Table IV.
Dosage comparison between VMAT and IMRT plans in central lung cancer in which the target volume encompassing the mediastinal lymphatic drainage region.
| PTV 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 | 7,063.70±7.05a | 7,689.30±7.65 | 7,651.10±7.55 | 7,644.10±7.55 |
| PTV Dmin | 4,576.80±4.55 | 4,539.10±4.53 | 4,325.10±4.37 | 4,368.30±4.38 |
| PTV D100 (cGy) | 4,576.80±4.56 | 4,539.10±4.51 | 4,325.10±4.31 | 4,368.30±4.37 |
| PTV D mean (cGy) | 6,473.90±6.50a | 6,875.30±6.79 | 6,847.40±6.83 | 6,725.90±6.71 |
| PTV D98 (cGy) | 5,800.00±5.79 | 5,800.00±5.78 | 5,720.00±5.72 | 5,720.00±5.72 |
| PTV D95 (cGy) | 6,000.00±5.58 | 6,000.00±5.69 | 6,000.00±5.90 | 6,000.00±5.68 |
| PTV D50 (cGy) | 6,513.00±6.37a | 6,950.00±6.68 | 6,948.00±6.78 | 6,792.00±6.68c |
| PTV D2 (cGy) | 6,782.00±6.34a | 7,501.00±7.24 | 7,350.00±7.15 | 7,198.00±7.03c |
| Heart V30e (%) | 43.07±0.04 | 36.11±0.03 | 42.25±0.04 | 42.66±0.04c |
| Heart V40e (%) | 31.42±0.03 | 22.42±0.02 | 28.39±0.02 | 34.3±0.03c |
| Spinalcord D max (cGy) | 4,380.3±4.37a | 4,947.4±4.87 | 5,039.6±5.37 | 4,515.5±4.29c |
| Spinalcord D5 (cGy) | 3,763.00±3.39 | 4,098.00±4.01 | 4,175.00±4.12 | 3,976.00±3.97 |
| Lung all V5e (%) | 74.67±0.07 | 77.31±0.07 | 76.43±0.07 | 75.93±0.07 |
| Lung all V10e (%) | 63.72±0.06 | 70.70±0.07 | 67.66±0.06b | 64.11±0.06c |
| Lung all V20e (%) | 35.22±0.03 | 44.19±0.04 | 38.47±0.03b | 35.18±0.03c |
| Lung all V30e (%) | 20.54±0.02a | 22.06±0.02 | 23.02±0.02 | 21.51±0.02 |
| Lung all D mean (cGy) | 1,869.40±1.78 | 2,034.40±2.02 | 1,968.50±1.98 | 1,913.00±1.99c |
| Lung-ipsilateral D mean (cGy) | 33.77±0.03a | 37.08±0.03 | 41.03±0.03b | 37.26±0.03 |
| Lung-ipsilateral V5 (%) | 80.64±0.08 | 82.49±0.08 | 80.57±0.08 | 80.69±0.08 |
| Lung-ipsilateral V10 (%) | 75.11±0.07 | 75.91±0.07 | 73.95±0.07 | 75.55±0.07 |
| Lung-ipsilateral V20 (%) | 54.19±0.05 | 58.49±0.05 | 58.27±0.05 | 54.60±0.05 |
| Lung-ipsilateral V30 (%) | 33.77±0.03a | 37.08±0.03 | 41.03±0.03 | 37.26±0.03 |
| Lung-contralateral D mean (cGy) | 1,483.70±1.37 | 1,751.90±1.67 | 1,540.60±1.56 | 1,446.40±1.46 |
| Lung-contralateral V5 (%) | 80.07±0.08a | 86.34±0.08 | 86.47±0.08 | 84.96±0.08 |
| Lung-contralateral V10 | 62.49±0.06 | 78.42±0.07 | 73.59±0.07 | 63.57±0.06c |
| Lung-contralateral V20 | 20.67±0.02 | 36.62±0.03 | 23.61±0.02 | 20.11±0.02 |
| Lung-contralateral V30 | 9.60±0.00 | 9.42±0.00 | 7.18±0.00 | 7.95±0.00 |
| HI | 0.15±0.00a | 0.24±0.00 | 0.23±0.00 | 0.22±0.00 |
| CI | 0.70±0.00a | 0.70±0.00 | 0.61±0.00 | 0.58±0.00c |
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.