Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York, USA.
J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida, USA.
Med Phys. 2023 Dec;50(12):7390-7399. doi: 10.1002/mp.16696. Epub 2023 Sep 1.
Potential risk associated with low-dose radiation exposures is often expressed using the effective dose (E) quantity. Other risk-related quantities have been proposed as alternatives. The recently introduced risk index (RI) shares similarities with E but expands the metric to incorporate medical imaging-appropriate risks factors including patient-specific size, age, and sex.
The aim of this work is to examine the RI metric for quantifying stochastic radiation risk and demonstrate its applications in nuclear imaging. The advantages in this improved metric may help the field progress toward stratified risk consideration in the course of patient management, improve efforts for procedure optimization, and support an evolution in the science of radiation risk assessment.
In this study we describe, implement, and calculate RI for various diagnostic nuclear imaging scenarios using reference biokinetics published in ICRP Publication 128 for commonly utilized radiopharmaceuticals. All absorbed dose, E and RI calculations were performed using the freely available MIRDcalc nuclear medicine dosimetry software; the organ specific risk parameters used in the software are also benchmarked in this text. The resulting RI and E values are compared and various trends in RI values identified.
E and RI coefficients were calculated for 3016 use cases. Notably RI values vary depending on patient characteristics. Overall, across the population, global trends in RI values can be identified. In general, RI values were 2.15 times higher for females than males, due to higher risk coefficients and activities being distributed in smaller reference masses. The pediatric patients showed higher RIs than adults, as younger patients generally receive higher absorbed doses per administered activity, and are more radiosensitive, and have a longer projected lifespan at risk. A compendium of E and RI values is also provided in table format to serve as a reference for the community.
RI is a rational quantity that could be used for justification, risk communication and protocol optimization in medical imaging. It has some advantages when compared to the long-utilized E value with respect to personalization, since accounts for patient size, age, sex, and natural incidence of cancer risk.
低剂量辐射暴露相关的潜在风险通常使用有效剂量（E）来表示。其他与风险相关的量也被提议作为替代方案。最近引入的风险指数（RI）与 E 有相似之处，但扩展了该指标，纳入了包括患者个体大小、年龄和性别在内的医学成像适当风险因素。
本研究旨在检查 RI 指标在定量随机辐射风险方面的应用，并展示其在核医学成像中的应用。这一改进指标的优势可能有助于该领域在患者管理过程中向分层风险考虑方向发展，改进优化程序的努力，并支持辐射风险评估科学的发展。
在本研究中，我们使用 ICRP 出版物 128 中公布的常用放射性药物的参考生物动力学，描述、实施并计算了各种诊断性核医学成像情况下的 RI。所有吸收剂量、E 和 RI 的计算均使用免费的 MIRDcalc 核医学剂量学软件完成；软件中使用的器官特异性风险参数也在本文中进行了基准测试。比较了 RI 和 E 的值，并确定了 RI 值的各种趋势。
为 3016 种情况计算了 E 和 RI 系数。值得注意的是，RI 值取决于患者特征。总体而言，在人群中，可以确定 RI 值的总体趋势。通常情况下，女性的 RI 值比男性高 2.15 倍，这是由于风险系数较高，活动分布在较小的参考质量中。儿科患者的 RI 值高于成人，因为年轻患者通常每单位活动接受更高的吸收剂量，且更敏感，并且面临更长的风险预期寿命。还以表格形式提供了 E 和 RI 值的汇编，以供社区参考。
RI 是一种合理的量，可以用于医学成像中的正当化、风险沟通和方案优化。与长期使用的 E 值相比，它具有一些优势，因为它考虑了患者的大小、年龄、性别和自然癌症风险发生率。
