Table 1.
Routine kV‐CBCT QA test items and tolerance used at our institution.
| Test Items | Daily | Monthly | Tolerance |
|---|---|---|---|
| Safety: collision interlocks | X | X | Functional |
| Rotation center and machine isocenter coincidence | X | X | 1.5 mm |
| CBCT image registration accuracy | X | 1 mm | |
| Couch movement accuracy after registration | X | 1 mm | |
| kV image and machine isocenter coincidence | X | 1 mm | |
| 2D kV image quality: low contrast resolution | X | 12 disks | |
| 2D kV image quality: high contrast resolution | X | 10 line‐pair | |
| CBCT image quality: uniformity and noise | X | 2%/2% | |
| CBCT image quality: low contrast resolution | X | 2% | |
| CBCT image quality: high spatial resolution | X | 4 line‐pair a | |
| CBCT image quality: geometrical accuracy | X | 1.04 mm |
a
The baseline value at the time of installation was 7 line‐pair (lp)/cm, but later the tolerance level was set to a realistically achievable value of 4 lp/cm.