TABLE 6.
Measured (EBT‐XD film) and calculated (AAA v15.6) virtual‐cone dose widths determined for a single patient. Separate quality assurance (QA) plans were developed for the coronal and sagittal plane measurements. The sagittal plane calculation and measurement were performed for a stereotactic radiosurgery (SRS) phantom containing multiple heterogeneity inserts. These inserts were not present for the coronal plane QA, which accounts for the small differences in the calculated superior‐inferior (S‐I) widths between the two planes. The dose widths were determined from orthogonal profiles (see Figure 3) that intersect the center of the dose distribution. The measured values shown below were reduced by 2% to correct for the film image and smoothing resolution
| Coronal plane | ||||
|---|---|---|---|---|
| Dose profile direction | Isodose width | Measurement (mm) | Calculation (mm) | Difference (mm) |
|
Left‐Right (L‐R) |
50% | 5.21 ± 0.07 | 5.06 | 0.15 ± 0.07 |
| 25% | 8.66 ± 0.12 | 8.31 | 0.35 ± 0.12 | |
|
Superior‐Inferior (S‐I) |
50% | 5.12 ± 0.07 | 5.28 | −0.16 ± 0.07 |
| 25% | 8.53 ± 0.12 | 8.38 | 0.15 ± 0.12 | |
| Sagittal plane | ||||
|---|---|---|---|---|
| Dose profile direction | Isodose width | Measurement (mm) | Calculation (mm) | Difference (mm) |
|
Anterior‐Posterior (A‐P) |
50% | 4.93 ± 0.07 | 4.91 | 0.02 ± 0.07 |
| 25% | 8.32 ± 0.12 | 8.08 | 0.24 ± 0.12 | |
|
Superior‐Inferior (S‐I) |
50% | 5.13 ± 0.07 | 5.12 | 0.01 ± 0.07 |
| 25% | 8.45 ± 0.12 | 8.24 | 0.21 ± 0.12 | |