A-induced PCC is confirmed to be another potential biodosimetry tool in radiological emergency particularly in mass casualty scenarios even though the data need to be interpreted with caution when cancer patients are among the casualties.

本研究作为既往研究的延伸，通过计数过量PCC物体，采用纺锤菌素A（calyculin A）诱导的早熟染色体凝集（PCC，premature chromosome condensation）体系，构建并评估了覆盖0~10 Gy剂量范围的线性校准曲线。本研究的核心目标为评估该PCC检测方法在低于2 Gy剂量区间的适用性——该剂量区间是放射伤员分诊分级的关键区间。本研究开展了两组独立盲法试验，共涵盖6种剂量梯度，其中4个剂量估算值落在95%置信限（95%CL）范围内，剩余2个则恰好处于置信限之外。此外，本研究还对5名接受外照射放疗（RT，external beam radiotherapy）的癌症患者的血液样本进行了分析，结果显示该方法得到的全身剂量估算值与双着丝粒染色体分析（DCA，dicentric chromosome assay）结果无统计学差异。这是首次采用纺锤菌素A诱导的PCC技术，通过计数过量物体分析临床样本。尽管放疗前患者样本的剂量估算值显著高于健康供体的平均水平，同时也显著高于DCA方法得到的结果，但所有放疗前患者均被划归至“接受低剂量（<1 Gy）照射、无需紧急医疗干预”的应急分诊类别中。
此外，对于暴露场景不明的放射事故，可同时计数PCC物体与环状染色体，以同步评估低剂量与高剂量照射情况。
综上，尽管当伤亡人群中包含癌症患者时，需谨慎解读相关数据，但本研究证实，采用纺锤菌素A诱导的PCC技术计数过量物体，可作为放射应急场景（尤其是大规模伤亡场景）下的潜在生物剂量计工具之一。