Abstract
Purpose: To verify whether Icon automatic correction is robust in preserving plan quality. Materials/methods: An end-to-end phantom was used to verify Icon's correction accuracy qualitatively. For quantitative assessment, two plans, a composite- and a uniform-shot-only, were created for an elliptical- (E) and a sausage-shaped (S) lesion inside a PseudoPatient head phantom with a film insert. The phantom was irradiated in the planned and three other positions under each plan: 14° pitch (B); 14° rotation + 8° pitch (C); 95° rotation + 4-cm shift (D). Results: Icon accurately corrects the locations of the shots. For the uniform-shot plans: all gamma index passing rates were >97%, and the differences between the planned and the delivery doses (minimum, maximum, and mean) were all ≤0.1 Gy. For the composite-shot plans, however, the dose differences increased as the phantom was shifted through positions B-D, with a gamma index passing rate of 61% for lesion-E in position D, and 92%, 79%, and 45% for lesion-S in positions B, C, and D, respectively. Conclusions: Plans using only uniform shots are more robust to deviations in treatment position. The tolerance for such deviations may be lower for plans using composite shots.
Original language | English (US) |
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Pages (from-to) | 135-157 |
Number of pages | 23 |
Journal | Physica Medica |
Volume | 73 |
DOIs | |
State | Published - May 2020 |
Keywords
- Gamma Knife Icon
- Robust planning
- Shot correction
- Uniform and composite shots
ASJC Scopus subject areas
- Biophysics
- Radiology Nuclear Medicine and imaging
- General Physics and Astronomy