Simultaneous measurements of radon, thoron and thoron progeny and induced cancer risk assessment in Djeno, Pointe-Noire, Republic of Congo.

In this study, the activity concentrations of radon (222Rn), thoron (220Rn) and thoron progeny were measured simultaneously in Djeno (Pointe-Noire, Republic of Congo) using RADUET detectors to evaluate the air quality and the radiological risks due to the inhalation of these radionuclides. Activity concentrations of radon progeny were calculated from those of radon. Indoor radon, thoron and progenies followed a lognormal distribution ranging between 20 and 40, 6 and 62, 8 and 17.6 and 0.4 and 19.6 Bq m-3 for radon, thoron, radon progeny and thoron progeny, respectively. Mean values for radon were lower than the worldwide values estimated by the United Nation Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), which are 40 Bq m-3 (arithmetic mean) and 45 Bq m-3 (geometric mean). Radon concentrations in the dwellings under study were below the World Health Organization and the International Commission on Radiological Protection recommended reference levels, which are, respectively, 100 and 300 Bq m-3. The mean concentration of thoron was twice the world average value of 10 Bq m-3 estimated by UNSCEAR. Thoron progeny mean concentration was sharply greater than the typical value (0.3 Bq m-3) for indoor atmosphere provided by UNSCEAR. Annual effective dose ranges were 0.40-0.87 mSv (arithmetic mean, 0.57 ± 0.11 mSv) for radon and 0.10-4.14 mSv (arithmetic mean, 0.55 ± 0.77 mSv) for thoron. The mean value for radon was lower than the value (1.15 mSv) estimated by UNSCEAR, while the mean value for thoron was five times higher than the UNSCEAR value (0.10 mSv). The study showed that the use of the typical equilibrium factor value given by UNSCEAR to compute effective dose led to an error above 80%. Finally, the results of this study showed that the excess relative risk of radon-induced cancer was low, below 2% for the population under 55 y. The results presented in the present study prove that the population of Djeno is exposed to a relatively low potential risk of radon- and thoron-induced cancer.

Car-borne survey and dose assessment from external radiation exposure in Bangka Island.

With a history of more than 200 years of tin mining, Bangka Island has brought along a byproduct of heavy minerals containing radionuclide elements. There are some concerns about this byproduct material contributing to natural radiation in the environment. In this study, a car-borne survey was conducted to accurately assess natural background radiation in Bangka Island. Indoor and outdoor ambient dose rates in 146 houses were also measured to assess the radiation dose from external exposure received by the public. Soil samples were collected and measured using a gamma spectroscopy system to evaluate the contributions of specific radionuclides to external terrestrial exposure. From 3790 measurement points during the car-borne survey, the highest ambient dose equivalent rate was 596 nSv h-1 measured in Muntok area, with a mean value of 101 nSv h-1 and a median value of 95 nSv h-1. The ambient dose equivalent rate distribution map showed a relatively higher value in the northern coastal area of the island, where the Pemali tin deposit is located. The annual effective dose received from external radiation in the 146 houses in Bangka Island ranged from 0.44 to 1.30 mSv year-1, with a median value of 0.66 mSv year-1. The soil contained a relatively high amount of thorium (232Th), which contributed 69% to external radiation exposure in Bangka Island.

Utility of Physical Examination Findings for Predicting Low-Back Pain in Adolescent Patients with Early-Stage Spondylolysis: A Retrospective Comparative Cohort Study.

INTRODUCTION: This study aimed to elucidate low-back pain (LBP) characteristics, i.e., its qualities, extent, and location, in patients with early-stage spondylolysis (ESS). METHODS: We recruited patients (≤18 years old) who presented with acute LBP lasting up to 1 month. Patients were divided into ESS and nonspecific LBP (NS-LBP) groups based on their magnetic resonance imaging findings; patients showing no pathological findings that might explain the cause of LBP were classified as NS-LBP. All patients were evaluated using the following tests: hyperextension and hyperflexion (pain provocation tests in a standing position), pain quality (sharp/dull), pain extent (fingertip-sized area/palm-sized area), and pain location (left and/or right pain in side [side]/central pain [center]). We have also compared outcomes between the ESS and NS-LBP groups in terms of gender and physical symptoms. RESULTS: Of 101 patients, 53 were determined to have ESS (ESS group: mean age: 14.3 years old; 43 males/10 females), whereas 48 had no pathological findings explaining the LBP origin [NS-LBP group (mean age, 14.4 years old; 31 males/17 females)]. Chi-squared test has identified gender (male), a negative result on hyperflexion test, pain extent (fingertip-sized area), and pain location (side) to be significantly associated with ESS. Among these, regression analysis revealed that male gender and LBP located on the side were significantly associated with ESS (p<0.05). CONCLUSIONS: Although the hyperextension test is generally considered useful for ESS, we demonstrated that its association is not deemed significant. Our results indicate that male gender, a negative result of the hyperflexion test, fingertip-sized pain area, and LBP on the side may be specific characteristics of ESS. Of these physical signs, male gender and LBP located on the side are characteristic factors suggesting ESS presence.

Japanese population dose from natural radiation.

The radiation doses from natural radiation sources in Japan are reviewed using the latest knowledge. The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) and the Nuclear Safety Research Association report the annual effective doses from cosmic rays, terrestrial radiation, inhalation, and ingestion as natural sources. In this paper, the total annual effective dose from cosmic-ray exposure is evaluated as 0.29 mSv. The arithmetic mean of the annual effective dose from external exposure to terrestrial radiation is 0.33 mSv for the Japanese population using the data of nationwide surveys by the National Institute of Radiological Sciences. Previously in Japan, although three different groups have conducted nationwide indoor radon surveys using passive-type radon monitors, to date only the Japan Chemical Analysis Center (JCAC) has performed a nationwide radon survey using a unified method for radon measurements conducted indoor, outdoor, and in the workplace. Consequently, the JCAC results are used for the annual effective dose from radon and that for radon inhalation is estimated as 0.50 mSv using a current dose conversion factor. In this paper, UNSCEAR values are used for the mean indoor and outdoor thoron-progeny concentrations, and the annual effective dose from thoron is reported as 0.09 mSv. Thus, the annual effective dose from radon and thoron inhalation is 0.59 mSv. From a JCAC large-scale survey of foodstuffs, the committed effective dose from the main radionuclides in dietary intake is 0.99 mSv. Finally, the Japanese population dose from natural radiation is given as 2.2 mSv, which is similar to the reported global average of 2.4 mSv.

Radiation dose due to radon and thoron progeny inhalation in high-level natural radiation areas of Kerala, India.

In order to evaluate internal exposure to radon and thoron, concentrations for radon, thoron, and thoron progeny were measured for 259 dwellings located in high background radiation areas (HBRAs, outdoor external dose: 3-5 mGy y-1) and low background radiation areas (control areas, outdoor external dose: 1 mGy y-1) in Karunagappally Taluk, Kerala, India. The measurements were conducted using passive-type radon-thoron detectors and thoron progeny detectors over two six-month measurement periods from June 2010 to June 2011. The results showed no major differences in radon and thoron progeny concentrations between the HBRAs and the control areas. The geometric mean of the annual effective dose due to radon and thoron was calculated as 0.10 and 0.44 mSv, respectively. The doses were small, but not negligible compared with the external dose in the two areas.

Long-term measurements of residential radon, thoron, and thoron progeny concentrations around the Chhatrapur placer deposit, a high background radiation area in Odisha, India.

The Chhatrapur placer deposit is found in a high background radiation area which has been recently identified on the southeastern coast of India. Previously, some geochemical studies of this area were carried out to assess external dose from radionuclides-bearing heavy mineral sands. In this study, radon, thoron and thoron progeny concentrations were measured in about 100 dwellings during three seasons (autumn-winter, summer, and rainy) in a 10- to 12-month period and annual doses due to inhalation of them were evaluated. The measurements were made by passive-type radon-thoron discriminative detectors and thoron progeny detectors in which solid state nuclear track detectors were deployed. The results show that radon and thoron concentrations differ by one order of magnitude depending on exposure periods, while thoron progeny concentration is nearly constant throughout the year. Since thorium-rich sand is distributed in the studied area, exposure to thoron is equal to, or exceeds, exposure to radon and is not negligible for dose evaluation. Based on the measurements, doses due to inhalation of radon and thoron are evaluated as 0.1-1.6 mSv y-1 and 0.2-3.8 mSv y-1, respectively. The total dose is 0.8-4.6 mSv y-1, which is the same order of magnitude as the worldwide value.

Radiation survey on Fukushima Medical University premises about four years after the Fukushima nuclear disaster.

This study was conducted on the Fukushima Medical University (FMU) premises (in Fukushima City, Fukushima Prefecture) about four years after the Fukushima Daiichi Nuclear Power Plant accident.　Its objectives were (1) to create a map of the ambient gamma dose rate (air-kerma rate) distribution, (2) to evaluate the air-kerma rate originating from natural radionuclides, and (3) to investigate the effects of snow cover on changes in the air-kerma rate.　This man-borne survey revealed that the air-kerma rate varies widely, ranging from 0.038 µGy h(－1) to 0.520 µGy h(－1), and is higher on grass than on the other investigated surface types, such as soil, asphalt, and bricks.　In this area, the mean air-kerma rate from natural radiation was evaluated to be 0.03 ± 0.01 µGy h(－1), which is close to 0.04 µGy h(－1), which was measured in central Fukushima City by a local authority.Furthermore, snowfall was found to reduce the air-kerma rate by 5%-30%.　This reduction was attributed to attenuation of the primary radiation while passing through the snow cover, and the measured contribution of scattered radiation to the air-kerma rate reduction was small.　The reduction rate was found to depend on the initial snow depth but to maintain a similar value for a couple of days, after the snow had partially melted and its depth had decreased.　Finally, analysis of the daily dose due to external exposure received on the FMU premises revealed that no further health effects due to chronic radiation exposure at this site are to be expected.

A pediatric case of multiple palisaded encapsulated neuromas of the palms and soles.

Palisaded encapsulated neuroma (PEN) usually presents as a solitary, skin-colored papule on the face in middle-aged adults. We present a rare pediatric case of multiple PEN of the palms and soles. DNA analysis of the RET proto-oncogene in our patient showed no mutations in exons 13, 15, and 16.

Clinical applications of basic research that shows reducing skin tension could prevent and treat abnormal scarring: the importance of fascial/subcutaneous tensile reduction sutures and flap surgery for keloid and hypertrophic scar reconstruction.

We use evidence-based algorithms to treat abnormal scarring, including keloids and hypertrophic scars (HSs). This involves a multimodal approach that employs traditional methods such as surgical removal, postoperative radiotherapy, corticosteroid injection, laser, and silicone gel sheets. As a result, the rate of abnormal scarring recurrence has decreased dramatically over the past 10 years. However, several problems remain to be solved. First, despite the optimization of a radiotherapy protocol, over 10% of cases who are treated with surgery and postoperative radiotherapy still recur in our facility. Second, the treatment options for cases with huge keloids are very limited. To address these problems, we performed basic research on the mechanisms that drive the formation of keloids and HSs. Extrapolation of these research observations to the clinic has led to the development of two treatment strategies that have reduced the rate of abnormal scar recurrence further and provided a means to remove large scars. Our finite element analysis of the mechanical force distribution around keloids revealed high skin tension at the keloid edges and lower tension in the keloid center. Moreover, when a sophisticated servo-controlled device was used to stretch wounded murine dorsal skin, it was observed that the stretched samples exhibited upregulated epidermal proliferation and angiogenesis, which are also observed in keloids and HSs. Real-time RT-PCR also revealed that growth factors and neuropeptides are more strongly expressed in cyclically stretched skin than in statically stretched skin. These findings support the well-established notion that mechanical forces on the skin strongly influence the cellular behavior that leads to scarring. These observations led us to focus on the importance of reducing skin tension when keloids/HSs are surgically removed to prevent their recurrence. Clinical trials revealed that subcutaneous/fascial tensile reduction sutures, which apply minimal tension on the dermis, are more effective in reducing recurrence than the three-layered sutures used by plastic surgeons. Moreover, we have found that by using skin flaps (e.g., perforator flaps and propeller flaps), which release tension on the wound, in combination with postoperative radiotherapy, huge keloids can be successfully treated.