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Radiation exposure from CT examinations in Japan.

Tsushima Y, Taketomi-Takahashi A, Takei H, Otake H, Endo K - BMC Med Imaging (2010)

Bottom Line: There was a large variation in effective dose among hospitals surveyed, particularly in lower abdominal CT (range, 2.6-19.0 mSv).It was estimated that in Japan, approximately 29.9 million patients undergo CT annually, and the estimated annual collective effective dose in Japan was 277.4 *103 Sv person.The annual effective dose per capita for Japan was estimated to be 2.20 mSv.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Diagnostic Radiology and Nuclear Medicine, Gunma University Hospital 3-39-22 Showa-machi, Maebashi, Gunma, Japan. tyoshito@showa.gunma-u.ac.jp

ABSTRACT

Background: Computed tomography (CT) is the largest source of medical radiation exposure to the general population, and is considered a potential source of increased cancer risk. The aim of this study was to assess the current situation of CT use in Japan, and to investigate variations in radiation exposure in CT studies among institutions and scanners.

Methods: Data-sheets were sent to all 126 hospitals and randomly selected 14 (15%) of 94 clinics in Gunma prefecture which had CT scanner(s). Data for patients undergoing CT during a single month (June 2008) were obtained, along with CT scan protocols for each institution surveyed. Age and sex specific patterns of CT examination, the variation in radiation exposure from CT examinations, and factors which were responsible for the variation in radiation exposure were determined.

Results: An estimated 235.4 patients per 1,000 population undergo CT examinations each year, and 50% of the patients were scanned in two or more anatomical locations in one CT session. There was a large variation in effective dose among hospitals surveyed, particularly in lower abdominal CT (range, 2.6-19.0 mSv). CT examinations of the chest and upper abdomen contributed to approximately 73.2% of the collective dose from all CT examinations. It was estimated that in Japan, approximately 29.9 million patients undergo CT annually, and the estimated annual collective effective dose in Japan was 277.4 *103 Sv person. The annual effective dose per capita for Japan was estimated to be 2.20 mSv.

Conclusions: There was a very large variation in radiation exposure from CT among institutions surveyed. CT examinations of the chest and upper abdomen were the predominant contributors to the collective dose.

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Age distribution of the population of Japan and Gunma prefecture. The distributions are very similar.
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Figure 1: Age distribution of the population of Japan and Gunma prefecture. The distributions are very similar.

Mentions: A questionnaire was mailed to the chief radiologic technologist in all 126 hospitals and randomly selected 14 (15%) of 94 clinics which had CT scanner(s) in Gunma prefecture (state). Gunma prefecture is located approximately 100 km north of Tokyo, and its population is two million. The age distribution in Gunma prefecture is very similar to that of Japan as a whole (Figure 1) [6], and we suspect that the medical environment in Gunma prefecture probably reflects that of the Japanese national average (Table 1) [7-11]. The chief technologist in each hospital was asked to make a list of all patients who underwent CT during a period of one month (June 2008). The data of each patient (CT session) consisted of the patient's age and sex, anatomical location of the CT scan and number of scans. When a patient returned for a second or more CT session on a different day, the sessions were counted as two different patients each undergoing a single CT session. The anatomical locations were divided into head, face, neck, chest, upper abdomen, lower abdomen (pelvis) and other.


Radiation exposure from CT examinations in Japan.

Tsushima Y, Taketomi-Takahashi A, Takei H, Otake H, Endo K - BMC Med Imaging (2010)

Age distribution of the population of Japan and Gunma prefecture. The distributions are very similar.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2984464&req=5

Figure 1: Age distribution of the population of Japan and Gunma prefecture. The distributions are very similar.
Mentions: A questionnaire was mailed to the chief radiologic technologist in all 126 hospitals and randomly selected 14 (15%) of 94 clinics which had CT scanner(s) in Gunma prefecture (state). Gunma prefecture is located approximately 100 km north of Tokyo, and its population is two million. The age distribution in Gunma prefecture is very similar to that of Japan as a whole (Figure 1) [6], and we suspect that the medical environment in Gunma prefecture probably reflects that of the Japanese national average (Table 1) [7-11]. The chief technologist in each hospital was asked to make a list of all patients who underwent CT during a period of one month (June 2008). The data of each patient (CT session) consisted of the patient's age and sex, anatomical location of the CT scan and number of scans. When a patient returned for a second or more CT session on a different day, the sessions were counted as two different patients each undergoing a single CT session. The anatomical locations were divided into head, face, neck, chest, upper abdomen, lower abdomen (pelvis) and other.

Bottom Line: There was a large variation in effective dose among hospitals surveyed, particularly in lower abdominal CT (range, 2.6-19.0 mSv).It was estimated that in Japan, approximately 29.9 million patients undergo CT annually, and the estimated annual collective effective dose in Japan was 277.4 *103 Sv person.The annual effective dose per capita for Japan was estimated to be 2.20 mSv.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Diagnostic Radiology and Nuclear Medicine, Gunma University Hospital 3-39-22 Showa-machi, Maebashi, Gunma, Japan. tyoshito@showa.gunma-u.ac.jp

ABSTRACT

Background: Computed tomography (CT) is the largest source of medical radiation exposure to the general population, and is considered a potential source of increased cancer risk. The aim of this study was to assess the current situation of CT use in Japan, and to investigate variations in radiation exposure in CT studies among institutions and scanners.

Methods: Data-sheets were sent to all 126 hospitals and randomly selected 14 (15%) of 94 clinics in Gunma prefecture which had CT scanner(s). Data for patients undergoing CT during a single month (June 2008) were obtained, along with CT scan protocols for each institution surveyed. Age and sex specific patterns of CT examination, the variation in radiation exposure from CT examinations, and factors which were responsible for the variation in radiation exposure were determined.

Results: An estimated 235.4 patients per 1,000 population undergo CT examinations each year, and 50% of the patients were scanned in two or more anatomical locations in one CT session. There was a large variation in effective dose among hospitals surveyed, particularly in lower abdominal CT (range, 2.6-19.0 mSv). CT examinations of the chest and upper abdomen contributed to approximately 73.2% of the collective dose from all CT examinations. It was estimated that in Japan, approximately 29.9 million patients undergo CT annually, and the estimated annual collective effective dose in Japan was 277.4 *103 Sv person. The annual effective dose per capita for Japan was estimated to be 2.20 mSv.

Conclusions: There was a very large variation in radiation exposure from CT among institutions surveyed. CT examinations of the chest and upper abdomen were the predominant contributors to the collective dose.

Show MeSH
Related in: MedlinePlus