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PubMed1998

[Automated procedures for radiation protection and quality controls in conventional diagnostic radiology].

To comply with regulations on radiation protection and quality controls is a difficult task when operating in large hospitals. This leads to the need of defining more efficient protocols and of making procedures as automated as possible. The procedure described in this paper is based on a multimeter controlled by a portable PC, and on a spreadsheet program for data processing. Multimeter data are automatically imported and processed, in order to assess the compliance of measured parameters with the reference regulations (IEC recommendations, radiation safety rules, etc.). The spreadsheet is permanently linked to a data base. It is therefore possible to perform the controls and to store the corresponding results in a shorter time (one hour per machine, approximately). By using a properly chosen quality index, monitoring the efficiency of the diagnostic equipment is also possible, which allows to prevent the onset of severe failures.

Computers↗
PubMed1985

Radiation carcinogenesis in experimental animals and its implications for radiation protection.

Cancer induction is generally considered to be the most important somatic effect of low doses of ionizing radiation. It is therefore of great concern to assess the quantitative cancer risk of exposure to radiations of different quality and to obtain information on the dose-response relationships for carcinogenesis. Tissues in the human with a high sensitivity for cancer induction include the bone marrow, the lung, the thyroid and the breast in women. If the revised dosimetry estimates for the Japanese survivors of the atomic bomb explosions are correct, there is no useful data base left to derive r.b.e. values for human carcinogenesis. As a consequence, it will be necessary to rely on results obtained in biological systems, including experimental animals, for these estimates. With respect to radiation protection, the following aspects of experimental studies on radiation carcinogenesis are of relevance: Assessment of the nature of dose-response relationships. Determination of the relative biological effectiveness of radiations of different quality. Effects of fractionation or protraction of the dose on tumour development. For the analysis of tumour data in animals, specific approaches have to be applied which correct for competing risks. These methods include actuarial estimates, non-parametric models and analytical models. The dose-response curves for radiation-induced cancers in different tissues vary in shape. This is exemplified by studies on myeloid leukaemia in mice and mammary neoplasms in different rat strains. The results on radiation carcinogenesis in animal models clearly indicate that the highest r.b.e. values are observed for neutrons with energies between 0.5 and 1 MeV. On the basis of such results it might be concluded that the maximum quality factor of 10 for neutrons should be increased. Based on current evidence, an increase by a factor of 2 to 3 seems more realistic than a tenfold rise. The diversity of dose-response relationships point to different mechanisms involved in the induction of different tumours in various species and even in different strains of the same species.

Adenocarcinoma↗
PubMed2005

Antioxidant activity of fractionated extracts of rhizomes of high-altitude Podophyllum hexandrum: role in radiation protection.

Whole extract of rhizomes of Podophyllum hexandrum has been reported earlier by our group to render whole-body radioprotection. High-altitude P. hexandrum (HAPH) was therefore fractionated using solvents of varying polarity (non-polar to polar) and the different fractions were designated as, n-hexane (HE), chloroform (CE), alcohol (AE), hydro-alcohol (HA) and water (WE). The total polyphenolic content (mg% of quercetin) was determined spectrophotometrically, while. The major constituents present in each fraction were identified and characterized using LC-APCI/MS/MS. In vitro screening of the individual fractions, rich in polyphenols and lignans, revealed several bioactivities of direct relevance to radioprotection e.g. metal-chelation activity, antioxidant activity, DNA protection, inhibition of radiation (250 Gy) and iron/ascorbate-induced lipid peroxidation (LPO). CE exhibited maximum protection to plasmid (pBR322) DNA in the plasmid relaxation assay (68.09% of SC form retention). It also showed maximal metal chelation activity (41.59%), evaluated using 2,2'-bipyridyl assay, followed by AE (31.25%), which exhibited maximum antioxidant potential (lowest absorption unit value: 0.0389 +/- 0.00717) in the reducing power assay. AE also maximally inhibited iron/ascorbate-induced and radiation-induced LPO (99.76 and 92.249%, respectively, at 2000 microg/ml) in mouse liver homogenate. Under conditions of combined stress (radiation (250 Gy) + iron/ascorbate), at a concentration of 2000 microg/ml, HA exhibited higher percentage of inhibition (93.05%) of LPO activity. HA was found to be effective in significantly (p < 0.05) lowering LPO activity over a wide range of concentrations as compared to AE. The present comparative study indicated that alcoholic (AE) and hydro-alcoholic (HA) fractions are the most promising fractions, which can effectively tackle radiation-induced oxidative stress.

Animals↗
PubMed2003

Analysis of occupational doses of workers on the dose registry of the Federal Radiation Protection Service in 2000 and 2001.

In 2000 and 2001 about 279 and 221 radiation workers, respectively, were monitored by the Federal Radiation Protection Service, University of Ibadan, in Nigeria. The distribution of the occupational doses shows that the majority of workers received doses below 4 mSv in each of the two years. The radiation workers in the two years are classified into two occupational categories: medicine and industry. The mean annual effective doses, collective doses and the collective dose distribution ratios for workers in each category and the entire monitored workers were calculated. The mean annual effective doses were compared with their corresponding worldwide values quoted by UNSCEAR. In each of the two years, a few workers in industry received doses higher than 50 mSv. The collective dose distribution ratio was found to be about 0.49, which is very close to the highest value of 0.5 in the range of values considered by UNSCEAR as normal for this parameter. This suggests that extra measures have to be taken, particularly in industry, to ensure that the proportion of workers at risk does not go outside this normal range. The occupational doses were also modelled by both the log-normal and Weibull distributions. Both distributions were found to describe the data in almost the same way.

Adult↗
PubMed1997

Radiation protection--lessons from the past.

This is a historical review of selected events in radiation protection of medical relevance since the discovery of X-rays. The report concentrates on the period 1895-1970. Key points were difficulty of measuring dose, rapid dissemination of the use of radiation for all sorts of illness, and regulation by professional bodies rather than by legislation. Both World Wars saw a huge expansion in the use of ionizing radiation, but the second war prevented international collaboration, which had begun formally in 1925. Early radiation deaths, and nuclear accidents have caused concerns about radiation safety, and although dose limits have been successively reduced, these concerns have not been overcome. Since the Second World War radiation safety has been subject to more and more legislation although professional bodies still have an important advisory role. Development of the main radiation safety committees both in the UK, US and internationally is described with emphasis on the particular role of the British Institute of Radiology.

History, 19th Century↗
PubMed2002

Radiation protection of people and the environment: developing a common approach.

The problem with the current ICRP system of radiation protection, particularly for regulators, is that it fails to differentiate between the application of justification and optimisation to people in the circumstances of medical care or as part of a workforce, compared with their application to members of the general public in an environmental setting; plus the fact that it also fails to address the issue of potential impacts on the rest of the environment in any meaningful way. But if these deficiencies are to be addressed, it will be essential to consider how protection of both people and the living environment can be achieved within a broad philosophical framework, using complementary approaches, based on the same underlying scientific knowledge. This paper briefly examines some of these issues, and offers some suggestions for developing a common, or even a combined, approach. It draws upon recent suggestions made by the ICRP itself with regard to radiological protection, plus current activities-on several fronts-to provide an explicit basis for environmental protection.

Environment↗
PubMed1981

Antihistamine provides sex-specific radiation protection.

Rats suffer an early transient performance decrement immediately after a sufficiently large dose of ionizing radiation. However, it has been shown that males experience a more severe incapacitation than females. This sex difference has been attributed to the low estrogen levels in the male. In support of this notion, supplemental estrogens in castrated male rats have produced less-severe performance decrements post-irradiation. Antihistamines have also previously been shown to alleviate radiation's effect on behavior. The present study revealed that antihistamines are only effective in altering the behavioral incapacitation of sexually intact male subjects. This contrasts with previous work which indicates that estrogens can only benefit gonadectomized rats. These findings suggest that different mechanisms may underly antihistamine and estrogen radiation protection.

Animals↗
PubMedDate not supplied

Radiation protection in radiologic technology: apathy versus active involvement.

The lack of active participation in radiation protection is a serious problem in Radiologic Technology today. Underlying the problem is professional apathy. An overview of the historical changes, as well as various recent developments in radiology, accentuate the importance of necessary changes in technologists' attitudes and activities.

Attitude↗
PubMed1986

Radiation protection during treatment of children with 131I-meta-iodobenzylguanidine.

This paper describes the radiation protection procedures that were used in caring for three children treated with therapeutic amounts of 131I-meta-iodobenzylguanidine. Since it was not possible to leave a child alone in a shielded room for several days, the presence of one parent was requested during the treatment. The dose equivalent to the parent was kept to an acceptable level of approximately 1 mSv. This dose equivalent was almost completely due to external radiation since blocking of the parent's thyroid led to a negligible dose equivalent from internal contamination.

3-Iodobenzylguanidine↗
PubMed2003

Improved radiation protection of the thyroid gland with thyroxine, methimazole, and potassium iodide during diagnostic and therapeutic use of radiolabeled metaiodobenzylguanidine in children with neuroblastoma.

BACKGROUND: During radiolabeled metaiodobenzylguanidine (MIBG) administration in children with neuroblastoma, the thyroid is protected from (123/131)I uptake by potassium iodide. Despite this protection, up to 64% of patients develop thyroid dysfunction. The authors introduce a new method of radiation protection for the thyroid gland. METHODS: In a prospective cohort study, 34 children with neuroblastoma who received MIBG were given thyroxine, methimazole, and potassium iodide for protection of the thyroid gland. Protection started 1 day before the start of diagnostic 123I-MIBG and was continued until 4 weeks after the last therapeutic 131I-MIBG dose. Follow-up measurements were performed every 3 months after the protection was stopped. Visualization of the thyroid on MIBG images was reviewed by three nuclear medicine physicians. Results were compared with a historic control group of children who had received potassium iodide for thyroid protection during MIBG administration. RESULTS: After a mean follow-up of 19 months, there were 23 evaluable patients. Thyroid function was normal in 86% of survivors compared with 44% of children in the historic control group (P=0.011; Pearson chi-square test). Scintigraphic visualization of the thyroid diminished substantially after the new protection (21.5% vs. 5.3%, respectively; P=0.000). CONCLUSIONS: The results of the current study indicate that compared with potassium iodide alone, combined thyroxine, methimazole, and potassium iodide protect the thyroid more effectively against radiation damage from (123/131)I during diagnostic and therapeutic MIBG administration in children with neuroblastoma.

3-Iodobenzylguanidine↗