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Dose Received by One-Year-Old Children During CT Scanning in Japan

S Suzuki¹*, S Shirakawa², Y Takei³, Y Matsunaga⁴, A Kawaguchi⁵, K Akahane⁶, Y Shimada⁷, (1) Fujita Health University, Toyoake, Aichi, (2) Fujita Health University, Toyoake-shi, Aichi-ken, (3) Hamamatsu University School of Medicine, University Hospital, Hamamatsu, Shizuoka, (4) Nagoya kyoritsu hospital, Nagoya, Aichi, (5) Fujita Health University, Toyoake-shi, Aichi-ken, (6) National Institute Radiological Sciences, Chiba-shi, Chiba-ken, (7) National Institute Radiological Sciences, Chiba-shi, Chiba-ken

SU-E-I-45 Sunday 3:00PM - 6:00PM Room: Exhibit Hall

Purpose: CT scanning involves a higher radiation dose compared with X-ray scanning, and children are believed to be more sensitive to radiation compared with adults. However, the reality of pediatric CT scanning in Japan is unclear. We therefore performed dose evaluation by using a pediatric phantom representing a one-year-old child in order to assess the actual dose received.

Methods:Dose measurement was performed under the protocols used in each institution. Solid-state detectors were used to measure doses. These solid-state detectors were placed at 150 points on the surface of and inside the phantom. The data obtained were used to calculate the average absorbed dose for each organ, which were multiplied by tissue weighting factors to derive the effective doses. This study covered cranial and abdominal plain CT scans. When positioning scanning was performed, this was included in dose measurements, which were evaluated for the entire scan series. Measurements were performed at 13 institutions using devices made by five manufacturers.

Results:The minimum dose received directly by the head during cranial CT scanning was 8 mGy, the maximum dose was 40 mGy, and the mean dose was 22 mGy. The minimum effective dose was 0.4 mSv, the maximum effective dose was 2 mSv, and the mean effective dose was 1 mSv. The minimum dose received directly by the stomach during abdominal CT scanning was 3 mGy, the maximum dose was 22 mGy, and the mean dose was 8 mGy. The minimum effective dose was 0.4 mSv, the maximum effective dose was 2 mSv, and the mean effective dose was 1 mSv.

Conclusion:The mean doses received from direct radiation during cranial and abdominal CTs were 22 mGy for the former and 8 mGy for the latter, an approximately threefold difference. There was almost no difference in effective dose, which was 1 mSv in both cases.

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