Dependence of radiation dose on the behavioral patterns among school children: a retrospective analysis 18 to 20 months following the 2011 Fukushima nuclear incident in Japan

Abstract

After radioactive incidents, the exposure risk in daily activities among children is a major public concern. However, there are limited methods available for evaluation of this risk, which is essential to future health risk management. To this end, this study assessed the relationship between behavioral patterns of school children and radiation exposure for a period of 18–20 months following the 2011 Fukushima nuclear incident. The assessed population comprised 520 school children from Minamisoma city, located 20 km north of the nuclear plant. Data for the doses were obtained using individual dosimeters and from results of a behavior survey administered by the City Office. The mean value of the doses in the study period was 0.34 mSv, with a standard deviation of 0.14 mSv, indicating an annual dose of ∼1.36 mSv, which includes doses from natural sources. Our results showed that behavior with respect to outdoor activities had no statistically significant relationship to the dose. A 0.1 μSv/h increase in the air dose rate at home was associated with a 10% increase in the dose; however, a 0.01 μSv/h increase in the air dose rate on the school grounds was associated with a 2% increase in the dose. This study indicates that the air contamination levels at the places where children spend most of their day are the significant predictors of the dose, as opposed to the levels at those outdoor locations in which short periods of time spent.

Breast cancer patient delay in Fukushima, Japan following the 2011 triple disaster: a long-term retrospective study

“…The methods of these measurements have been documented in detail in a previous study [40]. All monitored results are publicly available [41].…”

Comparison of photon volumetric modulated arc therapy, intensity-modulated proton therapy, and intensity-modulated carbon ion therapy for delivery of hypo-fractionated thoracic radiotherapy

“…Improving dose conformity for IMPT is important, because it may decrease the risk of radiation pneumonitis [ 31 ]. Although IMPT and CIRT, compared with 3D–CRT, have been shown to improve target volume coverage when multiple fields are used, IMRT has been shown to have better dose conformity and homogeneity than passively scattered PT [ 17 – 22 ]. Our study comparing IMPT and VMAT demonstrated similar findings.…”

“…PT has traditionally been shown to decrease the low dose volumes in the lungs [ 15 – 22 ]. IMPT, and especially IMPT arcs, compared with passively scattered PT, may further decrease the normal lung dose [ 16 , 17 , 19 , 20 ].…”

“…This improvement is due to PT’s physical properties, which allow for better normal tissue protection, while heavy ions’ increased radiobiological effectiveness (RBE) increases the tumorcidal effect of radiotherapy over photons [ 13 , 14 ]. PT’s dosimetric advantages have been shown in multiple studies [ 15 – 22 ]. Given these advantages, PT is increasingly being considered for the delivery of hypo-fractionated thoracic radiotherapy [ 23 , 24 ].…”

Using two detectors concurrently to monitor ambient dose equivalent rates in vehicle surveys of radiocesium contaminated land

“…The heterogeneous nature of ambient dose equivalent rates around roads raises the question of how to apply VBM results above roads for calculating annual effective doses (mSv/y) to the public. For Fukushima residents, annual effective doses are typically accrued inside homes, schools and offices (Naito et al, 2015;Nomura et al, 2016;Naito et al, 2016). For outdoor workers, such as farmers and workers in the decontamination, forestry and construction sectors, doses received outdoors away from roads are important.…”