Phantom C: Average CT Attenuation (HU) and PET Activity (kBq/mL) and SD in 4 ROIs: ROI_b and ROI_bt in Phantom Background Inside and Outside CT FOV, Respectively, and ROI_l1 and ROI_l2 in Hot Spheres Inside and on Edge of CT FOV
| Image | Phantom position | ROI_b (HU) | t test (P value) | ROI_bt (HU) | t test (P value) | ROI_l1 (HU) | ROI_l2 (HU) |
|---|---|---|---|---|---|---|---|
| CT | Center | −1 ± 16 | NA | 0 ± 15 | 0.05 | 3 ± 10 | 1 ± 11 |
| offset_trunc | 9 ± 22 | <0.001 | — | NA | 100 ± 200 | −500 ± 600 | |
| offset_ext | −15 ± 10 | <0.001 | −100 ± 20 | <0.001 | 70 ± 200 | −10 ± 150 | |
| (kBq/mL) | (kBq/mL) | (kBq/mL) | (kBq/mL) | ||||
| PET | Center | 5.8 ± 0.1 | NA | 6.0 ± 0.3 | <0.001 | 37 ± 10 | 43 ± 15 |
| offset_trunc | 5.8 ± 0.2 | 3 (NS) | 0.6 ± 0.2 | <0.001 | 20 ± 5 | 8 ± 7 | |
| offset_ext | 5.7 ± 0.2 | 0.02 | 6 ± 1 | 3 (NS) | 31 ± 10 | 36 ± 12 |
For location of ROIs, see Figure 1C. P values were calculated for CT and PET values independently. We used 2-tailed, paired Student t test with Bonferroni correction. Significances were calculated for background only in reference to nontruncated ROI_b.
NA = not applicable; NS = not statistically significant.