1.1 本规程涵盖了使用酸性重铬酸银水溶液剂量测定系统测量电离辐射时水中吸收剂量的准备、测试和程序。该系统由剂量计和适当的分析仪器组成。为了简单起见，该系统将被称为重铬酸盐系统。根据影响量的影响，将重铬酸盐剂量计分为I型剂量计。重铬酸盐系统可以用作参考标准剂量测定系统或常规剂量测定系统。 1.2 本文件是一套标准之一，提供了在辐射处理中正确实施剂量测定的建议，并描述了实现符合ISO/ASTM实践要求的方法 52628 用于重铬酸盐剂量测定系统。应结合ISO/ASTM实践进行阅读 52628 . 1.3 本规程描述了重铬酸盐体系的分光光度分析程序。 1.4 这种做法仅适用于伽马辐射、X辐射/韧致辐射和高能电子。 1.5 只要满足以下条件，本规程适用: 1.5.1 吸收剂量范围为2 × 10 3. 至5 × 10 4. Gy。 1.5.2 吸收剂量率不超过600 Gy/脉冲（每秒12.5个脉冲），或不超过连续源7.5 kGy/s的等效剂量率 ( 1. ) . 2. 1.5.3 对于放射性核素伽马源，初始光子能量应大于0.6 MeV。对于韧致辐射光子，用于产生韧致辐射的电子的初始能量应等于或大于2MeV。 对于电子束，初始电子能量应大于8MeV。 注1: 给出的能量下限适用于直径为12mm的圆柱形剂量计安瓿。电子束可能需要对安瓿上的位移效应和剂量梯度进行校正 ( 2. ) 重铬酸盐系统可以通过使用更薄的（在光束方向上）剂量计容器以较低的能量使用（见ICRU报告35）。 1.5.4 剂量计的辐照温度应高于0°C，且应低于80°C。 注2: 剂量计响应的温度系数仅在5至50°C的范围内已知（见 5.2 ). 在该范围之外使用需要确定温度系数。 1.6 本标准并不旨在解决与其使用相关的所有安全问题（如有）。本标准的使用者有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 中给出了具体的预防说明 9.3 . 1.7 本国际标准是根据世界贸易组织技术性贸易壁垒委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认的标准化原则制定的。 ====意义和用途====== 4.1 重铬酸盐系统提供了一种可靠的方法来测量对水的吸收剂量。它是基于在酸性水溶液中通过电离辐射将重铬酸盐离子还原为铬离子的过程。 4.2 剂量计是在适当的容器（如密封的玻璃安瓿）中的高氯酸中含有银和重铬酸盐离子的溶液。溶液通过特定波长下的吸光度变化（减少）来指示吸收剂量( ( 3. ), ICRU报告80）。使用校准的分光光度计测量吸光度。

1.1 This practice covers the preparation, testing, and procedure for using the acidic aqueous silver dichromate dosimetry system to measure absorbed dose to water when exposed to ionizing radiation. The system consists of a dosimeter and appropriate analytical instrumentation. For simplicity, the system will be referred to as the dichromate system. The dichromate dosimeter is classified as a type I dosimeter on the basis of the effect of influence quantities. The dichromate system may be used as either a reference standard dosimetry system or a routine dosimetry system. 1.2 This document is one of a set of standards that provides recommendations for properly implementing dosimetry in radiation processing, and describes a means of achieving compliance with the requirements of ISO/ASTM Practice 52628 for the dichromate dosimetry system. It is intended to be read in conjunction with ISO/ASTM Practice 52628 . 1.3 This practice describes the spectrophotometric analysis procedures for the dichromate system. 1.4 This practice applies only to gamma radiation, X-radiation/bremsstrahlung, and high energy electrons. 1.5 This practice applies provided the following conditions are satisfied: 1.5.1 The absorbed dose range is from 2 × 10 3 to 5 × 10 4 Gy. 1.5.2 The absorbed dose rate does not exceed 600 Gy/pulse (12.5 pulses per second), or does not exceed an equivalent dose rate of 7.5 kGy/s from continuous sources ( 1 ) . 2 1.5.3 For radionuclide gamma sources, the initial photon energy shall be greater than 0.6 MeV. For bremsstrahlung photons, the initial energy of the electrons used to produce the bremsstrahlung photons shall be equal to or greater than 2 MeV. For electron beams, the initial electron energy shall be greater than 8 MeV. Note 1: The lower energy limits given are appropriate for a cylindrical dosimeter ampoule of 12 mm diameter. Corrections for displacement effects and dose gradient across the ampoule may be required for electron beams ( 2 ) . The dichromate system may be used at lower energies by employing thinner (in the beam direction) dosimeter containers (see ICRU Report 35). 1.5.4 The irradiation temperature of the dosimeter shall be above 0 °C and should be below 80 °C. Note 2: The temperature coefficient of dosimeter response is known only in the range of 5 to 50 °C (see 5.2 ). Use outside this range requires determination of the temperature coefficient. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in 9.3 . 1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 4.1 The dichromate system provides a reliable means for measuring absorbed dose to water. It is based on a process of reduction of dichromate ions to chromic ions in acidic aqueous solution by ionizing radiation. 4.2 The dosimeter is a solution containing silver and dichromate ions in perchloric acid in an appropriate container such as a sealed glass ampoule. The solution indicates absorbed dose by a change (decrease) in optical absorbance at a specified wavelength(s) ( ( 3 ), ICRU Report 80). A calibrated spectrophotometer is used to measure the absorbance.