Background
Methods
• Collecting the data of individual patients undergoing CT and standard CT scanning protocols
Variables | Gunma prefecture | National average | Year of the data (references) |
---|---|---|---|
Population density (/km
2
)
| 318 | 340 | 2006 |
Annual income per capita (Japanese yen)
| 2,828,000 | 2,978,000 | 2004 (21) |
Number of hospitals (/100,000 population)
| 6.9 | 6.9 | 2007 (19) |
Number of beds (/100,000 population)
| 1263 | 1268 | 2007 (20) |
Number of physicians (/100,000 population)
| 208.6 | 217.5 | 2006 (17) |
Annual medical cost per capita (Japanese yen)
| 343,000 | 386,000 | 2005 (18) |
• Calculation of the organ doses for each patient
• Estimations of effective dose for one scan or examination and annual collective dose in Japan
Results
• Data collection (Table 2)
Number of CT scanners | Estimated annual number of patients | |||||
---|---|---|---|---|---|---|
Total | Data obtained (%) | |||||
Complete data | Scanning protocol & Number of patients * | Mean | Range | Estimated total number | ||
Hospitals
| 132 | 63 | 61 | 2,571 | 36 - 23,616 | 339,393 |
Clinics
| 94 ** | 6 | 0 | 1,406 | 288 - 2,664 | 132,164 |
Total
| 226 | 69 | 61 | 471,557 |
• Numbers of patients, CT examinations, and scanning
CT examination | Annual number of CT examination (*106) | Annual collective dose (*103 Sv person) | |
---|---|---|---|
Head
| Total | 9.1 | 23.6 |
Men | 4.6 | 12.1 | |
Women | 4.5 | 11.5 | |
Face
| Total | 1.4 | 2.8 |
Men | 0.7 | 1.5 | |
Women | 0.7 | 1.3 | |
Neck
| Total | 10.1 | 26.5 |
Men | 5.6 | 14.8 | |
Women | 4.5 | 11.7 | |
Chest
| Total | 12.5 | 120.0 |
Men | 7.0 | 67.8 | |
Women | 5.5 | 52.2 | |
Upper abdomen
| Total | 10.3 | 83.1 |
Men | 5.7 | 47.1 | |
Women | 4.6 | 36.0 | |
Lower abdomen
| Total | 2.1 | 21.3 |
Men | 1.1 | 12.0 | |
Women | 1.0 | 9.3 | |
Total
| Total | 45.4 | 277.4 |
Men | 24.7 | 155.3 | |
Women | 20.8 | 122.1 |
Age range (yo) | |||||||||
---|---|---|---|---|---|---|---|---|---|
CT examination | 0-19 | 20-29 | 30-39 | 40-49 | 50-59 | 60-69 | 70-79 | 80- | Total |
Head
| 0.43 | 0.17 | 0.24 | 0.36 | 0.53 | 0.89 | 1.11 | 0.89 | 4.62 |
Face
| 0.12 | 0.06 | 0.06 | 0.06 | 0.10 | 0.14 | 0.08 | 0.07 | 0.69 |
Neck
| 0.17 | 0.10 | 0.28 | 0.36 | 0.86 | 1.66 | 1.53 | 0.64 | 5.60 |
Chest
| 0.09 | 0.10 | 0.25 | 0.43 | 0.91 | 1.86 | 2.10 | 1.26 | 7.00 |
Upper abdomen
| 0.10 | 0.09 | 0.21 | 0.36 | 0.74 | 1.58 | 1.67 | 0.94 | 5.69 |
Lower abdomen
| 0.02 | 0.02 | 0.04 | 0.07 | 0.13 | 0.31 | 0.32 | 0.18 | 1.09 |
Total
| 0.93 | 0.54 | 1.08 | 1.64 | 3.27 | 6.44 | 6.81 | 3.98 | 24.69 |
Age range (yo) | |||||||||
---|---|---|---|---|---|---|---|---|---|
CT examination | 0-19 | 20-29 | 30-39 | 40-49 | 50-59 | 60-69 | 70-79 | 80- | Total |
Head
| 0.10 | 0.17 | 0.23 | 0.29 | 0.50 | 0.73 | 1.14 | 1.34 | 4.50 |
Face
| 0.11 | 0.04 | 0.04 | 0.05 | 0.09 | 0.13 | 0.16 | 0.08 | 0.70 |
Neck
| 0.00 | 0.08 | 0.27 | 0.59 | 0.97 | 1.14 | 0.96 | 0.50 | 4.51 |
Chest
| 0.09 | 0.06 | 0.22 | 0.42 | 0.90 | 1.21 | 1.30 | 1.30 | 5.50 |
Upper abdomen
| 0.00 | 0.09 | 0.22 | 0.39 | 0.76 | 1.03 | 1.16 | 0.94 | 4.59 |
Lower abdomen
| 0.00 | 0.03 | 0.05 | 0.09 | 0.16 | 0.21 | 0.24 | 0.22 | 1.00 |
Total
| 0.30 | 0.47 | 1.03 | 1.83 | 3.38 | 4.45 | 4.96 | 4.38 | 20.80 |
• The estimated effective dose, and their distribution
CT examination | Effective dose for one scanning/one examination (mSv) | |||||
---|---|---|---|---|---|---|
Year Study | 2008 Current (Japan) | 2000 Japan (13) | 2002 Germany (15) | 2003 UK (16) | 2003-2004 Netherlands (14) | |
Head
| Scan | 2.5 | - | 2.2 | 0.8* | 1.9 |
Examination | 2.6 | 2.4 | 2.8 | 1.5 | - | |
Face
| Scan | 1.5 | - | 0.8 | - | - |
Examination | 2.0 | - | 0.8 | - | - | |
Neck
| Scan | 2.3 | - | - | - | - |
Examination | 2.6 | - | - | - | - | |
Chest
| Scan | 5.4 | - | 5.5 | 3.4* | 3.8 |
Examination | 9.6 | 9.1 | 5.7 | 5.8 | - | |
Upper abdomen
| Scan | 5.7 | - | 5.5 | 3.8* | 7.2 |
Examination | 8.1 | 12.9 | 11.5 | 5.3 | 10.2** | |
Lower abdomen
| Scan | 8.3 | - | 6.3 | - | - |
Examination | 10.3 | 10.5 | 7.2 | - | - |