Medical dosimetry in Hungary

Radiation exposure of medical staff during cardiological and radiological procedures was investigated. The exposure of medical staff is directly connected to patient exposure. The aim of this study was to determine the distribution of doses on uncovered part of body of medical staff using LiF thermoluminescent (TL) dosimeters in seven locations.Individual Kodak film dosimeters (as authorized dosimetry system) were used for the assessment of medical staff's effective dose. Results achieved on dose distribution measurements confirm that wearing only one film badge under the lead apron does not provide enough information on the personal dose.The value of estimated annual doses on eye lens and extremities (fingers) were in good correlation with international publications.     

The radioactivity of building materials

Summary Radiation exposure of the population can be increased appreciably by the use of building materials containing above-normal levels of naturally occurring radionuclides of terrestrial origin, as high as 1600 Bq^. kg^-1for ⁴⁰K in granites, 700 Bq^. kg^-1for ²²⁶Ra in phosphogypsum and 360 Bq^. kg^-1for ²³²Th in granites. In a 25-year survey including more than two hundreds of different materials were investigated. Of the materials normally used in the building industry, i.e., red clay bricks, cement of Portland Types I and II, concretes, gravels and sand, contain regular levels of the primordial radionuclides. The adsorbed dose rate in indoor air, in general, does not exceed the dose criterion of 80 nGy^. h^-1or 0.3 mSv^. y^-1for the effective dose. Granites and phosphogypsum are the highly radioactive materials for which the absorbed dose rate in indoor air becomes up to five times higher than the dose criterion. It is recommended to avoid the use of those materials without radioactivity control.     

Gamma radiation and radon levels in Mexico City dwellings

Gamma exposure rate and radon levels were measured in 75 single-family dwellings in Mexico City in order to correlate them with local environment. Radon monitoring was performed both indoors and outdoors using a continuous working level monitor for short-lived radon decay products; the gamma exposure rate was measured using CaSO₄: Dy+PTFE. The results obtained show a log-normal distribution. The mean indoor radon concentration is lower than 45 Bq/m³ and the mean indoor gamma exposure rate was 11.29 R/h.     

Background radiation study in Coimbatore city,Tamilnadu

The activity concentration and absorbed gamma dose rates due to primordial radionuclides (²³⁸U, ²³²Th and ⁴⁰K) have been determined for the soil of Coimbatore city using NaI(Tl) gamma-ray spectrometer. The average activity concentrations of ²³²Th, ²³⁸U and ⁴⁰K in the soil samples have been found to be 31.4 Bq·kg⁻¹, 12.8 Bq·kg⁻¹ and 698.0 Bq·kg⁻¹, respectively, which give the total gamma dose rate contribution of 56.4 nGy·h⁻¹. Grab sampling technique has been used to determine the indoor radon (²²²Rn) and thoron (²²⁰Rn) progeny levels in different dwellings in the city. The concentrations of radon and thoron progenies range from 0.4 to 10.4 and from 0.7 to 12.7 mWL with a mean value of 1.4 mWL and 3.1 mWL, respectively. The annual effective dose due to radon and thoron progeny has been found to be 0.14 mSv·y⁻¹.     

ISO radiation sterilization standards

This presentation provides an overview of the current status of the ISO radiation sterilization standards. The ISO standards are voluntary standards which detail both the validation and routine control of the sterilization process. ISO 11137 was approved in 1994 and published in 1995. When reviewing the standard you will note that less than 20% of the standard is devoted to requirements and the remainder is guidance on how to comply with the requirements.

Future standards developments in radiation sterilization are being focused on providing additional guidance. The guidance that is currently provided in informative annexes of ISO 11137 includes: device/packaging materials, dose setting methods, and dosimeters and dose measurement, currently, there are four Technical Reports being developed to provide additional guidance:

1. 1. AAMI Draft TIR, “Radiation Sterilization Material Qualification”

2. 2. ISO TR 13409-1996, “Sterilization of health care products — Radiation sterilization — Substantiation of 25 kGy as a sterilization dose for small or infrequent production batches”

3. 3. ISO Draft TR, “Sterilization of health care products — Radiation sterilization Selection of a sterilization dose for a single production batch” li]4. ISO Draft TR, “Sterilization of health care products — Radiation sterilization-Product Families, Plans for Sampling and Frequency of Dose Audits.”

     

Measurement of environmental gamma dose levels around Udupi district of coastal Karnataka,India

The outdoor and indoor environmental gamma dose rates in air have been measured in several parts of Udupi district, Karnataka, India using thermoluminescent dosimeters (TLDs). The outdoor annual gamma dose values varies in the range 0.49–1.17 mGy/year with mean 0.75 ± 0.18 mGy/year. Similarly indoor annual gamma dose varies in the range 0.51–1.10 mGy/year with mean 0.74 ± 0.13 mGy/year. The mean values of indoor and outdoor gamma dose rates were 84 and 86 nGy/h respectively with indoor to outdoor dose ratio of 1.02.     

Minimum Exposure Limits and Measured Relationships Between the Vitamin D,Erythema and International Commission on Non‐Ionizing Radiation Protection Solar Ultraviolet

The International Commission on Non‐Ionizing Radiation Protection (ICNIRP) has established guidelines for exposure to ultraviolet radiation in outdoor occupational settings. Spectrally weighted ICNIRP ultraviolet exposures received by the skin or eye in an 8 h period are limited to 30 J m^?2. In this study, the time required to reach the ICNIRP exposure limit was measured daily in 10 min intervals upon a horizontal plane at a subtropical Australian latitude over a full year and compared with the effective Vitamin D dose received to one‐quarter of the available skin surface area for all six Fitzpatrick skin types. The comparison of measured solar ultraviolet exposures for the full range of sky conditions in the 2009 measurement period, including a major September continental dust event, show a clear relationship between the weighted ICNIRP and the effective vitamin D dose. Our results show that the horizontal plane ICNIRP ultraviolet exposure may be used under these conditions to provide minimum guidelines for the healthy moderation of vitamin D, scalable to each of the six Fitzpatrick skin types.     

Monitoring of environmental radiation on the Spratly Islets in the South China Sea

The concentration of radionuclides in environmental samples and the environmental radiation level (including cosmic rays) was monitored on Spratly Islets in South China Sea prior to the commercial operation of nearby Chinese nuclear power plants. Samples of coral sand, sea food, vegetation, water, and accumulated fallout on the islet were obtained and measured for radioactivity. Except for some exposure originating from minute amounts of⁶⁰Co and¹³⁷Cs, the radiation background is mainly emitted from naturally occurring radionuclides. Radiation levels including beta, gamma, and neutron on the islet have also monitored. Gamma dose rates for outdoor exposure averaged approximately 0.09 Sv/h; the neutron dose rate was about 0.003 Sv/h. Automatic radiation surveillance and a routine sampling program on the Spratly Islets are viewed as essential to provide an early warning in the Far East in case of a nuclear emergency.     

Natural indoor gamma background in Coonoor environment of South India

Indoor natural radiation dose existing in dwellings of Coonoor have been estimated using thermoluminescent dosimeters. TLDs are displayed in indoors and are replaced after three-month period. The seasonal averages of the dose rate and the annual effective dose equivalent are calculated from the measured results. Geographical and seasonal variations as well as the differences between indoor to outdoor dose rates have also been studied. Very good correlation exists between the indoor dose rates measured by TLD and environmental radiation dosimeter with correlation coefficient of 0.91. The annual effective dose equivalent to the Coonoor population due to indoor gamma radiation was estimated to be 970 mSv/y for the period of 1997–1998.     

Quantification of radiation induced crosslinking in a commercial, toughened silicone rubber, TR55 by H MQ-NMR

Radiation induced degradation in a commercial, filled silicone composite has been studied by SPME/GC-MS, DMA, DSC, swelling, and multiple quantum NMR. Analysis of volatile and semi-volatile species indicates degradation via decomposition of the peroxide curing catalyst and radiation induced backbiting reactions. DMA, swelling, and spin-echo NMR analysis indicate an increase in crosslink density of near 100% upon exposure to a cumulative dose of 250 kGray. Analysis of the sol fraction via Charlesby-Pinner analysis indicates a ratio of chain scission to crosslinking yields of 0.38, consistent with the dominance of the crosslinking observed by DMA, swelling and spin-echo NMR and the chain scissioning reactions observed by MS analysis. Multiple quantum NMR has revealed a bimodal distribution of residual dipolar couplings near 1 krad/s and 5 krad/s in an approximately 90:10 ratio, consistent with bulk network chains and chains associated with the filler surface. Upon exposure to radiation, the mean 〈Ω_d〉 for both domains and the width of both domains increased. The MQ-NMR analysis provided increased insight into the effects of ionizing radiation on the network structure of silicone polymers.     

Investigation of radon and thoron concentrations in a landmark skyscraper in Tokyo

The temporal variation of the radon concentration, and the radon and thoron concentrations every 3 months for a year were measured using two types of devices in a landmark skyscraper, the Tokyo Metropolitan Government Daiichi Building. In the measurement of temporal variation of the radon concentration using a pulse type ionization chamber, the average radon concentration was 21 ± 13 Bq m^?3 (2–68 Bq m^?3). The measured indoor radon concentration had a strong relationship with the operation of the mechanical ventilation system and the activities of the office workers. The radon concentration also increased together with temperature. Other environmental parameters, such as air pressure and relative humidity, were not related to the radon concentration. In the long-term measurements using a passive radon and thoron discriminative monitor, no seasonal variation was observed. The annual average concentrations of radon and thoron were 16 ± 8 and 16 ± 7 Bq m^?3, respectively. There was also no relationship between the two concentrations. The annual average effective dose for office workers in this skyscraper was estimated to be 0.08 mSv y^?1 for 2000 working hours per year. When considering the indoor radon exposure received from their residential dwellings using the annual mean radon concentration indoors in Japan (15.5 Bq m^?3), the annual average effective dose was estimated to be 0.37 mSv y^?1. This value was 31 % of the worldwide average annual effective dose.     

Natural radioactivity and indoor radiation measurements in buildings and building materials in Gobichettipalayam town

Samples of natural and manufactured building materials used by the people of Gobichettipalayam town have been analyzed for ²²⁶Ra, ²³²Th and ⁴⁰K using gamma-ray spectrometry. Radium equivalent activity of the materials has been measured using the formula given by OECD and the geometric mean value of sand, clay and cements are found to be 53.53 Bq·kg⁻¹, 89.09 Bq·kg⁻¹ and 72.25 Bq·kg⁻¹, respectively. The radium equivalent activities obtained in the building materials are all well below the acceptable limit. The indoor gamma-dose has been measured using thermoluminescence dosimeters and it was found in the range of 1051.2–3946.0 μGy/year. The annual effective indoor gamma radiation dose to the people of Gobichettipalayam town has been found to be 0.8 mSv/y.     

Radon survey in office room and effective dose estimation for staff

This study aims to: (1) Acquire the radon level in closed office rooms, providing radon exposure data for preliminary health risk assessment of office-working population. (2) Pre-analyze the relationship between radon concentration and indoor temperature, relative humidity. (3) Estimate seasonal, annual and total radon effective dose for ordinary office-working population. The results show that the 24-h or 8-h average radon concentrations in closed office rooms were about 32.0 Bq/m³ and 29.5 Bq/m³ during detection period, and the estimated effective doses in office rooms calculated by using 24-h and 8-h average radon concentrations were all far below that in residential environment.

     

Radon and thoron concentrations in offices and dwellings of the Gunma prefecture, Japan

Summary Aone year survey of indoor radon and thoron concentrations was carried out in offices and dwellings of the Gunma prefecture, Japan. A passive integrating radon and thoron discriminative monitor was used in the survey. The annual mean radon concentration was 22±14 Bq ^. m^-3, and ranged from 12 to 93 Bq ^. m^-3 among the 56 surveyed rooms. Radon concentration in offices was generally higher than that in the dwellings, with the arithmetic averages of 29 and 17 Bq ^. m^-3, respectively. Radon concentrations were generally lower in the traditional Japanese wooden houses than those houses built with other building materials. Seasonal variation of indoor radon was also observed in this survey. Compared to summer and autumn, radon concentrations were generally higher in spring and winter. The mean value of thoron to radon ratio was estimated to be 1.3, higher values were observed in the dwellings than in the offices. The annual effective dose from the exposure to indoor radon was estimated to be 0.47 mSv after taking the occupancy factors of offices and dwellings into account.     

Radon,thoron and their progeny concentration variations in dwellings of Gogi region,Yadgir district of Karnataka,India

The radiation dose due to inhalation of radon, thoron and their progenies constitute a major part (50 %) of the total natural background dose received by a man. Thus measurement of indoor radon in dwellings is very important. In the present study, radon, thoron and their decay product measurements were carried out using passive detector systems, namely the pinholes dosimeters and Direct Radon (Thoron) progeny sensors. These measurements were carried out in indoor environments (different dwelling types) during January–April 2013 for 90 days, in the Gogi region. The time-averaged mean radon, thoron and decay product concentrations were found to be within the permissible UNSCEAR limits.     

Effect of natural gas usage on indoor radon levels

Effect of natural gas usage on indoor radon concentrations were investigated in dwellings in four counties of ?zmir municipality using LR-115 Type II cellulose nitrate films. The dwellings were separated two groups: natural gas user and non-user. Indoor radon levels were found higher in natural gas using dwellings. Also, indoor radon levels were evaluated in terms of concentrations and annual effective dose. Indoor radon concentrations were found between 22.8 and 707.8 Bq m^?3 and highest concentrations were determined in kitchen in third floor of Bornova dwellings. Indoor radon concentrations in kitchens were found higher than the living rooms. On the other hand, opposite results obtained for annual effective dose, because of very short occupancy period of the kitchens.     

Ultraviolet radiation exposure of children and adolescents in Durban,South Africa

The solar ultraviolet radiation (UVR) exposure of 30 children and adolescents in three age groups (4-6 years, 7-9 years and 13-14 years) was measured for 1 week in late summer (February-March) in Durban, South Africa, using UVR-sensitive polysulfone film badges (PSFB) attached to the lapel region of the body. The mean and median values for all ages over the study period were 2.0 and 1.2 standard erythemal dose (SED) units, respectively, where 1 SED = 100 J x m(-2). Individual PSFB doses were analyzed as a function of age, gender and behavior. No significant statistical differences were found between different age groups; however, there was a statistical difference between males and females, with males generally receiving higher PSFB doses. Subjects completed UVR exposure journals documenting their time outdoors, shade versus sun conditions, nature of their activities, clothing worn and their use of sunscreen for each day of the study. Activity patterns were noted as the most important factor influencing individual UVR dose. Ambient erythemal UVR was measured by a Yankee Environmental Systems UVB pyranometer, and a relationship between ambient UVR and individual UVR dose was derived. On average, subjects received a dose of 4.6% of the total daily erythemal UVR. Based on this factor, the potential dose of an individual over a full annual cycle was estimated. Accordingly, there were 139 days during the year when an individual with skin type I (light skin) would be likely to experience minimal erythema and 97 and 32 days for individuals with skin types II and III, respectively.     

Indoor radon measurement in Izmir Province,Turkey

In 2013, an extensive study was performed in a total of 117 locations in Izmir province and indoor radon levels were measured using the alpha track etch integrated method with LR-115 detectors. As the maps are more practical to interpret the results of radiological survey, the distributions of indoor ²²²Rn activities in four most densely populated districts of Izmir were mapped in detail. It is seen that the estimated average radon concentration level (210 Bq m^?3) determined in Izmir province was almost three times higher than the mean value for Turkey (81 Bq m^?3). Exposed annual effective dose equivalents for Izmir province were estimated in the range of 0.7 to 12.3 mSv year^?1 with a mean of 5.3 mSv year^?1. In this study, it is pointed out that indoor radon concentration was affected by the age of the building and height above the ground.     

Dose assessment from exposure to radon,thoron and their progeny concentrations in the dwellings of sub-mountainous region of Jammu & Kashmir,India

The present work deals with the assessment of annual inhalation dose due to exposure of indoor radon, thoron and their progeny concentrations in the villages situated in sub-mountainous region of Jammu & Kashmir, India. The distribution of the data and the homogeneity of medians among different seasons and dwellings were assessed with the Shapiro–Wilk test and the Mann–Whitney test. The estimated total annual inhalation dose in these villages varied from 0.5 to 1.9 mSv year^?1 which is less than the prescribed limit by ICRP (2008). Thus, the investigated area is safe from irradiation of radon, thoron and their progeny.     

Measurement of cosmic radiation dose to air crew connecting for a typical polar route flight

In order to compare cosmic radiation dose for air crew including pilot and flight attendant between polar route flight and non-polar route flight, a typical polar flight route that is from Beijing to New York was selected and compared with non-polar route. Optically stimulated luminescence dosimeter and track etch detector CR-39 were worn as personal dosimeters to measure the cosmic radiation dose to air crew. The mean annual effective dose for air crew from polar route and non-polar route was (5.79 ± 0.92) mSv/year and (2.14 ± 0.64) mSv/year, respectively. The effective dose per 1,000 flight hours for air crew was (3.10 ± 0.27) mSv/1,000 h and (2.21 ± 0.46) mSv/1,000 h, respectively. The result is analyzed by using SPSS 15.0 statistical software. There was significant difference between the two groups for both mean annual effective dose (t = 30.25, P < 0.05) and the effective dose per 1,000 flight hours (t = 7.60, P < 0.05). The dose to pilot was higher than that of flight attendant for both polar route and non-polar route, and there was significant difference between them, for polar route (t = 7.96, P < 0.05), for non-polar route (t = 4.70, P < 0.05). The effective dose from cosmic radiation to air crew of polar route was higher than that of non-polar route, however, it did not exceed 20 mSv/year, which is the limit on cosmic radiation exposure set by many countries in the world.