Table 3.
Dosimetric comparisons of OARs between RapidArc and HT plans.
| OAR | Dose Parameter | RapidArc | HT | P-value | ||
|---|---|---|---|---|---|---|
| Average (SD) | Average (SD) | |||||
| Spinal Cord | Dmax (cGy) | 3603 | (368) | 3412 | (149) | NS |
| D1cc (cGy) | 3331 | (400) | 3240 | (131) | NS | |
| D0.1cc (cGy) | 3429 | (408) | 3347 | (132) | NS | |
| Brain Stem | Dmax (cGy) | 4965 | (130) | 4912 | (103) | NS |
| D1cc (cGy) | 4524 | (146) | 4304 | (179) | 0.012 | |
| D0.1cc (cGy) | 4767 | (149) | 4684 | (151) | NS | |
| Optic Chiasm | Dmax (cGy) | 3282 | (1436) | 4829 | (735) | <0.001 |
| D2 (cGy) | 3003 | (1220) | 4763 | (736) | <0.001 | |
| Optic Nerve I | Dmax (cGy) | 2745 | (1728) | 4906 | (1025) | <0.001 |
| D2 (cGy) | 2352 | (1578) | 4822 | (989) | <0.001 | |
| Optic Nerve C | Dmax (cGy) | 3040 | (1595) | 4921 | (763) | <0.001 |
| D2 (cGy) | 2621 | (1419) | 4807 | (731) | <0.001 | |
| Temporal Lobe I | Dmax (cGy) | 6643 | (350) | 6447 | (285) | 0.015 |
| V60Gy (%) | 1.7 | (1.3) | 2.1 | (1.6) | NS | |
| Temporal Lobe C | Dmax (cGy) | 6512 | (101) | 6283 | (162) | 0.001 |
| V60Gy (%) | 1 | (0.5) | 1.1 | (0.6) | NS | |
| Lens I | Dmax (cGy) | 524 | (98) | 427 | (119) | 0.009 |
| D2 (cGy) | 505 | (93) | 400 | (94) | 0.002 | |
| Dmean (cGy) | 431 | (97) | 299 | (46) | <0.001 | |
| Lens C | Dmax (cGy) | 509 | (87) | 425 | (135) | 0.047 |
| D2 (cGy) | 492 | (86) | 391 | (100) | 0.005 | |
| Dmean (cGy) | 418 | (92) | 291 | (47) | <0.001 | |
| Parotid I | Dmean (cGy) | 4114 | (493) | 3636 | (514) | 0.002 |
| Dmedian (cGy) | 3791 | (618) | 3437 | (809) | NS | |
| V30Gy (%) | 70.4 | (13.9) | 54.8 | (9.8) | 0.009 | |
| Parotid C | Dmean (cGy) | 3909 | (431) | 3336 | (449) | <0.001 |
| Dmedian (cGy) | 3585 | (525) | 3033 | (658) | 0.018 | |
| V30Gy (%) | 67.3 | (12.7) | 48.2 | (9.6) | 0.005 | |
| Pituitary | Dmax (cGy) | 5548 | (1023) | 5786 | (521) | NS |
| Body | V15 Gy (%) | 32.1 | (5.2) | 40 | (15.1) | NS |
| V20 Gy (%) | 27.9 | (4.9) | 34.5 | (13.7) | NS | |
| V30 Gy (%) | 19.9 | (4.3) | 23.1 | (11) | NS | |
| V40 Gy (%) | 12.5 | (2.9) | 14.2 | (6.7) | NS | |
OAR: organ at risk; SD: standard deviation; Dmax: maximum point dose; D1cc: maximum dose encompassing 1cc of the structure; D0.1cc: maximum dose encompassing 0.1cc of the structure; D2: maximum dose encompassing 2% of the structure; Dmean: mean dose of the structure; Dmedian: median dose of the structure; V15,20,30,40,60 Gy: the relative volume of the structure receiving over 15,20,30,40,60Gy.