Health physics最新文献

Background: A nationwide survey of x-ray imaging practices was conducted during 2014-2015 of a representative sample of US dental offices to gather data regarding patient exam frequencies, indicators for radiation dosimetry and related imaging data, and the data were compared to similar studies conducted during 1993 and 1999.

Purpose: The survey results are compared with prior surveys to observe trends in the state of dental x-ray practice, particularly with regard to the use of digital imaging technologies, including cone-beam computed tomography. A total of 199 dental offices were visited in 25 participating states, and comprehensive radiological data were gathered regarding intraoral, panoramic, and cone-beam CT imaging practices. Data were also gathered regarding pediatric x-ray imaging practices. State radiation control data registries of dental offices were combined with gathered survey data to infer total US annual exam and per-capita exam volumes for all three imaging modalities. The clinical applications of imaging modalities in dentistry are not studied in this paper.

Results: The number of intraoral x-ray exams performed annually in the US increased from approximately 191 million exams during 1993 to 296 million exams in 2014-2015. The per-capita rate also increased from 74 to 93 exams per 100 persons during the same period. The annual number of panoramic exams more than doubled from 11 million in 1993 to 21 million in 2014-2015. An estimated 3.5 million CBCT exams were conducted in dental offices in the US during 2014-2015, including 1.1 million exams on children and adolescents. Radiation dose from intraoral imaging decreased notably between 1993 and the most recent study in 2014-2015, from 1.9 mGy to 0.9 mGy.

Conclusion: The total US exam volume and per-capita exam rates for intraoral imaging have increased from 1993 to 1999; however, patient radiation dose (as measured by skin-entrance air kerma, Ka,e) decreased substantially. A major contributor to that observed reduction in radiation dose is the now-prevalent use of digital imaging methods for intraoral radiography.

Radon ( 222 Rn) is a naturally occurring radioactive gas and a significant cause of lung cancer globally, second only to inhaled tobacco smoke. This review examines radon exposure in Japan, its public health risks, current regulations, and mitigation strategies in the context of international standards. Studies show that Japan's indoor radon concentrations average around 15 Bq m -3 , significantly lower than the global mean of approximately 40 Bq m -3 . Furthermore, only a small percentage, estimated at 0.1 to 1%, of Japanese homes exceed the World Health Organization's reference level of 100 Bq m -3 . As a result, radon is responsible for a smaller proportion of lung cancer cases in Japan, around 4%, compared to many Western countries. Nonetheless, radon remains an important public health concern, especially as modern homes become more airtight, potentially elevating indoor radon levels. The review also explores the geographic distribution of radon in Japan, highlighting regions (e.g., parts of western Japan with granitic bedrock) that exhibit higher natural radioactivity. It assesses the absence of a comprehensive national radon regulation in Japan, contrasting it with numerous countries that have established reference levels, building codes, and action plans. This review discusses effective radon mitigation techniques, including active soil depressurization and improved ventilation, applicable to Japan's building context. It argues for a proactive national radon policy to promote routine monitoring, public awareness, and remediation of high-radon homes. Finally, it proposes forming an association of radon scientists and technologists in Japan to enhance research, training, and policy advocacy.