Table 1.
Treatment planning objectives for 3-fraction APBI
| Structure | Dose objectives |
|---|---|
| Target evaluation | Interfraction interval should be ≥40 h |
| Whole breast (ipsilateral) | V12.3Gy <50% |
| PTV_EVAL | V23.4Gy ≥95% |
| PTV | D2cm3 <107% (26.3 Gy), Dmax115% (28.3 Gy) <0.5 cm3 |
| CTV | V24.6Gy ≥95% |
| PTV and CTV conformality index | 0.95-1.2 |
| OAR evaluation | |
| Contralateral breast | Point dose <0.9 Gy |
| Ipsilateral lung | V7.7Gy <10%, V2.7Gy <20% |
| Contralateral lung | V1.4Gy <15% |
| Heart (right-sided lesions) | Mean dose <0.9 Gy, V4.0Gy ≤0% |
| Heart (left sided lesion, excluding lower inner quadrant) | V2.6Gy<5%, Mean dose<1.8 Gy |
| Heart (left sided lesion, lower inner quadrant) | V3.9Gy <5%, Mean dose <1.8 Gy |
| Ipsilateral brachial plexus | V24Gy <3.0 cm3, Point Dmax <25.6 Gy |
| Chest wall | V24Gy <30 cm3, Point Dmax <26 Gy |
| Skin | D0.5cm3 ≤100% (24.6 Gy) |
Abbreviations: APBI = accelerated partial breast irradiation; CTV = clinical target volume; D2cm3 = dose to 2 cm3 of the target; Dmax = maximum dose to the target; OAR = organs at risk; PTV = planning target volume; Vx% = dose to x% of the target volume.