Simulated FWHM (cm) for Parallel Beam and Fan Beam Collimators with Cubic Hole While Point Sources Are Located in Air and Water Phantoms
| Source–collimator surface distance (cm) | ||||
| z = 10 | z = 15 | |||
| Collimator | Air | Phantom (2 cm) | Air | Phantom (7 cm) |
| System parallel beam | 0.80 | 0.87 | 0.95 | 1.22 |
| Geometric parallel beam | 0.59 | 0.86 | ||
| System fan beam | 0.79 | 0.81 | 0.91 | 1.16 |
| Geometric fan beam | 0.58 | 0.82 | ||