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The details of different shell groups.
| Distance from PTV margin to shell (mm) | ||||||||
|---|---|---|---|---|---|---|---|---|
| 1st shell | 2nd shell | 3rd shell | 4th shell | 5th shell | 6th shell | 7th shell | 8th shell | |
| Two‐shell plan | 8 | 15 | – | – | – | – | – | – |
| Three‐shell plan | 5 | 8 | 15 | – | – | – | – | – |
| Four‐shell plan | 3 | 5 | 8 | 15 | – | – | – | – |
| Five‐shell plan | 3 | 5 | 8 | 15 | 25 | – | – | – |
| Six‐shell plan | 3 | 5 | 8 | 11 | 15 | 25 | – | – |
| Seven‐shell plan | 3 | 5 | 8 | 11 | 15 | 20 | 25 | – |
| Eight‐shell plan | 3 | 5 | 8 | 11 | 15 | 20 | 25 | 30 |
Abbreviations: PTV, planning target volume.
