Table 4.
Comparison of dosimetric parameters between techniques
| 9-field estimate minus tangential beamlet estimate |
Segmental estimate minus tangential beamlet estimate) |
Segmental blocked estimate minus tangential beamlet estimate |
||||
|---|---|---|---|---|---|---|
| Structure | Mean paired difference (SD) | p value | Mean paired difference (SD) | p value | Mean paired difference (SD) | p value |
| Normal tissues | ||||||
| Right lung | ||||||
| Mean dose Gy) | 2.46 (1.34) | 0.0003 | –0.18 (0.66) | 0.4119 | –0.28 (0.62) | 0.1886 |
| V2 (%) | 64.98 (16.24) | <0.0001 | –7.03 (13.05) | 0.1226 | –7.94 (13.16) | 0.0889 |
| V5 (%) | 9.19 (21.57) | 0.2107 | –1.63 (5.13) | 0.3408 | –1.75 (5.09) | 0.3055 |
| V10 (%) | 0.94 (4.18) | 0.4947 | –0.35 (0.96) | 0.2855 | –0.35 (0.96) | 0.2753 |
| Right breast/chest wall | ||||||
| Mean dose Gy) | 2.03 (0.83) | <0.0001 | 0.36 (0.34) | 0.0083 | 0.20 (0.34) | 0.1013 |
| V2 (%) | 48.38 (24.54) | 0.0002 | 1.22 (7.40) | 0.6159 | –1.44 (8.29) | 0.5963 |
| V5 (%) | 9.79 (8.42) | 0.0051 | 1.51 (1.27) | 0.0046 | 1.08 (1.20) | 0.0197 |
| V10 (%) | 0.09 (0.87) | 0.7601 | 0.72 (0.76) | 0.0151 | 0.57 (0.69) | 0.0291 |
| Left lung | ||||||
| Mean dose Gy) | 3.95 (2.05) | 0.0002 | 1.69 (2.18) | 0.0361 | –0.22 (1.80) | 0.7049 |
| V2 (%) | 24.81 (9.52) | <0.0001 | –6.89 (8.22) | 0.0264 | –9.34 (8.51) | 0.0070 |
| V5 (%) | 39.44 (8.94) | <0.0001 | –4.84 (10.27) | 0.1704 | –7.84 (9.97) | 0.0348 |
| V10 (%) | 25.32 (13.05) | 0.0002 | –3.69 (9.68) | 0.2589 | –6.71 (9.36) | 0.0495 |
| V20 (%) | 4.97 (4.21) | 0.0047 | 1.33 (4.39) | 0.3617 | –1.87 (3.87) | 0.1602 |
| V30 (%) | –2.26 (4.32) | 0.1325 | 5.75 (4.80) | 0.0043 | 2.22 (4.00) | 0.1127 |
| V40 (%) | –2.49 (5.27) | 0.1694 | 9.64 (5.74) | 0.0005 | 5.30 (4.95) | 0.0081 |
| V50 (%) | –1.17 (2.13) | 0.1156 | 5.99 (3.26) | 0.0003 | 1.76 (1.58) | 0.0064 |
| Heart | ||||||
| Mean dose Gy) | 4.58 (1.39) | <0.0001 | 1.51 (1.74) | 0.0225 | –0.69 (1.20) | 0.1029 |
| V2 (%) | 48.47 (31.77) | 0.0009 | –3.72 (26.12) | 0.6636 | –13.84 (25.08) | 0.1149 |
| V5 (%) | 70.02 (15.05) | <0.0001 | 2.32 (13.47) | 0.5998 | –6.75 (13.33) | 0.1439 |
| V10 (%) | 9.03 (7.73) | 0.0050 | 4.65 (4.79) | 0.0134 | –1.90 (3.37) | 0.1080 |
| V20 (%) | –0.09 (0.83) | 0.7481 | 4.43 (3.06) | 0.0013 | –0.37 (0.81) | 0.1856 |
| V30 (%) | –0.05 (0.17) | 0.4215 | 3.29 (2.36) | 0.0017 | –0.05 (0.17) | 0.3896 |
| LAD artery | ||||||
| Mean dose Gy) | 5.79 (2.20) | <0.0001 | 15.14 (8.34) | 0.0003 | 0.56 (2.61) | 0.5152 |
| Max dose to 1% volume (Gy) | 9.51 (6.65) | 0.0014 | 36.79 (14.31) | <0.0001 | 4.41 (6.81) | 0.0709 |
| Targets | ||||||
| Whole breast PTV | ||||||
| Mean dose (Gy) | 0.13 (1.47) | 0.7941 | 2.70 (1.92) | 0.0016 | 0.30 (1.36) | 0.5017 |
| D95 Gy) | 4.39 (5.10) | 0.0236 | 5.55 (5.43) | 0.0102 | –0.89 (5.28) | 0.6078 |
| Max dose to 1% volume (Gy) | –1.81 (1.51) | 0.0043 | 2.80 (1.75) | 0.0007 | 1.93 (1.46) | 0.0023 |
| V47.5 (%) | 2.27 (2.50) | 0.0183 | 4.08 (3.48) | 0.0049 | –0.58 (2.95) | 0.5514 |
| Internal Mammary region | ||||||
| Mean dose (Gy) | 4.17 (7.98) | 0.1332 | –3.45 (8.59) | 0.2360 | –5.52 (7.80) | 0.0520 |
| D95 (Gy) | 4.22 (10.70) | 0.2436 | –7.73 (13.05) | 0.0938 | –13.15 (11.26) | 0.0050 |
| Max dose to 1% volume (Gy) | 2.12 (5.41) | 0.2461 | –3.78 (7.24) | 0.1333 | –5.01 (6.82) | 0.0453 |
| V47.5 (%) | 15.28 (26.54) | 0.1019 | –7.04 (20.96) | 0.3158 | –18.20 (17.63) | 0.0098 |
| Supraclavicular region | ||||||
| Mean dose (Gy) | 0.57 (1.54) | 0.2717 | –0.67 (2.81) | 0.4692 | –0.65 (2.36) | 0.4064 |
| D95 (Gy) | –0.06 (3.17) | 0.9543 | 0.45 (4.42) | 0.7561 | –0.68 (3.75) | 0.5796 |
| Max dose to 1% volume (Gy) | –0.03 (3.14) | 0.9793 | –0.73 (3.47) | 0.5252 | –2.31 (3.54) | 0.0698 |
| Infraclavicular region | ||||||
| Mean dose (Gy) | 0.59 (1.88) | 0.3494 | –0.40 (2.57) | 0.6325 | –2.14 (2.72) | 0.0343 |
| D95 (Gy) | 0.11 (2.86) | 0.9092 | –3.02 (5.58) | 0.1210 | –5.29 (4.92) | 0.0078 |
| Max dose to 1% volume (Gy) | 0.19 (2.12) | 0.7820 | 0.19 (2.28) | 0.7908 | –1.83 (2.84) | 0.0719 |
| Boost Volume | ||||||
| Mean dose Gy) | –0.87 (1.75) | 0.1521 | 2.58 (2.01) | 0.0029 | 1.64 (2.09) | 0.0354 |
| D95 (Gy) | –0.86 (2.12) | 0.2328 | –0.30 (6.56) | 0.8874 | 0.93 (2.53) | 0.2752 |
| Max dose to 1% volume (Gy) | –1.31 (1.68) | 0.0352 | 2.87 (1.86) | 0.0009 | 1.90 (1.63) | 0.0050 |
| V47.5 (%) | –0.13 (1.34) | 0.7615 | 0.30 (0.97) | 0.3540 | 0.37 (0.88) | 0.2134 |
Abbreviations: V2 = percentage of the volume receiving 2 Gy or more, e.g., V5 is the percentage of the volume receiving 5 Gy or more, etc.; D95 = lowest dose received by at least 95% of the volume; SD = standard deviation.