Provisional regulation of metrological supervision and management for radiation processing in China

In order to implement the “Law of metrology of the People's Republic of China” for guaranteeing the product quality of radiation processing, safeguarding State's interest and people's health, promoting the progress of radiation processing techniques, SBTS and SCST have jointly issued “the Provisional Regulation of Metrological Supervision and Management for Radiation Processing”, according to present situation of ionizing radiation measurement in radiation precessing plants. This is an administrative rule, which provides the regulation of radiation measurement licence for radiation precessing plants. SBTS has decided to establish the State Office of Technical Examination for Measurement Licence of Radiation Processing, which is attached to the National Institute of Metrology (NIM). Its main tasks include establishment of examination plans for radiation processing licence, organization of technical examination and other works related to the measurement regulation and performance of measurement supervision and regulation inradiation processing fields.     

Progress on standardization of electron beam dosimetry for radiation processing

The high dose standards and dissemination system of electron beams are being established at NIM. The graphite and/ or water calorimeters and liquid chemical dosimeter are to be accepted as standards. The transfer dosimeter selected are alanine/ESR dosimeter and radiochromic film (FWT - 60). Several kinds of radiochromic films, undyed cellulose triacetate, polyethylene and blue cellophane will be recommended as working dosimeter. A series of intercomparison studies are conducted between calorimeter and dichromate dosimeter. Agreement is found within 2%. Water calorimeters and dichromate dosimeters are used to make absolute dosimetric measurements of electron beams. These calibrated beams are then used to calibrate several types of dosimeters, such as alanine, radiochromic films, undyed and dyed polyethylene. Preliminary studies show that water calorimeter and dichromate dosimeter are reproducible and sufficiently accurate for electron beam calibration. The estimated overall uncertainty of the measurement is better than 5% at 95% confidence level.     

The electron dose monitoring and control system in EB radiation processing for wires and cables

This paper introduces a close-loop microcomputer control system used for EB radiation processing of wires and cables, which is based on the measurements and calculations of the absorbed dose distribution of 0.6–2.0 MeV electrons in circular compound materials. The calculation of electron energy deposition in 4-layer media is carried out by the bipartition model of electron transport.

The design ideas, system configuration and implementation of this control system governed by a 586 personal computer under windows 98 OS are described in this paper. The field operation results such as control precision and step response curves of this system are also given. The control system has been used for EB radiation processing of wires.     

European Quality Promotion Policy for improving the competitiveness of european industry

 The Community legislative policy for the free movement of industrial goods has evolved from an approach based purely on legislation and public intervention towards a more voluntary approach based on a homogeneous system combining regulatory and voluntary assessment of conformity with standards and/or customer specifications. This has led to an increased participation of the economic operators in the legislative process and a better reallocation of responsibilities between the public and private sectors. The European Union has now to go beyond legislation, standardisation and certification, in order to contribute further to increasing the competitiveness of European industry. At present, Community activities concentrate on reinforcing the Single Market and the necessary quality infrastructures, and in the proper implementation of existing legislation, in particular the application and interpretation of the CE marking requirements. These measures, however, do not solve all the problems relating either to conformity with regulatory requirements or to enhancing competitiveness. The European Quality Promotion Policy has the ambition of constituting above all an awareness policy to give political visibility and support to a European-wide range of quality instruments and actions. Simultaneously, it should be seen as a logical step on the road from conformity with safety regulations (in particular CE marking directives) to competitiveness and business excellence through quality management strategies.     

Standardization and regulatory control on radiation processing dosimetry in China

In 1983, in order to suit the rapid development of radiation processing, a programme of high dose standardization was initiated in China. As a result, a high dose measurement system for gamma - rays including primary standards, transfer standards and working dosimeters, has been established. In this paper, the scheme of dosimetry traceability to national standards for gamma - rays is illustrated. The aspects of standardization and the progress of dosimetry of radiation processing are also outlined.

In order to implement “the Law on Metrology of the Peoples Republic of China” and to guarantee the product quality of radiation processing. SBTS and SCTS have jointly issued “the Provisional Regulation of Metrological Supervision and Management for Radiation Processing”. A series of national standards, verification regulations and technical norms have been enacted and issued on the radiation processing dosimetry and on the approval of irradiation facilities. These documents are expected to play significant roles in the dose measurement standardization and the regularity control.     

Advancements in internationally accepted standards for radiation processing

Three subcommittees of the American Society for Testing and Materials (ASTM) are developing standards on various aspects of radiation processing. Subcommittee E10.01 “Dosimetry for Radiation Processing” has published 9 standards on how to select and calibrate dosimeters, where to put them, how many to use, and how to use individual types of dosimeter systems. The group is also developing standards on how to use gamma, electron beam, and x-ray facilities for radiation processing, and a standard on how to treat dose uncertainties. Efforts are underway to promote inclusion of these standards into procedures now being developed by government agencies and by international groups such as the United Nations' International Consultative Group on Food Irradiation (ICGFI) in order to harmonize regulations and help avoid trade barriers.

Subcommittee F10.10 “Food Processing and Packaging” has completed standards on good irradiation practices for meat and poultry and for fresh fruits, and is developing similar standards for the irradiation of seafood and spices. These food-related standards are based on practices previously published by ICGFI.

Subcommittee E10.07 on “Radiation Dosimetry for Radiation Effects on Materials and Devices” principally develops standards for determining doses for radiation hardness testing of electronics. Some, including their standards on the Fricke and TLD dosimetry systems are equally useful in other radiation processing applications.     

Utilization of carbohydrates by radiation processing

Upgrading and utilization of carbohydrates such as chitosan, sodium alginate, carrageenan, cellulose, pectin have been investigated for recycling these bio-resources and reducing the environmental pollution. These carbohydrates were easily degraded by irradiation and various kinds of biological activities such as anti-microbial activity, promotion of plant growth, suppression of heavy metal stress, phytoalexins induction, etc. were induced. On the other hand, some carbohydrate derivatives, carboxymethylcellulose and carboxymethylstarch, could be crosslinked under certain radiation condition and produce the biodegradable hydrogel for medical and agricultural use.     

AlanineESR Dosimetry system for routine use in radiation processing

A new alanine-polystyrene (PS) dosimeter prepared with simplified molding procedure and an automatic desk-top dose-reader of alanine dosimeter were developed for the purpose of routine use. Combination of these two allows us to apply a reliable alanine/ESR dosimetry system to routine dosimetric process control in industrial gamma radiation processing.     

A study on radiation sterilization of medical devices in the South of China

In this paper, directing at the peculiarity of south China, the technique and quality control of Co-80 r radiation sterilization of medical devices have been studied. Radiation dose setting is determined by the AAMI method. Experiment shows that radiation treatment has no effect upon the attributes of the products. Under the same condition of packing and environment, storing time of radiation sterilization is 4 times than that of sterilization by heat. Clinical appliances of 1000 carton products show that radiation sterilization products are safe and reliable.     

Dosimetry for radiation processing in Malaysia

The development of accurate and precise radiation dosimetry to control radiation-processing activity in Malaysia is discussed. Various procedures required to establish thorough dosimetry control for radiation processing in Malaysia is highlighted. The validity of the measurement process is guaranteed through regular quality control including standardization, calibration and intercomparison against other international institutes.     

Radiation effect studies on anticancer drugs, cyclophosphamide and doxorubicin for radiation sterilization

Two anticancer drugs, cyclophosphamide (CPH) and doxorubicin hydrochloride (DOXO), in powder form were exposed to a range of doses of ⁶⁰Co gamma and electron beam radiation to study the effects of ionizing radiation. Pharmacopoeia tests, discolouration, degradation products, effect of irradiation temperature and dose rate were investigated. CPH undergoes less than 2% degradation at 30 kGy. Chromatographic studies revealed formation of several trace level degradation products, discolouration and free radicals in the irradiated CPH. N,N-bis (2-chloroethyl) group in the molecule is particularly sensitive to radiation degradation. Irradiation to 5 kGy at low temperature (77 K) did not result in significant changes. DOXO was observed to be quite radiation resistant and did not undergo significant changes in its physico-chemical properties and degradation product profile. It can be radiation sterilized at normal sterilization dose of 25 kGy.     

Die Fehlertheorie des inneren Standards in der R?ntgenspektrometrie

Zusammenfassung Nachdem bereits in [3] und [4] die Fehlertheorie der Additionsmethode und des Verfahrens mit äußeren Standards behandelt worden war, wurden in vorliegender Arbeit die Überlegungen auf den inneren Standard ausgedehnt. Die Methode verwendet den Quotienten aus der Impulsrate des zu messenden Elements und der Impulsrate des mit konstanter Konzentration zugefügten Standardelements. Die Quotienten aus den Bruttoimpulsraten und den Nettoimpulsraten wurden bezüglich der Analysengenauigkeit und Nachweisgrenzen untersucht.

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Theory of errors of the internal standard in X-ray spectrometry

After having treated in [3] and [4] the theory of errors of the addition method and of the method of external standards, in this publication the considerations are extended to internal standards. This method uses the pulse rate of the element to be measured divided by the pulse rate of a standard element with constant concentration. The ratios of the gross pulse rates and the net pulse rates are studied with reference to the accuracies of analysis and the limits of detection.

     

Study on dosimetry of bremsstrahlung radiation processing

The dosimetry in high-power bremsstrahlung irradiation for the industrial processing has been studied. The dosimeter systems used are cylindrical ionization chamber to measure average exposure rate and CTA, clear PMMA and alanine dosimeters for routine dosimetry. The results gave some useful information on the measurement of average exposure rate using the ionization chamber. Clear PMMA and alanine dosimeters showed good characteristics for their usefulness as routine dosimeters for X-ray irradiation in the industrial processing.     

Catalytic PtPd bimetal nanocrystals with high-index facets for radiation injury repair

Radiotherapy is one of the most important clinical cancer treatments,which works mainly by delive ring a prescribed radiation dose to the tumor tissues.However,high doses of radiation may also lead many irreversible damages to the surrounding normal tissues.Thereby,how to effectively reduce these sideeffects has been a significant factor in influencing cancer therapeutic effect.In this work,we synthesized the hollow PtPd nanocubes with high-index facets,and investigated the radiation protection capability in vitro and in vivo.Our results showed the PtPd nanocrystals can decrease the ROS level and improve the survival rate of radiated cells.Meanwhile,survival rate of radiated mice can significantly increase from 0 to 30%after PtPd treatment.Consequently,the enzyme and ROS level in radiated mice can be recovered.     

Prospects for irradiation processing in the petroleum industry

The use of irradiation processing for processing petroleum crude oil is discussed. Aspects of radiation-thermal processing are shown in the experimental results for different types of crude oil that are characterized by essentially different hydrocarbon contents.     

Novel additives for accelerating radiation grafting and curing reactions

The value of additives for increasing yields in radiation grafting reactions is discussed. The possible significance of the work in concurrent grafting during radiation curing is evaluated. Additives previously found to be effective in radiation grafting and reviewed here include acids, inorganic salts, organic inclusion compounds like urea, multifunctional acrylates and methacrylates. Synergistic effects in performance between the first three groups and the latter two have also been observed. Two new classes of compounds as additives in radiation grafting are reported and their reactivities compared with the earlier series. These new additives are oligomer acrylates and photoinitiators. In a mechanistic discussion related to these additives, a novel proposal involving partitioning phenomena is outlined to explain their modes of action.     

Estimation of sample processing uncertainty for chlorpyrifos residue in cucumber

Sample processing is a very important component of uncertainty in analytical results. In order to have reliable results, the laboratory sample should be properly processed to obtain statistically homogenous matrix—before the representative test portions are withdrawn for analysis. The use of ¹⁴C-labeled compound is preferable because the analyte can be quantified without cleanup. The method is based on surface treatment of cucumber with ¹⁴C-chlorpyrifos, determination of ¹⁴C-chlorpyrifos activity in the replicate test portions of different size, and determination of the uncertainty of sample processing.     

Optoelectronic reader for CET dosimeter, a radiation accident chemical dosimetry system

The use of chlorobenzene–ethanol–trimethylpentane solution (CET) in radiation dosimetry is based on radiolytic formation of hydrochloric acid which protonates a pH indicator, thymolsulphonphthalein. The high molar absorptivity of its red form at 552 nm is responsible for a high sensitivity of the system: doses in the range 0.2–15 Gy can be measured. Together with a visual colour comparator it has formed a personnel dosimetry system suitable for accident and civil defense use.

A newly constructed optoelectronic reader with two two-colour light emitting diodes (550 and 690 nm) as light sources and a silicone photocell as a detector uses the differential absorbance at these two wavelengths as the response. The response is a direct function of dose and can be recorded and processed electronically.     

Effect of gamma radiation on growth and survival of common seed-borne fungi in India

The present work describes radiation-induced effects of major seeds like Oryza sativa Cv-2233, Oryza sativa Cv-Shankar, Cicer arietinum Cv-local and seed-borne fungi like Alternaria sp., Aspergillus sp., Trichoderma sp. and Curvularia sp. ⁶⁰Co gamma source at 25 °C emitting gamma ray at 1173 and 1332 keV energy was used for irradiation. Dose of gamma irradiation up to 3 kGy (0.12 kGy/h) was applied for exposing the seed and fungal spores. Significant depletion of the fungal population was noted with irradiation at 1–2 kGy, whereas germinating potential of the treated grain did not alter significantly. However, significant differential radiation response in delayed seed germination, colony formation of the fungal spores and their depletion of growth were noticed in a dose-dependent manner. The depletion of the fungal viability (germination) was noted within the irradiation dose range of 1–2 kGy for Alternaria sp. and Aspergillus sp., while 0.5–1 kGy for Trichoderma sp. and Curvularia sp. However, complete inhibition of all the selected fungi was observed above 2.5 kGy.     

Evaluation of plastic packaging materials used in radiation sterilized medical products and food

This paper studied the results of evaluation on resistance to radiation, moisture permeability, bacteria permeability, tensile strength, elongation at break and sealing ability for several plastic films available on the market. The result shows that nylon, sarin, and polyethylene complex films, high and low density polyethylene films are applicable for packing of radiation sterilized products.