Sgouros George, Howell Roger W, Bolch Wesley E, Fisher Darrell R
Department of Radiology and Radiological Science, School of Medicine, Johns Hopkins University, Baltimore, Maryland 21231, USA.
J Nucl Med. 2009 Mar;50(3):485-7. doi: 10.2967/jnumed.108.057398.
The fundamental physical quantity for relating all biologic effects to radiation exposure is the absorbed dose, the energy imparted per unit mass of tissue. Absorbed dose is expressed in units of joules per kilogram (J/kg) and is given the special name gray (Gy). Exposure to ionizing radiation may cause both deterministic and stochastic biologic effects. To account for the relative effect per unit absorbed dose that has been observed for different types of radiation, the International Commission on Radiological Protection (ICRP) has established radiation weighting factors for stochastic effects. The product of absorbed dose in Gy and the radiation weighting factor is defined as the equivalent dose. Equivalent dose values are designated by a special named unit, the sievert (Sv). Unlike the situation for stochastic effects, no well-defined formalism and associated special named quantities have been widely adopted for deterministic effects. The therapeutic application of radionuclides and, specifically, alpha-particle emitters in nuclear medicine has brought to the forefront the need for a well-defined dosimetry formalism applicable to deterministic effects that is accompanied by corresponding special named quantities. This commentary reviews recent proposals related to this issue and concludes with a recommendation to establish a new named quantity.
将所有生物效应与辐射暴露相关联的基本物理量是吸收剂量，即单位质量组织所吸收的能量。吸收剂量的单位是焦耳每千克（J/kg），并赋予了专门名称戈瑞（Gy）。暴露于电离辐射可能会导致确定性和随机性生物效应。为了考虑不同类型辐射每单位吸收剂量的相对效应，国际放射防护委员会（ICRP）已为随机性效应确定了辐射权重因子。以戈瑞为单位的吸收剂量与辐射权重因子的乘积定义为当量剂量。当量剂量值由一个专门的命名单位希沃特（Sv）表示。与随机性效应的情况不同，对于确定性效应，尚未广泛采用明确的形式体系和相关的专门命名量。放射性核素，特别是α粒子发射体在核医学中的治疗应用，凸显了对适用于确定性效应的明确剂量学形式体系以及相应专门命名量的需求。本评论回顾了与该问题相关的近期提议，并以建议设立一个新的命名量作为结论。
