Table 2 Target volume and OARs dosimetric parameters for vIMPT and SPArc
From: Feasibility study: spot-scanning proton arc therapy (SPArc) for left-sided whole breast radiotherapy
Structure | Value | SPArc | vIMPT | Absolute difference (vIMPT − SPArc) | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Planned | 4D dynamic dose | AUC | Planned | 4D dynamic dose | AUC | Planned | 4D dynamic dose | AUC | ||
ITV | D98(cGy) | 4256 | 4262.75 ± 3.62 | 64.5 ± 15.55 | 4256 | 4265.63 ± 7.89 | 64.5 ± 5.73 | – | 2.88 ± 9.89 (p = 0.438) | 0 ± 13.54 (p = 1) |
HI |  | 1.05 ± 0.01 | 1.05 ± 0.01 |  | 1.08 ± 0.02 | 1.07 ± 0.02 |  | 0.03 ± 0.02 (p = 0.005) | 0.03 ± 0.02 (p = 0.006) |  |
CI |  | 0.78 ± 0.06 | 0.79 ± 0.05 |  | 0.77 ± 0.06 | 0.77 ± 0.05 |  | − 0.02 ± 0.02 (p = 0.044) | − 0.02 ± 0.02 (p = 0.018) |  |
heart | D1(cGy) | 53.63 ± 18.19 | 56.88 ± 19.90 | 2.25 ± 0.89 | 110.38 ± 18.93 | 126.88 ± 26.25 | 4.00 ± 1.51 | 56.75 ± 34.08 (p = 0.001) | 70.00 ± 32.14 (p < 0.001) | 1.75 ± 1.39 (p = 0.009) |
|  | Mean Dose(cGy) | 4.5 ± 2.33 | 4.75 ± 2.31 |  | 6.38 ± 2.13 | 6.75 ± 2.05 |  | 1.88 ± 2.10 (p = 0.04) | 2.00 ± 2.07 (p = 0.029) |  |
LAD | D1(cGy) | 82.25 ± 37.38 | 87.38 ± 40.29 | 9.88 ± 3.68 | 170.38 ± 74.31 | 196.5 ± 61.57 | 21.25 ± 10.35 | 88.13 ± 49.66 (p = 0.001) | 109.13 ± 57.17 (p = 0.001) | 11.38 ± 9.29 (p = 0.01) |
contralateral breast | Mean Dose(cGy) | 18.5 ± 7.07 | 19.75 ± 8.01 | 4.75 ± 2.31 | 12.13 ± 2.70 | 11.88 ± 3.40 | 3.63 ± 2.45 | − 6.37 ± 5.89 (p = 0.011) | − 7.88 ± 6.73 (p = 0.013) | − 1.13 ± 2.53 (p = 0.249) |
ipsilateral lung | V500(cGy) | 16.77 ± 7.18 | 16.63 ± 7.13 | 122.63 ± 38.26 | 25.56 ± 5.95 | 25.73 ± 5.27 | 168.25 ± 29.05 | 8.79 ± 5.25 (p = 0.001) | 9.11 ± 5.28 (p = 0.002) | 45.63 ± 21.54 (p = 0.001) |
|  | V2000(cGy) | 3.07 ± 2.17 | 3.06 ± 2.12 |  | 4.68 ± 1.78 | 4.67 ± 1.77 |  | 1.61 ± 1.03 (p = 0.003) | 1.61 ± 1.04 (p = 0.003) |  |
|  | Mean dose(cGy) | 282.75 ± 128.73 | 280.29 ± 127.59 |  | 395.38 ± 91.19 | 400.69 ± 94.82 |  | 112.63 ± 88.06 (p = 0.009) | 120.40 ± 77.92 (p = 0.003) |  |
Skin3mm | D1(cGy) | 4395.63 ± 98.35 | 4386.25 ± 96.62 | 85.5 ± 11.71 | 4411.63 ± 72.03 | 4402.5 ± 107.87 | 81.25 ± 27.73 | 16.00 ± 113.86 (p = 0.043) | 16.25 ± 113.92 (p = 0.05) | − 4.25 ± 21.10 (p = 0.587) |
|  | Mean Dose(cGy) | 3999.38 ± 120.57 | 3992 ± 108.02 |  | 4104.25 ± 110.34 | 4097.75 ± 90.84 |  | 104.87 ± 115.17 (p = 0.039) | 105.75 ± 112.03 (p = 0.032) |  |