Makoto Miyazaki

Internal radiocesium contamination of adults and children in Fukushima 7 to 20 months after the Fukushima NPP accident as measured by extensive whole-body-counter surveys

The Fukushima Dai-ichi NPP accident contaminated the soil of densely-populated regions in Fukushima Prefecture with radioactive cesium, which poses significant risks of internal and external exposure to the residents. If we apply the knowledge of post-Chernobyl accident studies, internal exposures in excess of a few mSv/y would be expected to be frequent in Fukushima. Extensive whole-body-counter surveys (n = 32,811) carried out at the Hirata Central Hospital between October, 2011 and November, 2012, however show that the internal exposure levels of residents are much lower than estimated. In particular, the first sampling-bias-free assessment of the internal exposure of children in the town of Miharu, Fukushima, shows that the 137Cs body burdens of all children (n = 1,383, ages 6–15, covering 95% of children enrolled in town-operated schools) were below the detection limit of 300 Bq/body in the fall of 2012. These results are not conclusive for the prefecture as a whole, but are consistent with results obtained from other municipalities in the prefecture, and with prefectural data.

Whole-body counter surveys of over 2700 babies and small children in and around Fukushima Prefecture 33 to 49 months after the Fukushima Daiichi NPP accident

BABYSCAN, a whole-body counter (WBC) for small children was developed in 2013, and units have been installed at three hospitals in Fukushima Prefecture. Between December, 2013 and March, 2015, 2707 children between the ages of 0 and 11 have been scanned, and none had detectable levels of radioactive cesium. The minimum detectable activities (MDAs) for 137Cs were ≤3.5 Bq kg−1 for ages 0–1, decreasing to ≤2 Bq kg−1 for ages 10–11. Including the 134Cs contribution, these translate to a maximum committed effective dose of ∼16 µSv y−1 even for newborn babies, and therefore the internal exposure risks can be considered negligibly small. Analysis of the questionnaire filled out by the parents of the scanned children regarding their families’ food and water consumption revealed that the majority of children residing in the town of Miharu regularly consume local or home-grown rice and vegetables, while in Minamisoma, a majority avoid tap water and produce from Fukushima. The data show, however, no correlation between consumption of locally produced food and water and the children’s body burdens.

Individual external dose monitoring of all citizens of Date City by passive dosimeter 5 to 51 months after the Fukushima NPP accident (series): 1. Comparison of individual dose with ambient dose rate monitored by aircraft surveys.

We are issuing an Expression of Concern to raise awareness of a potential problem in this article:nnIt has been brought to our attention that some of the data used in the study reported in this article potentially were without appropriate consent. We have further been advised that this is currently under investigation. If required, the publication record will be corrected as soon as possible.Date (date) City in Fukushima Prefecture has conducted a population-wide individual dose monitoring program after the Fukushima Daiichi Nuclear Power Plant Accident, which provides a unique and comprehensive data set of the individual doses of citizens. The purpose of this paper, the first in the series, is to establish a method for estimating effective doses based on the available ambient dose rate survey data. We thus examined the relationship between the individual external doses and the corresponding ambient doses assessed from airborne surveys. The results show that the individual doses were about 0.15 times the ambient doses, the coefficient of 0.15 being a factor of 4 smaller than the value employed by the Japanese government, throughout the period of the airborne surveys used. The method obtained in this study could aid in the prediction of individual doses in the early phase of future radiological accidents involving large-scale contamination.

Measurement of internal radiation exposure among decontamination workers in villages near the crippled Fukushima Daiichi Nuclear Power Plant.

AbstractDecontamination workers may face a high risk of exposure to internal irradiation through inhalation during decontamination activities; there is, however, little previous research on the levels of internal contamination during decontamination procedures. The authors reviewed the medical records, including whole body counter measurements, of decontamination workers in villages near the crippled Fukushima Daiichi Nuclear Power Plant to assess their levels of internal radiation exposure. In total, 83 decontamination workers were enrolled in this study. They were regularly engaged in decontamination activities in highly contaminated areas where surface 137Cs deposition density was over 100 kBq m−2. The present study showed low levels of internal exposure among the decontamination workers near the Fukushima Daiichi nuclear plant. The cesium burdens of all the decontamination workers were below detection limits. They had reported no acute health problems. The resuspension of radioactive materials may cause minimal internal contamination during decontamination activities.

Comprehensive whole-body counter surveys of Miharu-town school children for three consecutive years after the Fukushima NPP accident

Comprehensive whole-body counter surveys covering over 93% of the school children between the ages of 6 and 15 in Miharu town, Fukushima Prefecture, have been conducted for three consecutive years, in 2011, 2012 and 2013. Although the results of a questionnaire indicate that approximately 60% of the children have been regularly eating local or home-grown rice, in 2012 and 2013 no child was found to exceed the 137Cs detection limit of 300 Bq/body.

After Fukushima: Creating a dialogue.

Five years have passed since the accident at the Fukushima Daiichi Nuclear Power Plant. Although the additional exposure doses resulting from the accident were extremely low ([ 1 ][1]), it was difficult to dispel residents fear of radiation exposure (“Epidemic of fear,” D. Normile, News Feature, 4 March, p. [1022][2]) and other health issues. To address their concerns, we and others have provided a variety of services to increase understanding between residents and medical professionals.nnWe have held more than 500 general health consultations, which connect Fukushima residents with health experts from universities. The experts discuss individual residents health concerns and symptoms privately and then help coordinate integrated care to promote health and prevent disease. Through these social services, we aim to help dispel apprehensions among the evacuees and residents ([ 2 ][3]).nnOther local medical professionals and experts have held a series of seminars to open and sustain a dialogue with residents ([ 3 ][4]). The municipality of Date City, which has various levels of contaminated areas, has used feedback about the experiences shared in these seminars to modify their administrative measures and policies and assign staff to explain the personal dosimeter measurement results to individual residents. They also carried out multiple projects to provide mental and physical care for small groups of residents. These activities were implemented based on advice of experts who were by the side of the residents. By putting a liaison in place, medical professionals and experts have transformed a unilateral communication about the risk of radiation into an actively bilateral communication to address the various needs for residents after the accident.nnEvacuees have been gradually returning to their homes since the designation of evacuation areas was lifted in Fukushima. At this time, they feel anxious about radiation exposure and life in their new environment. Integrated health systems and community dialogues should continue to provide the returning residents with the support they need.nn1. [↵][5]1. S. Nagataki 2. et aln ., Radiat. Res. 180, 439 (2013).n [OpenUrl][6][CrossRef][7][PubMed][8]nn2. [↵][9]1. M. Miyazakin , “Yorozu health consultation project,” 4th International Expert Symposium in Fukushima (2015); .n nn3. [↵][10]International Commission on Radiological Protection, ICRP and Fukushima ICRP Dialogue Initiative ([www.icrp.org/page.asp?id=189][11]).nn [1]: #ref-1n [2]: /lookup/doi/10.1126/science.351.6277.1022n [3]: #ref-2n [4]: #ref-3n [5]: #xref-ref-1-1 View reference 1 in textn [6]: {openurl}?query=rft.jtitle%253DRadiat.%2BRes.%26rft.volume%253D180%26rft.spage%253D439%26rft_id%253Dinfo%253Adoi%252F10.1667%252FRR13351.1%26rft_id%253Dinfo%253Apmid%252F24131040%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actxn [7]: /lookup/external-ref?access_num=10.1667/RR13351.1&link_type=DOIn [8]: /lookup/external-ref?access_num=24131040&link_type=MED&atom=%2Fsci%2F352%2F6286%2F666.2.atomn [9]: #xref-ref-2-1 View reference 2 in textn [10]: #xref-ref-3-1 View reference 3 in textn [11]: http://www.icrp.org/page.asp?id=189

Comparison of Alzheimer’s disease with vascular dementia and non-dementia using specific voxel-based Z score maps

ObjectiveWe investigated the ability to discriminate between Alzheimer’s disease (AD) and vascular dementia (VaD), and between AD and non-dementia using the program “easy Z score imaging system” (eZIS) developed by Matsuda et al., for the diagnosis of very early AD.MethodsOf 201 patients, we investigated 12 patients with AD, 10 with VaD, and 9 with non-dementia, who underwent brain perfusion single-photon emission computed tomography by technetium-99m ethyl cysteinate dimer (99mTc-ECD) between February 2005 and September 2006. The sensitivity and specificity of the indicators of specific volume of interest (VOI) analysis, namely, severity, extent, and ratio were evaluated for the distinction of AD from VaD and non-dementia.ResultsThere was a significant difference in all the criteria for severity, extent, and ratio between AD and non-dementia cases and in the ratio between AD and VaD. Between AD and non-dementia, the sensitivity and specificity of severity were 100% and 45%, respectively, using the cutoff value of 1.19. When using the cutoff value of 14.2 for extent, the sensitivity and specificity were both 100%. Using the cutoff value of 2.22 for ratio, the sensitivity of 42% and specificity of 100% were demonstrated. When comparing AD with VaD, using the cutoff value of 2.22 for ratio, the sensitivity and specificity were 42% and 100%, respectively. Using the cutoff value of 1.5 for ratio, the sensitivity and specificity between AD and VaD were 92% and 80%, respectively, thereby showing the best results.ConclusionsThe specific VOI analysis program of AD using specific voxel-based Z score maps is not influenced by interobserver differences among radiologists and is useful to discriminate AD from VaD and non-dementia. However, the setting of the cutoff value at each institution and comparison with original and eZIS images are suggested to distinguish better AD from VaD.

Individual external dose monitoring of all citizens of Date City by passive dosimeter 5 to 51 months after the Fukushima NPP accident (series): II. Prediction of lifetime additional effective dose and evaluating the effect of decontamination on individual dose

In the first paper of this series, we showed that the ratio c of individual dose to ambient dose did not change with time in Date City, Fukushima Prefecture, after the Fukushima Daiichi Nuclear Power Plant accident. The purpose of the present paper, the second in a series, is to estimate the lifetime doses of the Date City residents, based on continuous glass badge monitoring data, extrapolated by means of the ambient-dose-rate reduction function obtained from the airborne monitoring data. As a result, we found that the external exposure contribution to the mean additional lifetime dose of residents living in Date City is not expected to exceed 18 mSv. In addition, effects of decontamination on the reduction of individual doses were not evident. This method of combining individual doses and the ambient doses, as developed in this study, has made it possible to predict with reasonable certainty the lifetime doses of residents who continue to live in this radiologically contaminated area.

Imaging findings at the donor site after iliac crest bone harvesting

ObjectivePostoperative imaging after iliac crest bone harvesting is commonly performed, but has not been extensively reported in the literature. The objective of this analysis was to investigate the donor site after iliac crest graft harvesting.Materials and MethodsBetween January and December 2008, 3,450 patients underwent CT, which included the pelvis. Eighty-four patients were found whose iliac crests were harvested. The patient population consisted of 47 male and 37 female subjects ranging from 10 to 80xa0years old (mean 52.6xa0years) at the time of iliac bone harvesting. With the inclusion of prior examinations, 188 CT examinations, 17 MR imaging studies, and 19 bone scintigrams were analyzed at various time points after surgery.ResultsComputed tomography images demonstrated fluid collections, hematoma, and air at the donor site up to 1xa0month after bone harvesting. The air then disappeared. Fluid collection decreased in size by 4xa0months. Scar-like changes at the harvest site and irregular thick cortical bone were observed after 4xa0months. Later, CT and MR imaging demonstrated small scar-like lesions and cortical irregularities.ConclusionThe appearance of harvest site abnormalities depends on the time elapsed after surgery.

Comparison of the UNSCEAR isodose maps for annual external exposure in Fukushima with those obtained based on the airborne monitoring surveys

In 2016, UNSCEAR published an attachment to its Fukushima 2015 White Paper, entitled Development of isodose maps representing annual external exposure in Japan as a function of time, in which the committee presented an annual additional 1 mSv effective dose ab extra isodose lines for 1, 3, 5, 10, 30, 50 years after the accident, based on the soil deposition data of radionuclides within 100 km of the Fukushima Dai-ichi Nuclear Power Plant. Meanwhile, the median of the ratio, c, between the external effective dose rates and the ambient dose equivalent rates 1 m above the ground obtained by airborne monitoring has been established to be [Formula: see text]. Here, we compare the UNSCEAR predictions with estimates based on the airborne monitoring. Although both the methods and the data used in the two approaches are different, the resultant contours show relatively good agreement. However, to improve the accuracy of long-term annual effective isodose lines, feedback from continuous measurements such as airborne monitoring is important.