Table 1.
CTV volume and magnitude of motion calculated from the center of mass of the structures both with verification imaging shift (workflow B) and without (workflow C)
| CTV volume (cm3) |
COM shift (mm) (average ± SD) |
||||||
|---|---|---|---|---|---|---|---|
| Structure | Workflow | CBCTinit | CBCTverif | Lateral | Vertical | Longitudinal | 3D motion |
| Prostate | Workflow B | 57.1 ± 26.1 | 58.2 ± 27.2 | 0.0 ± 0.7 | 0.3 ± 1.6 | –0.2 ± 1.8 | 2.2 ± 1.3 |
| Workflow C | 0.3 ± 1.3 | 1.2 ± 2.4 | –0.7 ± 2.5 | 3.3 ± 2.2 | |||
| Seminal vesicles | Workflow B | 14.9 ± 7.8 | 15.7 ± 8.8 | 0.0 ± 1.5 | 0.4 ± 1.9 | 0.1 ± 2.1 | 2.8 ± 1.5 |
| Workflow C | 0.3 ± 1.8 | 1.5 ± 2.6 | 0.0 ± 2.5 | 3.7 ± 2.0 | |||
Abbreviations: 3D = 3-dimensional; CBCT = cone beam computed tomography; COM = center of mass; CTV = clinical target volume.
Positive lateral, vertical, and longitudinal values indicate a shift to the patient's left, posterior, and superior, respectively during the fraction. Note that individual components are averaged as vectors, whereas 3D motion is calculated as a scalar quantity (average of the square root of the sum of squares of each component).