ICRP Publication 105. Radiation protection in medicine

This report was prepared to underpin the Commission's 2007 Recommendations with regard to the medical exposure of patients, including their comforters and carers, and volunteers in biomedical research. It addresses the proper application of the fundamental principles (justification, optimisation of protection, and application of dose limits) of the Commission's 2007 Recommendations to these individuals. With regard to medical exposure of patients, it is not appropriate to apply dose limits or dose constraints, because such limits would often do more harm than good. Often, there are concurrent chronic, severe, or even life-threatening medical conditions that are more critical than the radiation exposure. The emphasis is then on justification of the medical procedures and on the optimisation of radiological protection. In diagnostic and interventional procedures, justification of procedures (for a defined purpose and for an individual patient), and management of the patient dose commensurate with the medical task, are the appropriate mechanisms to avoid unnecessary or unproductive radiation exposure. Equipment features that facilitate patient dose management, and diagnostic reference levels derived at the appropriate national, regional, or local level, are likely to be the most effective approaches. In radiation therapy, the avoidance of accidents is a predominant issue. With regard to comforters and carers, and volunteers in biomedical research, dose constraints are appropriate. Over the last decade, the Commission has published a number of documents that provided detailed advice related to radiological protection and safety in the medical applications of ionising radiation. Each of the publications addressed a specific topic defined by the type of radiation source and the medical discipline in which the source is applied, and was written with the intent of communicating directly with the relevant medical practitioners and supporting medical staff. This report consolidates that advice.     

Radiation and your patient: a guide for medical practitioners

This didactic text is devoted to the protection of patients against unnecessary exposure to ionising radiation. It is organised in a questions-and-answers format. There are obvious benefits to health from medical uses of radiation, in x-ray diagnostics, interventional radiology, nuclear medicine, and radiotherapy. However, there are well-established risks from high doses of radiation (radiotherapy, interventional radiology), particularly if improperly applied, and possible deleterious effects from small radiation doses (such as those used in diagnostics). Appropriate use of large doses in radiotherapy prevents serious harm, but even low doses carry a risk that cannot be eliminated entirely. Diagnostic use of radiation requires therefore such methodology that would secure high diagnostic gains while minimising the possible harm. For assessment of the risk, a quantitative measure of exposure is a necessary prerequisite. Therefore, dosimetric quantities are explained and defined (absorbed dose, effective dose). Basic facts are presented on mechanisms of action of ionising radiations on living matter. Undesired deleterious effects in man are categorised into two categories. The first one comprises sequelae resulting from massive cell killing (the so-called deterministic effects), requiring a high dose for their manifestation (exceeding the threshold dose). The second category includes those effects originating from mutational changes in the cellular DNA. These may eventually lead to development of radiation-induced cancer and to hereditary changes, transmitted to descendants of exposed individuals after irradiation of their gonads. Data on the magnitude of threshold doses for cell killing effects are presented. On the basis of experimental, clinical, and epidemiological evidence, assessment is also given of the probability with which cancers and hereditary mutations may be induced by doses of various magnitudes, most likely without a threshold dose (below which no effect would obtain). The text provides ample information on opportunities to minimise doses, and therefore the risk from diagnostic uses of radiation. This objective may be reached by avoiding unnecessary (unjustified) examinations, and by optimising the procedures applied both from the standpoint of diagnostic quality and in terms of reduction of the excessive doses to patients. Optimisation of patient protection in radiotherapy must depend on maintaining sufficiently high doses to irradiated tumours, securing a high cure rate, while protecting the healthy tissues to the largest extent possible. Problems related to special protection of the embryo and fetus in the course of diagnostic and therapeutic uses of radiation are presented and practical solutions are recommended. This issue of the Annals of the ICRP also includes a brief report concerning Diagnostic Reference Levels in medical imaging: Review and additional advice.     

职业性急性放射性皮肤损伤病例诊断评价

采取问卷调查形式,收集并统计、分析2016—2019年确诊的6例职业性急性放射性皮肤损伤病例。结果表明,工业辐照和工业探伤是导致工人职业性急性放射性皮肤损伤的重点工种,放射单位应加强放射工作人员的培训,尤其是岗前培训,提高防护意识;工人进入放射工作场所,应佩戴常规剂量计,并在关键岗位佩戴报警式剂量计;诊断职业性急性放射性皮肤损伤涉及诊断医师对标准的熟悉程度和严格把握采用,关键在于明确的受照剂量和临床表现。     

鲻鱼解剖学模型剂量计算及与整体模型的比较

以秦山地区的鲻鱼为例,进行现场取样测量,根据实测数据建立了区分组织/器官的解剖学模型。采用MCNP程序对¹³⁷Cs和⁹⁰Sr发射的射线对组织和器官的能量吸收份额进行模拟,并进行剂量计算。作为比较,同时建立了具有相同几何尺寸的整体均匀模型,用传统方法进行剂量计算。结果为：对于内照射,在生物内部器官具有较高浓集因子的情况下,生物体局部剂量比较大,使用整体均匀模型的估算方法是偏不保守的;对于外照射,解剖学模型的计算值小于整体均匀模型。     

国际放射防护委员会的剂量系数的可靠性

在评价公众成员摄入放射性核素的辐射危害时，需估算每单位摄入量所致的剂量。摄入放射性素后器官或民受到的剂量是受到的剂量是通过生物学模型和剂量学模型来确定的，因此剂量也必须根据模型来确定。文中初步探讨了国际放射防护委员会给出的剂量系数的可靠性问题。文中首先说明了估算剂量系数的概念和方法，然后分析了剂量系数估算中，采用胃肠道模型，呼吸道模型，系统生物动力学模型和剂量学模型所遇到的不确定度的各种主要来源。     

辐射防护剂和治疗剂的研究进展

随着核能与核技术的迅速发展及广泛应用,人们接触电离辐射的机会日益增多。辐射防护剂和治疗剂的应用倍受关注,但目前使用的许多辐射防护剂和治疗剂都不太理想。研究人员一直致力于研究高效、低毒的天然辐射防护剂。本文主要关注了化学类、植物和天然中草药的辐射防护剂以及细胞因子和干细胞辐射治疗剂的应用前景。氨磷汀(WR-2721)及相关化合物最具市场前景,但是严重的不良反应限制其临床应用。植物提取物和天然中草药具有毒性小、价格相对低廉、可以口服给药,并且可以通过多种机制发挥作用的优势,因此成为国内外研究关注的热点。细胞因子治疗能够预防或减少急性辐射综合症(ARS)。间充质干细胞(MSC)具有分泌造血生长因子、重建造血微环境、低免疫原性、易于外源基因转染和表达等优点,将其应用于急性辐射损伤的临床治疗具有十分广阔的前景。因此,植物和中草药作为辐射防护剂和MSC作为放射治疗剂的协同应用可能是未来研究的趋势。     

The 2007 Recommendations of the International Commission on Radiological Protection. ICRP publication 103

These revised Recommendations for a System of Radiological Protection formally replace the Commission's previous, 1990, Recommendations; and update, consolidate, and develop the additional guidance on the control of exposure from radiation sources issued since 1990. Thus, the present Recommendations update the radiation and tissue weighting factors in the quantities equivalent and effective dose and update the radiation detriment, based on the latest available scientific information of the biology and physics of radiation exposure. They maintain the Commission's three fundamental principles of radiological protection, namely justification, optimisation, and the application of dose limits, clarifying how they apply to radiation sources delivering exposure and to individuals receiving exposure. The Recommendations evolve from the previous process-based protection approach using practices and interventions by moving to an approach based on the exposure situation. They recognise planned, emergency, and existing exposure situations, and apply the fundamental principles of justification and optimisation of protection to all of these situations. They maintain the Commission's current individual dose limits for effective dose and equivalent dose from all regulated sources in planned exposure situations. They reinforce the principle of optimisation of protection, which should be applicable in a similar way to all exposure situations, subject to the following restrictions on individual doses and risks; dose and risk constraints for planned exposure situations, and reference levels for emergency and existing exposure situations. The Recommendations also include an approach for developing a framework to demonstrate radiological protection of the environment.     

辐射事故中确定性健康危害的剂量学评价方法(Ⅰ)

确定性效应是辐射事故中主要关心的健康危害。辐射事故照射,除大剂量急性照射情况外,更多的还有受照延续时间不等、照射水平不一的多次受照情况,甚至尚有数天内连续受照的。本文从辐射效应的“线性-平方”模型出发,借助目前已经掌握的确定性效应的剂量阈值,针对剂量的不同时间分布,集中探讨低LET辐射事故中评价确定性健康危害的剂量学方法。引用了分割照射和延续照射的外推剂量概念,提出了外推剂量可加原理和等外推剂量等效应原理。     

不同类型事故受照人员生物剂量估算和辐射影响评价

结合近年来发生的数起不同类型的辐射事故,对指导临床救治的生物剂量估算过程进行报道,特别针对辐射生物剂量学的难点问题,如迁延照射、大剂量照射及快速剂量估算等瓶颈问题,采取不同手段和方法给予解决,并对辐射远后效应做出评价。     

大鼠尿液中γ辐射损伤特征代谢物

目的：探讨γ辐射对大鼠尿液代谢物的影响,初步筛选与γ辐射损伤密切相关的特征尿代谢物。方法采用核磁共振技术对60 Coγ射线单次照射（剂量率0．7 Gy/min ,剂量6．0 Gy ）后不同时间点（照射前1天及照射后第1、2、3、4、8、18、30、45天）和分次照射后不同累积剂量点（剂量率18 mGy/min ,累积剂量分别为0、0．2、0．4、0．6、0．8、1．0 Gy ）大鼠尿液的代谢成分进行检测。主成分分析法（PCA ）和偏最小二乘法（PLS-DA ）分析检测数据。筛选单次照射和分次照射所致辐射损伤的共同特征代谢物。结果单次照射后,大鼠尿牛磺酸、脯氨酸相对含量在照后第1～45天持续偏高;分次照射后,尿牛磺酸、脯氨酸相对含量均有随剂量增加而增加的趋势。结论γ辐射可导致大鼠长期代谢紊乱。尿牛磺酸、脯氨酸相对含量与照射剂量有相关性,可作为γ辐射损伤的特征代谢物。     

Annals of the ICRP. A report of: doses to infants from ingestion of radionuclides in mothers' milk

In the present report, ICRP provides information on radiation doses to the infant due to intakes of radionuclides in maternal milk. As in Publication 88 (ICRP, 2001) on doses to the embryo and fetus following intakes of radionuclides by the mother, intakes by female members of the public and female workers are addressed. Acute and chronic intakes are considered at various times before and during pregnancy as well as during the period of breastfeeding. Dose coefficients per unit intake by the mother (Sv/Bq) are given for the selected radionuclides of the same 31 elements for which age-specific biokinetic models were given in Publications 56, 67, 69, and 71 (ICRP, 1989, 1993, 1995a,b). For these elements, doses were calculated for the most radiologically significant natural or artificial radionuclides that might be released into the environment due to various human activities. Dose coefficients are also given in this report for radionuclides of an additional four elements: sodium, magnesium,phosphorus, and potassium. Relevant human and animal data on elemental and radionuclide transfer to milk are reviewed. The biokinetic models for adults given in earlier ICRP publications are adapted to include transfer to milk. Model predictions of fractional transfer of ingested or inhaled activity to milk are discussed in the report, and the corresponding dose coefficients for the infant are compared with dose coefficients for in utero exposure, as given in Publication 88 (ICRP, 2001). Illustrative information is also given on doses to the female breast from radionuclides in breastmilk, and external doses received by the child from radionuclides retained in the tissues of the mother. For the additional elements considered in this report, but not in Publication 88 (ICRP,2001), information is also given on doses to the embryo and fetus following maternal intakes of radioisotopes during or before pregnancy. A CD-ROM is to be issued giving data that will supplement the information given in this report. In addition to the dose coefficients given here, committed equivalent doses to the various organs and tissues of the offspring will be given. Dose coefficients will also be given for inhalation of a range of aerosol sizes for the selected radionuclides of the elements covered by this report.     

Radiation and temperature survivability of multimode step-indexfluorine-doped silica fibers

In a search for optical fibers appropriate for long-term use in nuclear reactor instrumentation, effects of gamma radiation and high temperature on attenuation losses were investigated in three types of fiber. All of the fibers had silica cores with fluorine-doped silica cladding. Fibers with polyimide and aluminium coatings and uncoated fibers were tested. Samples were exposed to gamma radiation at dose rates ranging from 8.2 krad/h to 920 krad/h, with total doses up to 60 Mrad. The effects of heating the fibers, either concurrently with the radiation exposure or separately, were investigated. Heating irradiated fibers to 200°C generally reduced attenuation by annealing of radiation-induced defects. Higher temperatures caused rapid deterioration of fibers. A similar effect was observed when fibers were heated to above 200°C in the absence of radiation. Raising the temperature appears to suppress color centre formation, but beyond a threshold limit, higher temperatures result in jacket or cladding damage with net degradation     

辐射防护剂的研究进展

人体的细胞和组织受到一定剂量射线照射后,其结构和功能均会发生变化。其主要机制为,电离产生大量自由基后,破坏细胞DNA及内部端粒酶结构,破坏线粒体膜电位稳态,进而导致细胞的凋亡、异常增殖、功能发生改变。本文就现有主要的辐射防护剂和天然药物的抗辐射功能进行简要综述,并阐述其中可能的机制。其中氢巯基类辐射防护剂主要成分为N-乙酰半胱氨酸;维生素类主要是维生素E和维生素C起作用;多糖的种类繁多,植物多糖具有辐射防护作用;免疫调节剂和细胞因子中的粒细胞集落因子有较好的防辐射功效;而天然中药成分14-去氧-11,12-二去氢穿心莲内酯作为一种新的防辐射药物,其作用机制值得进一步深入研究。     

Dose Conversion Coefficients for External Photons Based on ICRP 1990 Recommendations

Monte Carlo calculations were performed to estimate the effective doses E for external photons based on the recent proposals in the ICRP 1990 Recommendations. Twelve photon energies between 17 keV and 8.5 MeV and eleven irradiation geometries were selected to be applicable to many exposure conditions encountered in the working and living environment. A MIRD-based unisex phantom was used in conjunction with the Monte Carlo transport code MORSE-CG. The results were presented as a form of dose conversion coefficients transforming the air kerma or fluence in free air to the effective dose. These coefficients were given in graphical and tabular forms. Analyses of organs' fractional contribution to E showed that the gonadal exposure has generally a great contribution for all the geometries except the incidence from above. A comparison of conversion coefficients with other results gave a reasonably satisfactory agreement. Finally, the ambient dose equivalent H ^*(10), one of the operational quantities proposed by the ICRU, was found to give conservative estimates of E for most of the irradiation geometries considered, but it gives a considerable overestimate of E at the incidences from above and below.     

Radiation Exposure Normalization Taking Account of Specific Effects at Low Doses and Dose Rates

Epidemiological studies of the consequences of radiation exposure of humans already prove that at low dose rates 85% of radiation-induced cancer arises only above a threshold dose from 0.3 to 30 Sv, and sometimes radiation hormesis occurs. In this question, the ICRP and the RNCRP rely on unreliable information and an incorrect linear zero-threshold dose–effect relation model. Two new principles of radiation safety are proposed and a model for normalizing radiation exposure on the basis of the new facts is also proposed. The model retains the adopted maximum lifetime individual risk of death due to radiation-induced cancer, but the dose in organs determines this risk. For uniform whole body radiation exposure, the dose creating the indicated limit can be taken as the equivalent dose. It will equal 150 mSv/yr. According to the model, during the initial years of radiation exposure there is no carcinogenic risk at all. The need for normalizing the content of radionuclides in the human body and introducing other changes in the norms is substantiated.     

Radiation dose to patients from radiopharmaceuticals (addendum 2 to ICRP publication 53)

A joint Task Group of ICRP Committees 2 (Doses from Radiation Exposures) and 3 (Protection in Medicine; lead Committee for this report) has prepared a compilation of data on radiation dose to patients from radiopharmaceuticals. The report provides biokinetic models, absorbed doses, and effective doses, using ICRP Publication 60 dosimetry, for 10 new radiopharmaceuticals: [Methyl-11C]thymidine; [2-11C]thymidine; 14C urea (incl. carbon dioxide and bicarbonate); 15O water; 99mTc HIG, Pertechnegas, Technegas, and tetrofosmin; and 111In HIG and octreotide. It also provides recalculated dose data for the 19 most frequently used radiopharmaceuticals from ICRP Publication 53, using ICRP Publication 60 dosimetry, viz. 18F FDG; 51Cr EDTA; 67Ga citrate; 75Se SeHCAT; 99mTc DMSA, DTPA, RBC, IDA, large colloids, WBC, MAA, non-absorbable markers, pertechnetate, and phosphates and phosphonates; 123I Hippuran and MIBG; 131I Hippuran and NP59; and 201Tl thallous ion. Printing errors detected in ICRP Publication 53 are also listed. Furthermore, the report reproduces with minor corrections and updates, and therefore supersedes, the information on 6 radiopharmaceuticals given in Addendum 1 to ICRP Publication 53: 3H neutral fat and fatty acids; 14C neutral fat and fatty acids; 68Ga EDTA; and 99mTc HM-PAO, MAG3, and MIBI. There is an integrated index to all radiopharmaceuticals treated in ICRP publications so far, including a listing of effective doses per unit activity administered to adults. This issue of the Annals of the ICRP also includes an Addendum to ICRP Publication 72 concerning age-dependent doses to members of the public from intakes of radionuclides.     

Avoidance of radiation injuries from medical interventional procedures.

Interventional radiology (fluoroscopically-guided) techniques are being used by an increasing number of clinicians not adequately trained in radiation safety or radiobiology. Many of these interventionists are not aware of the potential for injury from these procedures or the simple methods for decreasing their incidence. Many patients are not being counselled on the radiation risks, nor followed up when radiation doses from difficult procedures may lead to injury. Some patients are suffering radiation-induced skin injuries and younger patients may face an increased risk of future cancer. Interventionists are having their practice limited or suffering injury, and are exposing their staff to high doses.In some interventional procedures, skin doses to patients approach those experienced in some cancer radiotherapy fractions. Radiation-induced skin injuries are occurring in patients due to the use of inappropriate equipment and, more often, poor operational technique. Injuries to physicians and staff performing interventional procedures have also been observed. Acute radiation doses (to patients) may cause erythema at 2 Gy, cataract at 2 Gy, permanent epilation at 7 Gy, and delayed skin necrosis at 12 Gy. Protracted (occupational) exposures to the eye may cause cataract at 4 Gy if the dose is received in less than 3 months, at 5.5 Gy if received over a period exceeding 3 months.Practical actions to control dose to the patient and to the staff are listed. The absorbed dose to the patient in the area of skin that receives the maximum dose is of priority concern. Each local clinical protocol should include, for each type of interventional procedure, a statement on the cumulative skin doses and skin sites associated with the various parts of the procedure. Interventionists should be trained to use information on skin dose and on practical techniques to control dose. Maximum cumulative absorbed doses that appear to approach or exceed 1 Gy (for procedures that may be repeated) or 3 Gy (for any procedure) should be recorded in the patient record, and there should be a patient follow-up procedure for such cases. Patients should be counselled if there is a significant risk of radiation-induced injury, and the patient's personal physician should be informed of the possibility of radiation effects. Training in radiological protection for patients and staff should be an integral part of the education for those using interventional techniques. All interventionists should audit and review the outcomes of their procedures for radiation injury. Risks and benefits, including radiation risks, should be taken into account when new interventional techniques are introduced.A concluding list of recommendations is given. Annexes list procedures, patient and staff doses, a sample local clinical protocol, dose quantities used, and a procurement checklist.     

核电站辐射防护的现状和趋势

核电站辐射防护的任务主要包括 :个人和集体剂量控制 ,放射性物质管理以防止失控和污染扩散 ,辐射事故预防 ,其中最能衡量核电站辐射防护管理和 ALARA实施水平的指标是集体剂量控制。控制集体剂量可以从控制剂量率水平、控制照射时间和控制受照人数 3个方面着手 ,而这 3个方面的控制又可以通过源项控制、安全文化培养、工作过程管理和优化等措施来达到。在日本举行的 IRPA-1 0上发表的有关报告 ,也表明目前的核电站辐射防护有以下 3个特点和趋势 :1 )重视核电站安全文化的培养 ;2 )重视对放射性源项的监测和控制 ;3 )重视对高风险工作过程的 ALARA控制。本文对这些方面分别进行了阐述。     

ICRP Publication 114. Environmental protection: transfer parameters for reference animals and plants

In Publication 103 (ICRP, 2007), the Commission included a section on the protection of the environment, and indicated that it would be further developing its approach to this difficult subject by way of a set of Reference Animals and Plants (RAPs) as the basis for relating exposure to dose, and dose to radiation effects, for different types of animals and plants. Subsequently, a set of 12 RAPs has been described in some detail (ICRP, 2008), particularly with regard to estimation of the doses received by them, at a whole-body level, in relation to internal and external radionuclide concentrations; and what is known about the effects of radiation on such types of animals and plants. A set of dose conversion factors for all of the RAPs has been derived, and the resultant dose rates can be compared with evaluations of the effects of dose rates using derived consideration reference levels (DCRLs). Each DCRL constitutes a band of dose rates for each RAP within which there is likely to be some chance of the occurrence of deleterious effects. Site-specific data on Representative Organisms (i.e. organisms of specific interest for an assessment) can then be compared with such values and used as a basis for decision making. It is intended that the Commission's approach to protection of the environment be applied to all exposure situations. In some situations, the relevant radionuclide concentrations can be measured directly, but this is not always possible or feasible. In such cases, modelling techniques are used to estimate the radionuclide concentrations. This report is an initial step in addressing the needs of such modelling techniques. After briefly reviewing the basic factors relating to the accumulation of radionuclides by different types of biota, in different habitats, and at different stages in the life cycle, this report focuses on the approaches used to model the transfer of radionuclides through the environment. It concludes that equilibrium concentration ratios (CRs) are most commonly used to model such transfers, and that they currently offer the most comprehensive data coverage. The report also reviews the methods used to derive CRs, and describes a means of summarising statistical information from empirical data sets. Emphasis has been placed on using data from field studies, although some data from laboratory experiments have been included for some RAPs. There are, inevitably, many data gaps for each RAP, and other data have been used to help fill these gaps. CRs specific to each RAP were extracted from a larger database, structured in terms of generic wildlife groups. In cases where data were lacking, values from taxonomically-related organisms were used to derive suitable surrogate values. The full set of rules which have been applied for filling gaps in RAP-specific CRs is described. Statistical summaries of the data sets are provided, and CR values for 39 elements and 12 RAP combinations are given. The data coverage, reliance on derived values, and applicability of the CR approach for each of the RAPs is discussed. Finally, some consideration is given to approaches where RAPs and their life stages could be measured for the elements of interest under more rigorously controlled conditions to help fill the current data gaps.     

Experimental Estimation of Effective Dose for Irradiation Geometries in Working Places According to ICRP 1990 Recommendations

Conversion coefficients for the equivalent dose in tissue or organ and the effective dose were estimated experimentally with BeO-TLDs inside a male RANDO phantom against external photon radiation. The experiments were performed for Superior-Inferior and Inferior-Superior geometries in cases of unusual irradiation conditions which were occasionally seen in high radiation areas. For these geometries, a parallel photon beam to the long axis of phantom was irradiated. To evaluate the shielding effect of legs in the Inferior-Superior geometry, measurements with and without legs were done by linking a leg phantom, made of tissue equivalent material. The difference of effective dose by the leg phantom was found to be about 20% in the energy range studied.

The effective dose was calculated from the equivalent dose in tissues or organs by modifying the tissue weighting factors given in ICRP Publ. 60 for males, and the effective dose equivalent according to ICRP Publ. 26 was also derived to be compared with the effective dose. In this experiment, the effective dose was estimated lower than the effective dose equivalent about 40% for Superior-Inferior geometry and about 20% for Inferior-Superior geometry due to the change in tissue weighting factors. However, there was no remarkable difference for Anterior-Posterior geometry.