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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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Related in: MedlinePlus

Estimated annual numbers of CT examinations and scannings in Japan. The estimated annual number of patients who underwent CT in Japan was approximately 29.9 million. In approximately 50% of these patients, more than two anatomical locations were scanned in one CT session, thus the number of CT examinations was about 45.3 million annually. In addition, approximately 37% of the patients underwent more than two scans of the same anatomical location (for instance, unenhanced and enhanced CT), making the number of scans about 62.5 million annually.
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Figure 2: Estimated annual numbers of CT examinations and scannings in Japan. The estimated annual number of patients who underwent CT in Japan was approximately 29.9 million. In approximately 50% of these patients, more than two anatomical locations were scanned in one CT session, thus the number of CT examinations was about 45.3 million annually. In addition, approximately 37% of the patients underwent more than two scans of the same anatomical location (for instance, unenhanced and enhanced CT), making the number of scans about 62.5 million annually.

Mentions: The estimated annual number of adult patients who underwent CT in Gunma prefecture during the month surveyed was 471,557 (Table 2). The estimated annual number of patients undergoing CT per 1000 population would be 235.4. In approximately 50% of the patients, more than two anatomical locations were examined in one CT session; the estimated annual number of examinations in Japan was 45.4 million (Figure 2; Table 3). In addition, approximately 37% of the patients underwent more than two scans of the same anatomical location (for instance, unenhanced and enhanced CT). CT examinations of the chest were the most frequent (27%), closely followed by examinations of the upper abdomen (23%), the neck (22%) and head (20%), with examinations of the lower abdomen (5%) and face (3%) being much less frequent. The number of CT examinations for men were larger than those for women.


Radiation exposure from CT examinations in Japan.

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

Estimated annual numbers of CT examinations and scannings in Japan. The estimated annual number of patients who underwent CT in Japan was approximately 29.9 million. In approximately 50% of these patients, more than two anatomical locations were scanned in one CT session, thus the number of CT examinations was about 45.3 million annually. In addition, approximately 37% of the patients underwent more than two scans of the same anatomical location (for instance, unenhanced and enhanced CT), making the number of scans about 62.5 million annually.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: Estimated annual numbers of CT examinations and scannings in Japan. The estimated annual number of patients who underwent CT in Japan was approximately 29.9 million. In approximately 50% of these patients, more than two anatomical locations were scanned in one CT session, thus the number of CT examinations was about 45.3 million annually. In addition, approximately 37% of the patients underwent more than two scans of the same anatomical location (for instance, unenhanced and enhanced CT), making the number of scans about 62.5 million annually.
Mentions: The estimated annual number of adult patients who underwent CT in Gunma prefecture during the month surveyed was 471,557 (Table 2). The estimated annual number of patients undergoing CT per 1000 population would be 235.4. In approximately 50% of the patients, more than two anatomical locations were examined in one CT session; the estimated annual number of examinations in Japan was 45.4 million (Figure 2; Table 3). In addition, approximately 37% of the patients underwent more than two scans of the same anatomical location (for instance, unenhanced and enhanced CT). CT examinations of the chest were the most frequent (27%), closely followed by examinations of the upper abdomen (23%), the neck (22%) and head (20%), with examinations of the lower abdomen (5%) and face (3%) being much less frequent. The number of CT examinations for men were larger than those for women.

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