ROI Counts Over 57Co Source in Air and Over PT at 3 Energy Windows
| Study no. | TS windows | PT windows | TS/PT ratio outlining performance | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Lower | Middle | Upper | Lower | Middle | Upper | Lower | Middle | Upper | ||||||||||
| Group 1 | ||||||||||||||||||
| 1 | 1,776 | 226 | 168 | 131 | 27 | 47 | 13.6 | 8.4 | 3.6 | |||||||||
| 2 | 2,068 | 157 | 186 | 169 | 12 | 32 | 12.2 | 13.1 | 5.8 | |||||||||
| 3 | 2,192 | 126 | 208 | 179 | 15 | 57 | 12.3 | 8.4 | 3.7 | |||||||||
| 4 | 1,643 | 178 | 142 | 136 | 21 | 48 | 12.1 | 8.5 | 3.0 | |||||||||
| 5 | 1,615 | 115 | 180 | 137 | 9 | 37 | 11.8 | 12.8 | 4.9 | |||||||||
| 6 | 2,107 | 75 | 157 | 113 | 13 | 37 | 18.7 | 5.8 | 4.2 | |||||||||
| 7 | 1,945 | 104 | 170 | 133 | 29 | 87 | 14.6 | 3.6 | 2.0 | |||||||||
| 8 | 1,911 | 170 | 143 | 70 | 7 | 18 | 27.3 | 24.3 | 8.0 | |||||||||
| 9 | 2,470 | 280 | 221 | 181 | 50 | 155 | 13.7 | 5.6 | 1.4 | |||||||||
| 10 | 1,818 | 84 | 167 | 101 | 4 | 30 | 18 | 21 | 5.6 | |||||||||
| Average | 1,955 | 151.5 | 174.2 | 135 | 18.7 | 54.8 | 15.4 | 11.1 | 4.2 | |||||||||
| ± SD | 263.1 | 64.8 | 25.7 | 35.1 | 13.7 | 38.9 | 4.8 | 6.8 | 1.9 | |||||||||
| Group 2 | ||||||||||||||||||
| 1 | 652 | 25 | 53 | 130 | 17 | 104 | 5.0 | 1.5 | 0.5 | |||||||||
| 2 | 650 | 37 | 59 | 67 | 7 | 16 | 9.7 | 5.3 | 3.7 | |||||||||
| 3 | 696 | 26 | 52 | 108 | 12 | 56 | 6.4 | 2.2 | 0.9 | |||||||||
| 4 | 674 | 46 | 56 | 92 | 16 | 47 | 7.3 | 2.9 | 1.2 | |||||||||
| 5 | 612 | 69 | 70 | 53 | 10 | 22 | 11.6 | 6.9 | 3.2 | |||||||||
| 6 | 589 | 25 | 58 | 55 | 7 | 22 | 10.7 | 3.6 | 2.6 | |||||||||
| 7 | 636 | 46 | 52 | 69 | 7 | 23 | 9.2 | 6.6 | 2.3 | |||||||||
| 8 | 693 | 29 | 54 | 167 | 24 | 50 | 4.2 | 1.2 | 1.1 | |||||||||
| 9 | 661 | 57 | 51 | 136 | 38 | 102 | 4.9 | 1.5 | 0.5 | |||||||||
| 10 | 601 | 31 | 55 | 35 | 6 | 22 | 17.7 | 5.2 | 2.5 | |||||||||
| Average | 646.4 | 39.1 | 56 | 91.2 | 14.4 | 46.4 | 8.6 | 3.7 | 1.8 | |||||||||
| ± SD | 37.0 | 15.1 | 5.6 | 42.9 | 10.1 | 33.0 | 4.0 | 2.2 | 1.1 | |||||||||
Counts are for same-sized ROI (15 × 40 pixels) over patient (PT) and over nonattenuated area of transmission source (TS) for individual group 1 and group 2 studies (n = 10 each). Counts in lower, middle, and upper energy windows in ROI over patient and transmission source are listed for energy windows described in text (group 1: 115–129, 130–134, and 135–150 keV; group 2: 112–132, 130–134, and 135–150 keV). Outlining performance, defined as ratio of counts in ROI over transmission source relative to ROI over patient (TS/PT) for a particular energy window are noted. The higher the ratio the bigger the difference between patient and outlining source and the better the “contrast.” Average values of all patients for these indices in each group are presented.