Table III.
Dosage comparison between VMAT and IMRT plans in central lung cancer in which the target volume does not encompass the mediastinal lymphatic drainage region.
| PTV not encompassing the mediastinal lymphatic drainage region in central lung cancer | IMRT (mean ± SD) | SA-VMAT (mean ± SD) | PA-VMAT (mean ± SD) | 2PA-VMAT (mean ± SD) |
|---|---|---|---|---|
| PTV Dmax | 6,620.50±6.55 | 6,932.80±6.67 | 7,015.60±7.05 | 6,594.00±6.56 |
| PTV Dmin | 5,192.20±5.55 | 5,012.90±5.05 | 4,897.80±4.87 | 5,164.50±5.11 |
| PTV D100 (cGy) | 5,192.20±5.09 | 5,012.90±5.00 | 4,897.80±4.79 | 5,164.50±5.09 |
| PTV D mean (cGy) | 6,222.90±6.21 | 6,506.90±6.50 | 6,573.30±6.53 | 6,191.60±6.09c |
| PTV D98 (cGy) | 5,800.00±5.79 | 5,770.00±5.78 | 5,700.00±5.71 | 5,820.00±5.88 |
| PTV D95 (cGy) | 6,000.00±5.58 | 6,000.00±5.59 | 6,000.00±5.61 | 6,000.00±5.63 |
| PTV D50 (cGy) | 6,232.00±6.33 | 6,232.00±6.35 | 6,647.00±6.65 | 6,203.00±6.22 |
| PTV D2 (cGy) | 6,459.00±6.49 | 6,788.00±6.95 | 6,901.00±6.92 | 6,397.00±6.41 |
| Heart V30e (%) | 14.85±0.02 | 16.00±0.02 | 25.01±0.02b | 11.63±0.02c |
| Heart V40e (%) | 5.70±0.02 | 6.75±0.02 | 6.58±0.02 | 5.20±0.02 |
| Spinalcord D max (cGy) | 4,009.60±4.02a | 4,389.30±4.02 | 4,297.70±4.02 | 3,796.00±3.72c |
| Spinalcord D5 (cGy) | 2,997.00±2.82 | 3,300.00±3.12 | 3,285.00±3.13 | 3,083.00±3.07 |
| Lung all V5e (%) | 49.59±0.04 | 50.14±0.05 | 49.82±0.05 | 50.03±0.05 |
| Lung all V10e (%) | 27.66±0.02 | 33.3±0.03 | 31.89±0.03 | 28.23±0.02 |
| Lung all V20e (%) | 14.83±0.01 | 15.25±0.01 | 15.28±0.02 | 15.01±0.02 |
| Lung all V30e (%) | 11.90±0.01 | 11.70±0.01 | 11.99±0.01 | 12.17±0.01 |
| Lung all D mean (cGy) | 1,071.10±1.02 | 1,122.40±1.01 | 1,136.00±1.01 | 1,083.70±1.02 |
| Lung-ipsilateral D mean (cGy) | 1,843.80±1.71 | 1,892.50±1.79 | 1,918.20±1.91 | 1,873.50±1.81 |
| Lung-ipsilateral V5 (%) | 53.72±0.05 | 53.68±0.04 | 52.36±0.04 | 52.76±0.04 |
| Lung-ipsilateral V10 (%) | 47.45±0.04 | 48.38±0.04 | 47.69±0.04 | 47.51±0.04 |
| Lung-ipsilateral V20 (%) | 33.38±0.03 | 34.74±0.03 | 34.59±0.03 | 34.73±0.03 |
| Lung-ipsilateral V30 (%) | 27.54±0.02 | 27.08±0.02 | 27.76±0.02 | 28.17±0.02 |
| Lung-contralateral D mean (cGy) | 479.90±0.46 | 531.20±0.52 | 537.00±0.53 | 481.20±0.47c |
| Lung-contralateral V5 (%) | 46.05±0.04 | 46.97±0.04 | 47.62±0.04 | 47.72±0.04 |
| Lung-contralateral V10 | 12.43±0.01 | 21.42±0.02 | 19.77±0.01 | 13.61±0.01c |
| Lung-contralateral V20 | 0.72±0.00 | 0.43±0.00 | 0.60±0.00 | 0.00±0.00 |
| Lung-contralateral V30 | 0.00±0.00 | 0.00±0.00 | 0.00±0.00 | 0.00±0.00 |
| HI | 0.11±0.00 | 0.16±0.00 | 0.18±0.00 | 0.09±0.00 |
| CI | 0.66±0.00 | 0.51±0.00 | 0.49±0.00 | 0.70±0.00 |
a
P<0.05 compared with 2PA-VMAT plan
b
P<0.05 compared with SA-VMAT plan
c
P<0.05 compared with SA-VMAT plan. IMRT, intensity-modulated radiation therapy; VMAT, volumetric modulated arc therapy; SA, single arc; PA, partial arc; 2PA, double partial arc; SD, standard deviation; PTV, planning target volume; cGy, centigray; HI, homogeneity index; CI, conformity index.