Table 1.
Characteristics of each field for the 30.6-Gy, 6-MV CSI treatment. For easier readability, the characteristics of the fields of feathered junctions and field-in-field fields were averaged (Y-jaw settings) or summed (monitor units) in this table.
| AUBMC Fields |
||||
|---|---|---|---|---|
| Description | Right Cranial | Left Cranial | Upper Spinal | Lower Spinal |
| Monitor units | 1701 | 1665 | 3374 | 3656 |
| Gantry angle (°) | 90 | 270 | 0 | 0 |
| Collimator angle (°) | 5.0 | 355.0 | 0 | 0 |
| Dose to calculation point (Gy) | 15.3 | 15.3 | 30.6 | 30.6 |
| X1 jaw (cm) | −11.4 | −9.0 | −3.6 | −4.0 |
| X2 jaw (cm) | 9.0 | 11.4 | 3.1 | 5.0 |
| Y1 jaw (cm) | −9.3 | −9.3 | −12.4 | −17.7 |
| Y2 jaw (cm) | 15.1 | 15.1 | 9.6 | 15.0 |
| Water equivalent depth of calculation point (cm) | 7.64 | 7.86 | 3.74 | 5.66 |
| Effective square (cm) | 15.3 | 15.3 | 9.0 | 10.5 |
| Source-to-skin distance (cm) | 93.4 | 92.0 | 100.0 | 100.0 |
| MD Anderson Fields |
||||
|---|---|---|---|---|
| Description | Right Cranial | Left Cranial | Upper Spinal | Lower Spinal |
| Monitor units | 1700 | 1700 | 3009 | 3213 |
| Gantry angle (°) | 270 | 90 | 0 | 0 |
| Collimator angle (°) | 8.0 | 352.0 | 0 | 0 |
| Dose to calculation point (Gy) | 15.4 | 15.4 | 32.6* | 32.4* |
| X1 jaw (cm) | −12.0 | −12 | −4.2 | −5.3 |
| X2 jaw (cm) | 12.0 | 12 | 4.3 | 4.8 |
| Y1 jaw (cm) | −13.0 | −13.0 | −13.5 | −14.0 |
| Y2 jaw (cm) | 11.0 | 11.0 | 14.6 | 14.6 |
| Water equivalent depth of calculation point (cm) | 10.3 | 10.3 | 4.2 | 6.7 |
| Effective square (cm) | 15.0 | 15.0 | 13.0 | 14.9 |
| Source-to-skin distance (cm) | 92.1 | 92.1 | 100 | 100 |
*
The spinal fields were normalized to deliver a DRx of 30.6 Gy before the field-in-field fields were added to the plan. The addition of these fields resulted in a 6% increase in the absorbed dose at the calculation points of the spinal fields for the MD Anderson plan. This did not affect the model results because the model was reported in absorbed dose per prescribed dose.