Table 1.
Definition of different terms used in the paper
| Word | Definition |
|---|---|
| Detected‐flux‐dynamic‐range | Ratio of maximum to minimum detected counts at the detector |
| Entrance‐energy‐fluence | Surrogate for dose, equal to the sum of incident energy within the object boundary, where I 0,(β,γ)(E) is the number of photons incident on object of energy E in ray of fan angle β and view γ, and S is a set of sinogram points corresponding to rays that pass inside the object boundary. |
| Conventional filter | A pre‐patient attenuator that is a fixed piece of hardware and has more thickness along its periphery |
| Dynamic bowtie filter | A pre‐patient attenuator that can adjust fluence transmission as a function of both fan and view angle |
| Perfect‐attenuator | A theoretical filter able to modulate each ray individually |
| Flat‐variance attenuator | A specific variant of a perfect‐attenuator that seeks to achieve perfectly flat variance in the projection domain (one way to achieve flat variance across images) |
| Maximum‐count‐rate | Maximum detected count rate (in million counts per second per square millimeter, Mcps/mm2) across all projection data within the object boundary (excluding 4.9 mm at skin line) |
| Noise‐map | An image of variance, calculated analytically by unfiltered‐backprojecting variance in projection space following Ref. 33. It represents the ensemble variance at each point in space (e.g., over many repeats). |
| Peak‐variance | The maximum value in the noise‐map within the object boundary (excluding 4.9 mm at skin line) |