TABLE III.
Ion chamber results for the spine and dental phantoms (averaged over 2 repeat irradiations). For each chamber location, the ratio of the measured dose with metal implants in place to the dose measured without metal is presented to highlight the true impact of the metal. Additionally, the % error between calculated (Philips 120 kVp uncorrected imaging) and measured doses are shown for both the no-metal case and the case with metal implants.
| % error(calculated vs measured) | ||||
|---|---|---|---|---|
| Phantom | Ion chamber | Measured ratio (with metal/no metal) | No metal | With metal |
| Spine phantom | 1 | 0.999 | 3.5 | 4.2 |
| 2 | 0.973 | 1.3 | 1.8 | |
| 3 | 1.006 | 1.8 | 1.6 | |
| 4 | 1.002 | −0.8 | −0.7 | |
| Dental phantom | 1 | 0.999 | 3.0 | −11.5 |
| 2 | 1.004 | 1.7 | −7.5 | |
| 3 | 0.977 | −0.9 | −10.2 | |
| 4 | 0.966 | 0.8 | −0.3 | |