Radiation protection standards.
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With the aim of optimizing the UV radiation protecting efficacy of N-acetylcysteine (NAC), the following topically applied cysteine derivatives were investigated: N-acetylcysteine ethylester (NACET), S-acetylcysteine ethylester (SACET), cysteine ethylester (CYSET), N,S-diacetylcysteinamide (SNACA), N,S-diacetylcysteine (SNAC) and N,S-diacetylcysteine ethylester (SNACET). As a measure for protection the inhibition of in vivo irreversible photobinding of the labelled phototoxic drugs chlorpromazine (CPZ) and 8-methoxypsoralen (8-MOP) to rat epidermal biomacromolecules was used. The duration of protection of the cysteine derivatives was shortened by S-acetylation, N-acetylation and carboxyl derivatization. Compounds with a free thiol group showed a long-lasting presence in the stratum corneum, probably by the formation of mixed disulphides with proteins. The intrinsic protecting efficacy with respect to the total epidermis increased in the order CYSET < SNACET,SNACA,SACET < NACET, SNAC,NAC. The results of this study are discussed in view of susceptibility to oxidation, epidermal bioavailability and metabolic activation. With respect to the viable epidermis we postulate that NACET and SNAC have the most promising properties as UV protective agents.
The evolution of the Russian Federation legislation and regulation concerning the radiation protection of the population, the environment and the monitoring is presented. The main federal laws--"On the Environmental Protection", "On the Atomic Energy Use", "On the Radiation Safety of Population", etc. as well as standards of radiation safety, sanitary and hygienic norms, international agreements and conventions are briefly summarized. Main directions towards further improvement of the environmental radioprotection regulation in Russia are pointed out.
During the last few months, administrations of both the European Community and Germany have brought up several recommendations and changes concerning radiation protection. The European changes must become national law by 13th May, 2000. The changes focus on better protection of children and pregnant women. When performing X-ray examinations, strict indications will have to be observed.
The paper outlines the ways of technological progress in controlling and recording the dosage loading on the patients undergone X-ray studies. Differences have been established in the concepts "an effective dose" which are proposed by the International Radiation Protection Committee and given in the documents issued by the National State Committee for Standardization. The paper also describes the accepted methods for regulating the patients' dosage loads, which determine the ways of improving X-ray equipment and means of patients' individual protection.
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AIM: The lately updated German guideline on radiation protection in medicine (Richtlinie Strahlenschutz in der Medizin) requires the physician who administers radioactive substances for therapy, to perform and document follow-ups. In order to decrease the administrative burden, an electronic database was developed that interfaces with a word processing software to generate written reports and statistic analysis. METHODS: Based on Microsoft Access and Microsoft Visual Basic a database was created to monitor patients with benign and malignant thyroid disorders after radioiodine therapy. It permits automatic creation of therapy documents and necessary patient reports in Microsoft Word. Intuitive handling, third level of normalization in database architecture and automatic plausibility checks guarantee integrity of the data and the efficacy of the database. RESULTS, CONCLUSION: The new software has been a success in over 1500 patients and over 3800 in- and outpatient therapies and visits. The effort of data entry is easily offset by the automatic generation of the necessary patient reports. The required supervision of the follow-up appointments is now also user-friendly and efficient.
The various instruments used for neutron spectrometry can be divided into four categories. Within each of these categories, the underlying measurement principle for all devices is essentially the same. The applications of the instruments within each group to spectrometry for radiation protection are reviewed.
While interventional radiological procedures are minimally invasive and beneficial to patients, some complex and lengthy fluoroscopically guided procedures may cause radiation-induced skin injuries. Interventional radiologists should be aware of threshold doses, actual dose rates of specific X-ray equipment, and practical techniques to control the patient's cumulative skin dose. The International Commission on Radiation Protection recommends that the maximum dose to the skin be recorded when it approaches 1 Gy (for procedures that may be repeated) or 3 Gy (for any procedure) and that patient follow-up be provided in the latter situation. To reduce operator exposure, it is essential to avoid direct exposure of the primary beam to the hands in procedures such as transhepatic biliary drainage. During vascular interventions, the majority of operator exposure is caused by scatter radiation from the patient. Almost every effort to reduce patient dose secondarily reduces scatter radiation to the operator as well. The overcouch X-ray tube system is associated with higher exposure to the hands and eyes, and should not be used for complicated procedures. Appropriate shields help in reducing scatter to the operator.
Intra-arterial iodine-131 labelled Lipiodol therapy for liver cancer has been investigated for safety and efficacy over a number of years, but data on radiation exposure of personnel have remained unavailable to date. The aim of this study was to assess the radiation exposure of the physician during intra-arterial 131I-Lipiodol therapy for liver malignancies and to develop appropriate radiation protection measures and equipment. During 20 intra-arterial administrations of 131I-Lipiodol (1110-1924 MBq), radiation dose equivalents (RDE) to the whole body, fingers and eyes of the physician were determined for (a) conventional manual administration through a shielded syringe, (b) administration with an automatic injector and (c) administration with a lead container developed in-house. Administration by syringe resulted in a finger RDE of 19.5 mSv, an eye RDE of 130-140 microSv, and a whole-body RDE of 108-119 microSv. The injector reduced the finger RDE to 5 mSv. With both technique (a) and technique (b), contamination of angiography materials was observed. The container allowed safe transport and administration of the radiopharmaceutical from 4 m distance and reduced the finger RDE to <3 microSv and the eye RDE to <1 microSv during injection. During femoral artery compression, radiation exposure to the fingers reached 170 microSv, but the whole-body dose could be reduced from a mean RDE of 114 microSv to 14 microSv. No more contamination occurred. In conclusion, radiation exposure was high when 131I-Lipiodol was administered by syringe or injector, but was significantly reduced with the lead container.
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The occurrence of micronuclei proved to be a sensitive biological indicator of clastogenic effects of many chemical and physical agents. The possibility of using the micronucleus technique in radiation protection as an alternative to the traditional chromosomal analysis has recently been followed with increasing interest. This review outlines the main biological and practical aspects of the micronucleus assay and discusses its potential to serve as a rapid and reliable measure of radiation overexposures and hypersensitivities.
Comparison of the 226Ra ingestion permitted by a radiation protection system that limits dose equivalent, with that permitted by the ICRP system and by the ICRP system modified through the use of the Norris retention function in place of the ICRP alkaline earth model, shows that the total ingested activity and the total committed dose equivalent to bone-surface tissues are approximately the same under the three protection systems when exposure occurs at the maximum permissible level for 50 y. Under the dose-equivalent-limitation system, annual ingestion decreases from 451 kBq during the first year to 36 kBq during the fiftieth year. The total ingestion equals 3.45 MBq. Annual committed dose equivalent decreases from 3.6 Sv during the first year to 0.3 Sv during the fiftieth year. The total committed dose equivalent equals 27 Sv. Under the ICRP system and its modified version, the annual limits on intake are constant with time at 70 kBq and 63 kBq, respectively. The total intakes are 3.50 MBq and 3.15 MBq. The annual committed dose equivalent is also constant with time at 0.5 Sv for both versions. The total committed dose equivalent is 25 Sv. These results suggest that a pure dose equivalent limitation system similar to that which has evolved at U.S. defense-related facilities permits lifetime exposures similar to those permitted by a committed dose limitation system for radionuclides of intermediate effective half-life. Lifetime cancer risk for the maximally-exposed individual may be greater under the dose equivalent-limitation system due to the more rapid increase in committed dose equivalent which occurs with time compared to the increase under the ICRP system or its modified version.
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