Journal of the ICRU最新文献_第8页

3. Realization of Quantities by Primary Standards Laboratories 3.初级标准实验室量的实现

Journal of the ICRU Pub Date : 2014-04-01 DOI: 10.1093/jicru_ndw037

{"title":"3. Realization of Quantities by Primary Standards Laboratories","authors":"","doi":"10.1093/jicru_ndw037","DOIUrl":"https://doi.org/10.1093/jicru_ndw037","url":null,"abstract":"In principle, both kerma and absorbed dose can be determined for any material at any energy. Given the considerations noted above regarding secondaryphoton contributions and charged-particle equilibrium (CPE), it is not surprising that the relationship between kerma and absorbed dose changes significantly with energy and material. Because of the very limited beam penetration and the relatively low absorbed-dose rates involved, absorbed dose is very difficult to realize directly for kilovoltage x rays, although a few water calorimeter standards have been developed (see, e.g., de Prez and de Pooter, 2008; Krauss et al., 2012; Rapp et al., 2013). Most primary standards for these radiations are based on kerma, in particular on the determination of the air kerma using a free-air ionization chamber. At Co g-ray energies, the need for CPE would require a prohibitively large free-air chamber, and cavity-ionization chambers are used as primary standards. In more recent years, the direct determination of absorbed dose by graphite and water calorimetry has produced standards with an overall uncertainty that matches, and in some cases reduces, that derived from a determination of air kerma. Nevertheless, air kerma for Co g rays remains a very important reference quantity, particularly for standards laboratories. At the high energies produced by particle accelerators, the determination of air kerma free in air in these beams is no longer used to determine absorbed dose. In more recent years, absorbed-dose standards at high energies have been used, either directly for instrument calibrations or more commonly to determine values for correction factors that convert an ionization-chamber absorbed-dose calibration for Co g rays for use at higher energies (McEwen, 2010; Seuntjens et al., 2000). Several review articles describing the standards used for radiation dosimetry have been published in a special issue of Metrologia (Sharpe, 2009).","PeriodicalId":91344,"journal":{"name":"Journal of the ICRU","volume":"16 1","pages":"15 - 20"},"PeriodicalIF":0.0,"publicationDate":"2014-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88237752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

5. Recommended Values for Key Data 5. 关键数据的推荐值

Journal of the ICRU Pub Date : 2014-04-01 DOI: 10.1093/jicru_ndw038

引用次数: 1

3. Realization of Quantities by Primary Standards Laboratories 3.初级标准实验室实现数量

Journal of the ICRU Pub Date : 2014-04-01 DOI: 10.1093/jicru/ndw037

引用次数: 0

4. Charged-Particle Stopping Powers and Related Quantities 4. 带电粒子停止力和相关量

Journal of the ICRU Pub Date : 2014-04-01 DOI: 10.1093/jicru_ndw031

{"title":"4. Charged-Particle Stopping Powers and Related Quantities","authors":"","doi":"10.1093/jicru_ndw031","DOIUrl":"https://doi.org/10.1093/jicru_ndw031","url":null,"abstract":"Charged-particle stopping powers have been treated in detail in ICRU Report 37 (ICRU, 1984a), Report 49 (ICRU, 1993), and Report 73 (ICRU, 2005; Sigmund et al., 2009). In the present Report, consideration has been confined to electrons (and positrons), protons, and a particles for three key materials: graphite, air, and liquid water. Additionally, information on C ions in these materials has been included in recognition of their increasing use in radiation therapy. The stopping power quantifies the average energy loss per pathlength of charged particles in matter. In principle, the stopping power consists of three contributions, namely the electronic (or collision), the radiative, and the nuclear stopping power. The nuclear stopping power is negligible for electrons; it can be significant for light and heavy ions (ICRU, 1993; 2005), but only at rather low kinetic energies. A recommendation issued jointly by the ICRU and IAEA (Wambersie et al., 2004) calls “light ions” those nuclei with an atomic number equal to, or smaller than, that of neon nuclei (Z 1⁄4 10), leaving the name of “heavy ions” to all heavier nuclei. Results for the nuclear stopping power from ICRU Report 49 (1993) will be included in the tables presented in this Report for completeness. The radiative stopping power for electrons and positrons can be quite significant; for light and heavy ions, it is smaller to first approximation by a factor of (me/M) , where me is the rest mass of the electron and M the rest mass of the incident ion. Thus, the radiative stopping power can be ignored for protons and heavier ions at the kinetic energies considered in this Report.","PeriodicalId":91344,"journal":{"name":"Journal of the ICRU","volume":"8 1","pages":"21 - 30"},"PeriodicalIF":0.0,"publicationDate":"2014-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73649081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

5. Recommended Values for Key Data 5.关键数据的推荐值

Journal of the ICRU Pub Date : 2014-04-01 DOI: 10.1093/jicru/ndw038

引用次数: 5

4. Charged-Particle Stopping Powers and Related Quantities 4.带电粒子的阻止力及相关量

Journal of the ICRU Pub Date : 2014-04-01 DOI: 10.1093/jicru/ndw031

引用次数: 1

1. Introduction 1.简介

Journal of the ICRU Pub Date : 2014-04-01 DOI: 10.1093/jicru/ndw034

引用次数: 0

2. Definitions of Basic Quantities and Terms 2.基本数量和术语的定义

Journal of the ICRU Pub Date : 2014-04-01 DOI: 10.1093/jicru/ndw032