The present state of radiation exposure from pediatric CT examinations in Japan—what do we have to do?

Ideguchi, Reiko; Yoshida, Kōji; Ohtsuru, Akira; Takamura, Noboru; Tsuchida, Tatsuro; Kimura, Hirohiko; Uetani, Masataka; Kudo, Takashi

doi:10.1093/jrr/rrx095

Cited by 20 publications

(20 citation statements)

References 29 publications

(36 reference statements)

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“…Increasing or decreasing the median brain dose by 15% would change the excess cases by ±3 cases in total and the fractional ratio by ±0.7%. Increasing the 75th percentile of each dose distribution by 15% to account for a wider variation in scanning practices and associated exposures 41 had a similar impact on the results. Whereas more pediatric CT examinations were assumed to be performed on males than on females, as observed in Japan and elsewhere, 28,30,35 changing the sex ratio (male 62.3%, female 37.7%) to the equally balanced or the opposite ratio resulted in a substantial reduction in the total excess cases by 26% to 37% and the ratio by 24% to 33%.…”

Section: Resultsmentioning

confidence: 77%

Evaluation of the lifetime brain/central nervous system cancer risk associated with childhood head CT scanning in Japan

Kadowaki

Hamada

Kai

et al. 2020

Intl Journal of Cancer

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The use of computed tomography (CT) scanning has increased worldwide over the decades, and Japan is one of the leading countries in annual frequency of diagnostic CT. Although benefits of CT scan are undisputable, concerns have been raised about potential health effects of ionizing radiation exposure from CT, particularly among children who are likely more susceptible to radiation than adults. Our study aims to evaluate the cumulated lifetime risk of the brain/central nervous system (CNS) cancer due to head CT examinations performed on Japanese children at age 0 to 10 years in 2012, 2015 and 2018. The frequency and dose distribution of head CT examinations were estimated based on information from recent national statistics and nationwide surveys. The lifetime risk attributable to exposure was calculated by applying risk models based on the study of Japanese atomic‐bomb survivors. In contrast to the overall increasing trend, the frequency of childhood CT, especially at age < 5, was decreasing, reflecting a growing awareness for efforts to reduce childhood CT exposure over the past decade. In 2018, 138 532 head CT examinations were performed at age 0 to 10, which would consequently induce a lifetime excess of 22 cases (1 per 6300 scans) of brain/CNS cancers, accounting for 5% of the total cases. More excess cases were estimated among men than among women, and excess cases could emerge at relatively young ages. These results would have useful implications as scientific basis for future large‐scale epidemiological studies and also as quantitative evidence to justify the benefits of CT vs risks in Japan.

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Section: Resultsmentioning

confidence: 77%

Evaluation of the lifetime brain/central nervous system cancer risk associated with childhood head CT scanning in Japan

Kadowaki

Hamada

Kai

et al. 2020

Intl Journal of Cancer

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“…Therefore, we believe that some of the excess doses revealed in this study have been reviewed. Investigating the impact of the publication of DRLs with a longitudinal study is necessary [22].…”

Section: Jrprmentioning

confidence: 99%

Estimating Organ Doses from Pediatric Cerebral Computed Tomography Using the WAZA-ARI Web-Based Calculator

2021

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Background: The use of computed tomography (CT) device has increased in the past few decades in Japan. Dose optimization is strongly required in pediatric CT examinations, since there is concern that an unreasonably excessive medical radiation exposure might increase the risk of brain cancer and leukemia. To accelerate the process of dose optimization, continual assessment of the dose levels in actual hospitals and medical facilities is necessary. This study presents organ dose estimation using pediatric cerebral CT scans in the Kyushu region, Japan in 2012 and the web-based calculator, WAZA-ARI (https://waza-ari.nirs.qst.go.jp). Materials and Methods:We collected actual patient information and CT scan parameters from hospitals and medical facilities with more than 200 beds that perform pediatric CT in the Kyushu region, Japan through a questionnaire survey. To estimate the actual organ dose (brain dose, bone marrow dose, thyroid dose, lens dose), we divided the pediatric population into five age groups (0, 1, 5, 10, 15) based on body size, and inputted CT scan parameters into WA-ZA-ARI.Results and Discussion: Organ doses for each age group were obtained using WAZA-ARI. The brain dose, thyroid dose, and lens dose were the highest in the Age 0 group among the age groups, and the bone marrow and thyroid doses tended to decrease with increasing age groups. All organ doses showed differences among facilities, and this tendency was remarkable in the young group, especially in the Age 0 group. This study confirmed a difference of more than 10fold in organ doses depending on the facility and CT scan parameters, even when the same CT device was used in the same age group. Conclusion:This study indicated that organ doses varied widely by age group, and also suggested that CT scan parameters are not optimized for children in some hospitals and medical facilities.

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“…Because children are more radiosensitive than adults, it is also important to measure the radiation dose and estimate the cancer risk [ 24 , 25 , 26 , 27 , 28 ].…”

Section: Introductionmentioning

confidence: 99%

Reducing the Breast Cancer Risk and Radiation Dose of Radiography for Scoliosis in Children: A Phantom Study

Nemoto

Chida

2020

Diagnostics

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Full-spinal radiographs (FRs) are often the first choice of imaging modality in the investigation of scoliosis. However, FRs are strongly related to breast cancer occurrence due to multiple large-field radiographic examinations taken during childhood and adolescence, which may increase the risk for breast cancer in adulthood among women with scoliosis. The purpose of this study was to consider various technical parameters to reduce the patient radiation dose of FRs for scoliosis. To evaluate breast surface doses (BSDs) in FRs, radio photoluminescence dosimeters were placed in contact with a child phantom. Using the PC-based Monte Carlo (PMC) program for calculating patient doses in medical X-ray examinations, the breast organ dose (BOD) and the effective dose were calculated by performing Monte Carlo simulations using mathematical phantom models. The BSDs in the posteroanterior (PA) view were 0.15–0.34-fold those in the anteroposterior (AP) view. The effective dose in the PA view was 0.4–0.61-fold that in the AP view. BSD measurements were almost equivalent to the BODs obtained using PMC at all exposure settings. During FRs, the PA view without an anti-scatter grid significantly reduced the breast dose compared to the AP view with an anti-scatter grid.

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The present state of radiation exposure from pediatric CT examinations in Japan—what do we have to do?

Cited by 20 publications

References 29 publications

Evaluation of the lifetime brain/central nervous system cancer risk associated with childhood head CT scanning in Japan

Evaluation of the lifetime brain/central nervous system cancer risk associated with childhood head CT scanning in Japan

Estimating Organ Doses from Pediatric Cerebral Computed Tomography Using the WAZA-ARI Web-Based Calculator

Reducing the Breast Cancer Risk and Radiation Dose of Radiography for Scoliosis in Children: A Phantom Study

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