Non-invasive estimation of absorbed ionizing radiation dose in mice using Near-Infrared Spectroscopy (NIRS) and aquaphotomics

Accurate measurement of ionizing radiation exposure, whether therapeutic or accidental, is of utmost importance in various scenarios. This paper presents a study that addresses this critical need by utilizing near-infrared (NIR) spectroscopy and aquaphotomics to estimate radiation dose exposure in mouse models subjected to X-ray irradiation. The analysis of NIR spectra acquired from the mouse abdomen enabled non-invasive estimation of radiation doses ranging from 0.5 to 6.5 Gy, immediately following the irradiation exposure. The findings were consistent with the impact of total body irradiation in mice, as evidenced by measures such as animal survival rate, alterations in body weight observed over a 30-day post-exposure period, and changes in hematocrit levels. The spectroscopic measurements were based on detecting changes in the molecular structure of body water after radiation exposure, utilizing the water spectral pattern as a multidimensional biomarker. While further validation in nonhuman primates is necessary, the findings demonstrate a simple, non-destructive, and rapid method that holds promise for the estimation of radiation exposure across a range of doses, applicable to both clinical applications and catastrophic radiation events. These advancements in radiation dose quantification have significant implications for the timely and precise assessment of radiation exposure in humans. Methods Near infrared spectra acquisition was performed during a period of 30 days, at specific time points: prior to ionizing irradiation (after one week of acclimatization to laboratory conditions), immediately post-irradiation (0 h), and at 6, 12, 24, 48, and 72 hours, followed by subsequent measurements every 5 days until 30 days post-irradiation. At each measurement time, the spectra were collected from mouse abdomen using a portable, hand-held microNIR spectrometer (Viavi Solutions, Santa Rosa, CA, USA) in the spectral range 908 – 1670 nm, with approximately 7 nm resolution step. Five consecutive spectra were acquired for each mouse, at each time when the measurements were performed. The spectral data were analyzed using multivariate analysis methods and preprocessed using extended multiplicative scatter correction.精准测量电离辐射暴露量（无论是治疗性还是事故性）在诸多场景中均具有至关重要的意义。本研究针对这一关键需求，采用近红外光谱（near-infrared spectroscopy, NIR）与水光谱组学（aquaphotomics）技术，对接受X射线辐照的小鼠模型的辐射剂量暴露量进行估算。通过对小鼠腹部采集的近红外光谱进行分析，可在辐照结束后即刻实现0.5~6.5 Gy范围内辐射剂量的无创估算。本研究结果与小鼠全身辐照后的生物学效应相符，该一致性可通过动物存活率、辐照后30天内的体重变化以及血细胞比容水平改变等指标得以验证。本次光谱检测以水光谱模式作为多维生物标志物，捕捉辐照后机体水分子的分子结构变化。尽管仍需在非人灵长类动物中开展进一步验证，但本研究结果证实了一种简便、无损且快速的方法，该方法有望实现不同剂量区间内辐射暴露量的估算，可应用于临床场景与灾难性辐射事件中。辐射剂量定量领域的这一进展，对人类辐射暴露量的及时精准评估具有重要意义。 方法 近红外光谱采集周期为30天，采集时间点设置如下：电离辐照前（适应实验室环境1周后）、辐照后即刻（0小时）、辐照后6、12、24、48、72小时，之后每5天进行一次测量，直至辐照后30天。 每次测量时，采用便携式手持微型近红外光谱仪（Viavi Solutions，美国加利福尼亚州圣罗莎）在908~1670 nm光谱范围内、以约7 nm的分辨率步进采集小鼠腹部的光谱数据。每只小鼠在每次测量时均连续采集5条光谱。 光谱数据采用多元分析方法进行处理，并通过扩展乘法散射校正进行预处理。