Table 1. The measurement results (mean ± SD) under RT-setting and DR-setting.
| Test | Series | Slice location | Measurement index | RT (mean ± SD) | DR (mean ± SD) | Mann-Whitney (P value) |
|---|---|---|---|---|---|---|
| Geometric accuracy (mm) | T1 | Localizer | Phantom length | 147.8±0.2 | 147.9±0.2 | 0.22 |
| Slice 1 | Diameter (AP direction) | 190.7±0.3 | 190.7±0.2 | |||
| Slice 1 | Diameter (LR direction) | 191.4±0.2 | 191.0±0.2 | |||
| Slice 5 | Diameter (AP direction) | 190.7±0.5 | 190.6±0.3 | |||
| Slice 5 | Diameter (LR direction) | 191.1±0.2 | 190.5±0.3 | |||
| Slice 5 | Diameter (phantom’s UL to LR) | 190.8±0.3 | 190.6±0.2 | |||
| Slice 5 | Diameter (phantom’s UR to LL) | 191.0±0.2 | 190.5±0.2 | |||
| – | Mean diameter | 191.0±0.4 | 190.7±0.3 | <0.05 | ||
| Slice thickness accuracy (mm) | T1 | Slice 1 | Slice thickness | 5.2±0.1 | 5.1±0.1 | 0.34 |
| T2 | Slice 1 | Slice thickness | 5.0±0.1 | 5.0±0.1 | ||
| Slice position accuracy (mm) | T1 | Slice 1 | Bar difference | 1.4±0.7 | 0.7±1.0 | 0.41 |
| Slice 11 | Bar difference | –2.2±0.4 | –1.1±0.5 | |||
| T2 | Slice 1 | Bar difference | 1.5±0.2 | 0.8±0.9 | ||
| Slice 11 | Bar difference | –2.2±0.2 | –1.1±0.5 | |||
| Image intensity uniformity (%) | T1 | Slice 7 | PIU | 93.4±0.1 | 92.7±0.2 | <0.05 |
| T2 | Slice 7 | PIU | 93.3±0.2 | 93.1±0.3 | <0.05 | |
| Percent-signal ghosting | T1 | Slice 7 | Ghosting ratio | 0.0005±0.0003 | 0.0006±0.0003 | 0.39 |
| Low-contrast object detectability | T1 | Slices 8–11 | Total number of spoke | 31.0±1.3 | 36.9±0.8 | <0.05 |
| T2 | Slices 8–11 | Total number of spoke | 23.8±1.7 | 32.1±1.6 | <0.05 |
DR, diagnostic radiological; RT, radiotherapy; PIU, percent integral uniformity; LR, lower-right; UL, upper-left.