Table 5.
Highest sample size required for three- or one-region approach for helical chest protocol performed on 320-row scanner, as a function of anticipated effective dose, precision, and desired confidence level. Sample sizes displayed are for confidence level of 95%, with sample sizes for 90% confidence level in parentheses.
| Precision | Anticipated effective dose (mSv) |
||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| (q [%]) | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 |
| 2 | 8402(6941) | 2101(1736) | 934(772) | 526(434) | 337(278) | 234(193) | 172(142) | 132(109) | 104(86) | 85(70) | 70(58) | 59(49) | 50(42) | 43(36) | 38(31) |
| 5 | 476(262) | 119(66) | 53(30) | 30(17) | 20(11) | 14(8) | 10(6) | 8(5) | 6(4) | 5(3) | 4(3) | 4(2) | 3(2) | 3(2) | 3(2) |
| 10 | 73(49) | 19(13) | 9(6) | 5(4) | 3(2) | 3(2) | 2(1) | 2(1) | 1(1) | 1(1) | 1(1) | 1(1) | 1(1) | 1(1) | 1(1) |
| 15 | 30(21) | 8(6) | 4(3) | 2(2) | 2(1) | 1(1) | 1(1) | 1(1) | 1(1) | 1(1) | 1(1) | 1(1) | 1(1) | 1(1) | 1(1) |
| 20 | 17(12) | 5(3) | 2(2) | 2(1) | 1(1) | 1(1) | 1(1) | 1(1) | 1(1) | 1(1) | 1(1) | 1(1) | 1(1) | 1(1) | 1(1) |
| 50 | 3(2) | 1(1) | 1(1) | 1(1) | 1(1) | 1(1) | 1(1) | 1(1) | 1(1) | 1(1) | 1(1) | 1(1) | 1(1) | 1(1) | 1(1) |