Table 1.
A summary of correlation ratios for the sampling region (dose per escaped Cherenkov photon), % relative standard deviation values and sampling depths for x-ray beams, the two values in each box represent those values for entrance and then exit sides of the tissue.
| Factor Examined |
Range of correlation ratio (Dose (Gy) per escaped Cherenkov photon×10−7) |
Relative standard deviation (%) (std. dev./mean) |
Sampling depth (mm) | |||
|---|---|---|---|---|---|---|
| Entrance | Exit | Entrance | Exit | Entrance | Exit | |
| Skin color range light to dark | 3.5 ~ 8.6 | 1.6 ~ 4.1 | 42* | 45* | 5.7 ~ 6.2 | 2.1 ~ 2.7 |
| Nominal photon energy (MV) 4–15 MV | 4.3 ~ 2.5 | 1.9 ~ 1.1 | 21* | 22* | 5.4 ~ 6.0 | 2.1 ~ 2.0 |
| Curved surface 0–180° (10cm diam.) | 3.4 ~ 2.2 | 2.2 ~ 1.6 | 18* | 14* | 5.0 ~ 3.1 | 3.1 ~ 2.4 |
| Field size –0.5 to 20 cm square | 3.8 ~ 3.4 | 1.4 ~ 1.7 | 4.0 | 5.0* | 6.3 ~ 5.1 | 2.0 ~ 2.1 |
| Thickness 2.5 – 20 cm | 3.5 ~ 3.6 | 1.6 ~ 1.5 | 0.73 | 2.3 | 5.7 ~ 5.7 | 2.1 ~ 2.1 |
| Curvature 2.5 – 20cm diam. | 3.0 ~ 2.9 | 1.9 ~ 1.8 | 1.4 | 1.2 | 4.0 ~ 4.3 | 2.4 ~ 2.6 |
| SSD 80–120 cm | 3.5 ~ 3.6 | 1.5 ~ 1.6 | 0.21 | 1.1 | 5.7 ~ 5.7 | 2.1 ~ 2.1 |
Those values with greater than a 5% effect are noted (*)