Key Data for Ionizing-Radiation Dosimetry: Measurement Standards and Applications
Key Data for Ionizing-Radiation Dosimetry: Measurement Standards and Applications
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电离辐射剂量测定的关键数据：测量标准和应用
DOI：
10.1093/jicru_ndw043
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
F. Salvat
中科院分区：
文献类型：
--
作者：
S. Seltzer;J. Fernández;P. Andreo;P. Bergstrom;D. Burns;I. K. Bronić;C. Ross;F. Salvat
电离辐射剂量学用于描述那些提供关于电离辐射与物质相互作用所沉积的能量的信息的测量或计算。辐射剂量学在几个领域都很重要，包括放射治疗、辐射防护和辐射的工业使用。已经开发了几种测量能量沉积的技术，其中最重要的是电离室和量热仪。这些技术构成了电离辐射主要测量标准的基础，这些主要标准要求某些关键参数的数值和不确定度估计，这些参数用于将测量结果与所需的量联系起来。使用蒙特卡罗技术计算辐射与物质的相互作用现在已经发展得很好，可以用来研究难以或不可能测量的问题的能量沉积。测量和计算都需要有关辐射与物质相互作用的基本量的知识。这些数据包括光子截面、电子阻止能力和创建离子对的平均能量，仅举几例。这些数据通常被称为“关键数据”。这份报告研究了从电子到碳离子的带电粒子的阻止能力的关键数据。为空气、石墨和液态水的平均激发能量分配了数值和不确定度，并提供了涵盖能量范围从1keV到1GeV或更高的阻止功率表。回顾、检查了空气、水和石墨的光子截面，并与相关测量结果进行了比较，以估计它们的不确定度。对于在空气中创建离子对的平均能量，建议使用这些值。总结了Fricke剂量学化学产额、石墨和液态水的热缺陷以及充气电离室的湿度修正因子和入射光子产生的初始离子对对测量电荷的修正。还总结了在低能光子和电子束中修正WAIR偏离推荐的渐近值的数据。讨论了建议更改的影响。重要的变化是自由气室空气比释动能测量的不确定度增加，60Co空气比释动能测量的不确定度降低约0.7%。推荐的石墨和液态水的阻挡能力与先前推荐的截止力相差1%。对于基于电离室的辐射剂量测量，根据吸收剂量对水量热计进行校准，测量到的水吸收剂量的变化不超过0.5%。
Ionizing radiation dosimetry is used to describe those measurements or calculations that provide information on the energy deposited by the interaction of ionizing radiation with matter. Radiation dosimetry is of importance in several areas, including radiation therapy, radiation protection, and the industrial use of radiation. Several techniques have been developed for measuring energy deposition, with ionization chambers and calorimeters being the most important. These techniques form the basis of primary measurement standards for ionizing radiation, and these primary standards require values and uncertainty estimates for certain key parameters used to relate the result of measurement to the desired quantity. The calculation of the interaction of radiation with matter using Monte Carlo techniques is now well developed and can be used to study energy deposition for problems where measurements are difficult or impossible. Both measurements and calculations require knowledge of basic quantities related to the interaction of radiation with matter. These include data on photon cross sections, electron stopping powers, and the average energy to create an ion pair, to name a few. These data are often referred to as “key data.” This Report examines key data for stopping powers for charged particles ranging from electrons to carbon ions. Values and uncertainties are assigned to the mean excitation energies for air, graphite, and liquid water, and tables of stopping powers covering the energy range from 1 keV to 1 GeV, or higher, are provided. Photon cross sections for air, water, and graphite are reviewed, examined, and compared with relevant measurements to estimate their uncertainties. Values are recommended for the average energy to create an ion pair in air, Wair. The available data for the chemical yield for Fricke dosimetry and for the heat defects for graphite and liquid water are summarized, as is the humidity correction factor for air-filled ionization chambers and the correction to the measured charge due to the initial ion pairs created by an incident photon. Data for the correction in photon and electron beams at low energies for the deviation of Wair from the recommended asymptotic value are also summarized. The impact of the recommended changes is discussed. Important changes are an increase in the uncertainty for air-kerma measurements with free-air chambers and a decrease of about 0.7 % in 60Co air-kerma measurements. The recommended stopping powers for graphite and liquid water differ by up to 1 % from those previously recommended. For radiation dosimetry based on ionization chambers calibrated against absorbed-dose-to-water calorimeters, changes in the measured absorbed dose to water will not exceed 0.5%.