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A modified Lucas cell for leakage measurement from encapsulated radium sources.

A new method to determine the leakage rate from encapsulated radium sources is proposed. The method is based on the principle of enclosing the source to be tested in a hermetically sealed container and measuring the radon radioactivity growth in the container as a function of time. A cylindrical modified Lucas cell, designed and built in our laboratory, is used for measuring the radon which are done by ZnS(Ag) alpha scintillation counting and can be easily compared with existing standard for leak tests. Results obtained show the applicability of the method for leak testing for radon leakage from sealed radium sources.

Kinetics↗

Radium-228 determination of natural waters via concentration on manganese dioxide and separation using Diphonix ion exchange resin.

The objective of this work was to establish a new procedure for 228Ra determination of natural waters via preconcentration of radium on MnO2 and separation of its daughter, 228Ac, using Diphonix ion exchange resin. Following removal of potential interferences via passage through an initial Diphonix Resin column, the first daughter of 228Ra, 228Ac, is isolated by chromatographic separation via a second Diphonix column. A holding time of > 30 h for 228Ac ingrowth in between the two column separations ensures secular equilibrium. Barium-133 is used as a yield tracer. Actinium-228 is eluted from the second Diphonix Resin with 5 ml 1M 1-Hydroxyethane-1,1-diphosphonic acid (HEDPA) and quantified by addition of scintillation cocktail and LSC counting. Radium (and 133Ba) from the load and rinse solutions from the 2nd Diphonix column may be prepared for alpha spectrometry (for determination of 223Ra, 224Ra, and 226Ra) by BaSO4 microprecipitation and filtration. Decontamination tests indicate that U, Th, and Ra series nuclides do not interfere with these measurements, although high contents of 90Sr (90Y) require additional treatment for accurate measurement of 228Ra. Addition of stable Sr as a "hold back" carrier during the initial MnO2 preconcentration step was shown to remove most 90Sr interference.

Chromatography, Ion Exchange↗

Measurement of 224Ra uptake in a fern actively accumulating radium.

A method is proposed for determining the level of 224Ra in plant samples by measuring its descendant nuclide 212Pb at 239 keV by gamma-ray spectrometry. Variations of 224Ra and 212Pb over time during sample preparation and counting were delineated prior to gamma-ray measurement. The 224Ra concentrations in plant samples were measured by their direct uptake from soil, which could be determined and distinguished from that resulting from decay of 228Th inside the plants. We propose that a field-growing Dicranopteris linearis, which actively accumulates radium, can be used as an indicator of the nutritional transportation and metabolic rate of radium and other alkaline earth elements. We investigated the influence of rainfall on 224Ra concentrations in fronds of D. linearis and the corresponding uptake rates. 224Ra could serve as a natural tracer of growth in plants over a several days. Its presence and content in plants implies a temporal mineral metabolic rate, which can provide useful information for plant physiological and environmental investigations.

Ferns↗

Can barium and strontium be used as tracers for radium in soil-plant transfer studies?

Radium is one of the prominent potential contaminants linked with industries extracting or processing material containing naturally occurring radionuclides. In this study we investigate if 133Ba and 85Sr can be used as tracers for predicting 226Ra soil-to-plant transfer. Three soil types were artificially contaminated with these radionuclides and transfer to ryegrass and clover was studied. Barium is considered a better tracer for radium than strontium, given the significant linear correlation found between the Ra and Ba-TF. For strontium, no such correlation was found. The relationship between soil characteristics and transfer factors was investigated. Cation exchange capacity, exchangeable Ca+Mg content and soil pH did not seem to influence Ra, Ba or Sr uptake in any clear way. A significant relation (negative power function) was found between the bivalent (Ca+Mg) concentration in the soil solution and the Ra-TF. A similar dependency was found for the Sr and Ba-TF, although less significant.

Barium↗

Radium equivalent activity concentrations in concrete building blocks in eight cities in Southwestern Nigeria.

The radioactivity concentrations of (226)Ra, (232)Th and (40)K were measured by using gamma ray spectroscopy in 130 concrete building blocks collected from block making sites in eight cities in Southwestern Nigeria. The results were used to compute the radium equivalent activity concentration for each city. The values of the concentrations of the primordial radionuclides varied widely within each city and among the cities. The weighted means for the cities range between 13.3 and 18.4, 28.2 and 71.6, and 176.2 and 336.8 Bq/kg for (226)Ra, (232)Th and (40)K, respectively. The city weighted means of radium equivalent activity concentrations for the eight cities range from 81 to 145 with a mean of 101 Bq/kg. The maximum for external hazard index was determined as 0.39. All the values are within the safety limits recommended by UNSCEAR [United Nations Scientific Committee on the Effects of Atomic Radiation 1982. Report to the General Assembly, with annexes. New York, United Nations.].

Cities↗

Results of intracavitary radium treatment for adenocarcinoma of the body of the uterus.

Between 1965 and 1970, 160 inoperable patients with adenocarcinoma of the endometrium were treated using intracavitary radium alone. Patients were given either two insertions (7500 cGy stated dose over 10 days), or one insertion (5000 cGy stated dose over 4 days) depending on their general condition. The FIGO stage and histological degree of differentiation had a significant influence on survival. Most patients had Stage 1 disease; 5-year and 10-year corrected survival for those having two insertions was 73% and 62% respectively, compared with 58% and 34% respectively for those having a single insertion (p less than 0.015). The primary tumour control rate was greater using two insertions (77%) than with a single insertion (67%). Treatment morbidity was low. In this selected group of patients, intracavitary radium using a central intrauterine line source and vaginal ovoids produced results comparable with other reported radiotherapy techniques.

Adenocarcinoma↗

Determination of 222Rn emanation fraction and diffusion coefficient in concrete using accumulation chambers and the influence of humidity and radium distribution.

In this paper we present a laboratory method for the determination of diffusion coefficient, D, as well as the 222Rn emanation fraction, f, in concrete core samples. It is based either on the analyses of the growth curves of the radon in the air volume surrounding a sample enclosed in an accumulation chamber (Lucas cell or RADIM device) or using the charcoal adsorption method. Samples used have a special geometry allowing the assumption of a one-dimensional diffusion of radon in material. Radium was enhanced in the concrete samples by adding radium bromide solution or uranium ore. A strong dependence of the emanation fraction on the enhancing method was observed. For the sample enhanced with uranium ore the specific exhalation rate was about ten times smaller. A marked dependence of radon exhalation on the water content was also observed.

Air Pollutants, Radioactive↗

A rapid method for alpha-spectrometric analysis of radium isotopes in natural waters using ion-selective membrane technology.

An alpha-spectrometric method for the rapid determination of radium isotopes (223Ra, 224Ra and 226Ra) in environmental samples is presented. Using Empore Radium Rad Disks complete separation of the target radionuclides is achieved. The high selectivity of these Rad Disks allows the straightforward use of 225Ra as yield tracer. Chemical yield is up to 92 +/- 9%. The chemical procedure can be accomplished within 5h. Alpha-sources show energy resolution in the range of typically 26-40 keV (FWHM). Despite minimal thickness of the sources no significant radon (Rn) losses can be observed.

Alpha Particles↗

Preconcentration of radium isotopes from natural waters using MnO2 Resin.

We have characterized "MnO2 Resin," a new resin developed by the PG Research Foundation, for radium adsorption over wide ranges of pH, reaction times and salt concentrations. We show that the sorption of 133Ba (used as a proxy for Ra) is highly dependent on pH with the most useful range from pH 4 to 8. The surface layers of the Mn oxides apparently become more positively charged under acidic conditions (below pH 4), which prevents diffusion of positively charged alkaline earth species (e.g. Ba2+, Ra2+) into the sorption sites. Adsorption at higher pH is thought to be inhibited because of carbonate complexation. We found that the sorption characteristics for radium onto MnO2 Resin are especially favorable for low-salinity waters but the sorption is still very satisfactory for highly salted solutions (KD=2.8x10(4) in both cases) but with slower kinetics. For analytical purposes, both column and pump experiments showed high recoveries with no measurable discrimination between Ra and Ba regardless of flow rates in fresh water. Seawater tests showed that recoveries of Ra and Ba are lower than fresh water at elevated flow rates with Ra adsorption higher than Ba at flow rates above 10 ml/min.

Barium Radioisotopes↗

An analysis of bone and head sinus cancers in radium dial painters using a two-mutation carcinogenesis model.

Bone and head sinus cancer incidence after ingestion of 226Ra and 228Ra by radium dial painters is analysed using a two-mutation clonal expansion model for radiation carcinogenesis, taking into account the retention and radiation patterns of these nuclides in the body. The best fit is obtained for compact bone retention and efficient diffusion of 222Rn to the bone cavities and radiation action on both mutation rates of the cancer model, as found in a similar analysis of bone sarcomas after 226Ra injection in beagles. The model parameters of the best fit are consistent with cellular radiobiological data and a previous analysis of lung cancer in uranium miners. Due to the low background incidence of bone and head sinus cancer, the resulting dose-effect relationships for these cancers are linear-quadratic with radium ingestion and alpha radiation dose. These results do not support a threshold dose concept, but the risks at low doses calculated by the model come out to about a factor 10 lower than using a linear extrapolation of the data to low doses, a procedure currently applied by ICRP and EPA. Furthermore, the model results indicate radiation risks at low doses to be related with background cancer incidence between relative and absolute radiation risk projections. The results, which are dependent on the model assumptions, might be more generally applicable for bone seekers and will therefore need further study to arrive at better radiation risk estimations.

Adult↗

Cancer incidence after childhood nasopharyngeal radium irradiation: a follow-up study in Washington County, Maryland.

A population from a hearing clinic in Washington County, Maryland, in 1943-1960 was followed to assess the risk of developing neoplasms from radium treatment of the nasopharynx for adenoid hypertrophy. Of the 2,925 subjects who attended the clinic, 904 received radium treatment. A nonconcurrent prospective study compared the cancer incidence among the irradiated persons with that among persons with other treatments. Seven brain tumor cases (three malignant and four benign) were identified in the irradiated group versus none in the nonirradiated group (relative risk = 14.8, 95% confidence interval: 0.76, 286.3). A nonsignificant excess risk of thyroid cancer was detected in the irradiated group based on two cases in the exposed group and one case in the nonexposed group (relative risk = 4.2, 95% confidence interval: 0.38, 46.6). Decreased risks of breast cancer, female genital cancers, and prostate cancer were observed among the irradiated individuals, although these deficits were not statistically significant individually. The decreased risk of sex hormone-related cancers in the irradiated group suggests possible radiation damage to the pituitary, with consequent reduction in pituitary hormone output and alterations in sexual and other hormonal development in early life. This hypothesis needs further evaluation.

Adenoids↗

Life span dynamics of intra-skeletal radionuclide distribution in radium-injected beagles.

The distribution of 226Ra activity among the bone groups of the skeleton has been measured as a function of time after exposure for 12 beagles. The dogs were given 8 semi-monthly injections of radium totalling 0.37 microCi/kg, 1.11 microCi/kg, or 3.33 microCi/kg between the ages of 435 and 535 days. They were then sacrificed from 27 to 2764 days after the last injection. The fractional contribution of individual bone groups to the initial skeletal radioactivity distribution changed during the time of this study; the maximum decrease was a factor of 0.54 and the maximum increase was a factor of 1.58. Using a partitioned clearance model, the whole-body retention function characteristic of beagles exposed to radium levels less than or equal to 3.33 microCi/kg was partitioned into two functions representative of cancellous and compact bone. The functions were incorporated into a mathematical description of the 226Ra distribution data in a manner that provides estimates for the fraction of cancellous and compact bone in each skeletal component. Comparison of dosimetric estimates and site-specific tumor occurrence for these beagles revealed an apparent 90-fold variation of dose-response among the bone groups studied.

Animals↗

Comparison of radiological changes in humans and beagles with skeletal deposits of radium.

At the Laboratory for Energy-related Health Research at the University of California, Davis, semimonthly injections of 226Ra were given to a group of beagle dogs, and periodic skeletal radiography followed, as well as histological studies of the bones. At the Center for Human Radiobiology (Argonne National Laboratory, Massachusetts Institute of Technology, New Jersey Radium Research Project) measurements were made of radium body content in 2259 occupationally or iatrogenically exposed persons. Of these, 1768 had skeletal radiography (one or more times). In humans, the radiographic changes were, in decreasing order of frequency, osteolytic cortical and cancellous bone destruction, bone sclerosis, pathological fracture, and avascular necrosis of bone. In beagles, osteolytic destruction and pathological fractures were common, avascular necrosis was not observed, but there was frequently cortical thickening and new-bone formation in cancellous bone. In both population groups, there was a high incidence of bone sarcoma. In the beagles, one high-dosage group numbering 38 dogs had 49 malignant bone tumors. Among the 2259 measured persons, there were 60 who had bone sarcoma, and 29 who had cancer of the mastoids or paranasal sinuses. No significant skeletal effects have been diagnosed radiologically in persons with systemic intakes of 226Ra or 228Ra below about 10 mu Ci or with skeletal doses below about 100 rad. In humans, the lowest skeletal dose at which a bone sarcoma has been diagnosed is 890 rad, and the lowest intake associated with a bone sarcoma is 96 mu Ci 226Ra or about 1.7 mu Ci per kg body weight.

Animals↗

Cervical-vaginal bacterial flora in patients with cervical carcinoma treated with irradiation and febrile morbidity during intracavitary radium therapy.

The cervical-vaginal bacterial flora of 57 patients with invasive carcinoma of the cervix were found to be identical to those reported in studies of different population groups, except for a lower frequency of anaerobic bacteria. Radiation suppressed significantly both the aerobic and anaerobic bacteria. Following 4,000 rads of external irradiation, 47.4% of the cervical cultures were bacteriologically sterile. During the first and second radium treatment, 21% and 25.5% of the patients respectively developed fever of 38 degrees C or more, the cause of which could not definitely be established. The significance of fever during radium treatment is discussed.

Adult↗

Marie and Pierre Curie and radium: history, mystery, and discovery.

Commencing with Marie Curie's early life in Poland and the discovery of radium in the rue l'Homond "shed" in Paris in 1898, this paper includes some little known facts. It ends with some unusual uses of and claims for radium, and finally, because Medical Physics is an American journal, details are included of Marie Curie's two visits to the USA.

France↗

Bone cancer from radium: canine dose response explains data for mice and humans.

Analysis of lifetime studies of 243 beagles with skeletal burdens of radium-226 shows that the distribution of bone cancers clusters about a linear function of the logarithms of radiation dose rate to the skeleton and time from exposure until death. Similar relations displaced by species-dependent response ratios also provide satisfactory descriptions of the reported data on deaths from primary bone cancers in people and mice exposed to radium-226. The median cumulative doses (or times) leading to death from bone tumors are 2.9 times larger for dogs than for mice and 3.6 times larger for people than for dogs. These response ratios are well correlated with the normal life expectancies. The cumulative radiation dose required to give significant risk of bone cancer is found to be much less at lower dose rates than at higher rates, but the time required for the tumors to be manifested is longer. At low dose rates, this time exceeds the normal life-span and appears as a practical threshold, which for bone cancer is estimated to occur at an average cumulative radiation dose to the skeleton of about 50 to 110 rads for the three species.

Animals↗

Analysis of dose, dose-rate and treatment time in the production of injuries by radium treatment for cancer of the uterine cervix.

A retrospective study has been made of 15 patients who had developed severe complications to the bladder, rectum and ureters after radiation therapy for carcinoma of the cervix. Comprehensive dose distribution in the pelvis were calculated with computer assistance to visualize how the normal organs had been irradiated. The risk of normal tissue injury was analysed graphically with respect to the maximum radium dose, dose-rate and irradiation time. The two groups of data representing the injured and non-injured organs separate much better in a dose-rate versus dose plot than in a conventional Strandqvist type dose-time plot. This implies that in radium therapy, the dose-rate rather than the treatment time, is the important parameter in modifying the risk of normal tissue injury. Our results show a good separation of injured from non-injured cases only when the maximum values of dose and dose-rate were used. This suggests that clinically significant injury may develop from relatively small regions of high dose and dose-rate. Since the dose-rate varies from point to point in the pelvis (unlike treatment time), comprehensive determinations of dose-rate distributions are required in order to locate the sites of potential injuries.

Dose-Response Relationship, Radiation↗