Table 5. Comparative planning studies in central nervous system tumours.
| Paper [ref] VMAT commercial system | Number of patients | Type + Dose | Comparison | PTV | OAR | MU per fraction | Treatment time per fraction |
| Fogliata et al [129] RapidArc | 12 | Acoustic neuroma, meningioma, pituitary adenoma | Non-coplanar IMRT (5−7F,SW) vs VMAT vs HT | VMAT and HT slightly better than IMRT for PTV coverage (D99%, D98%). VMAT and IMRT slightly better than HT for conformity | VMAT and IMRT better than HT at sparing OARs (brainstem, optic structures). VMAT and IMRT – lower integral dose to body compared with HT | ||
| Lagerwaard et al [130] RapidArc | 3 | Acoustic neuroma (radiosurgery single 12.5Gy) | VMAT (SA) vs 1DCA vs 5DCA | Similar PTV coverage. VMAT better than DCA for conformity | VMAT and 5DCA – similar maximum doses for cochlea, brainstem, trigeminal nerve (1DCA gave higher doses compared with VMAT and 5DCA). VMAT and 1DCA – smaller volume of normal brain receiving low dose radiation compared with 5DCA | VMAT, 2763−2869; 5DCA, 2483−2769 | VMAT, 4−5 min; 5DCA, 20 min |
| Wagner et al [132] RapidArc | 14 | High grade glioma | 3D-CRT (2−8F) vs IMRT (5−9F,SW) vs VMAT (SA) | IMRT better than VMAT and 3D-CRT for PTV coverage. 3D-CRT as good as IMRT and VMAT for coverage of PTVs distant from OAR but significantly inferior for PTVs close to OARs. VMAT slightly better than IMRT for conformity (both VMAT and IMRT better than CRT) | VMAT slightly better than IMRT and 3D-CRT for OAR sparing (chiasm, brainstem). VMAT – highest mean dose to normal brain and V5Gy of healthy tissue | VMAT, 321.1; IMRT, 587.8; CRT, 224 | VMAT 5× faster than IMRT; 1.2× faster than CRT |
| Shaffer et al [133] RapidArc | 10 | High grade glioma | IMRT (7F,SW) vs VMAT (SA) | Similar PTV coverage, conformity and homogeneity | VMAT better than IMRT at sparing lateralised OARs (retina, lens, optic nerves). No significant differences in sparing of centralised OARs (brainstem, chiasm). VMAT – higher mean dose to normal brain (by 12%) | VMAT, 363; IMRT, 789 | VMAT, 1.8 min; IMRT; 5.1 min |
| Lagerwaard et al [135] RapidArc | 8 | Brain metastases (1−5) | WBRT + SIB with VMAT 40Gy in 5 fractions (integrated plans) vs conventional WBRT + stereotactic boost 21Gy (summated plans) | Integrated plans (VMAT) significantly better than summated plans for conformity | Integrated plans (VMAT) – smaller volume of normal brain receiving 25−35Gy. Integrated plans (VMAT) – higher maximum dose to lenses | Integrated plans (VMAT), 1600 | Integrated plans (VMAT), 3 min |
| Ma et al [136] RapidArc | 10 | 2–4 brain metastases | IMRT (7F,SS) vs VMAT (SA) vs VMAT (DA) | Similar PTV coverage. DA VMAT slightly better than SA VMAT and IMRT for conformity and homogeneity | DA VMAT better than IMRT at sparing brainstem, optic nerves, lenses (lower maximum doses). VMAT – higher V5Gy healthy tissue, but lower V15Gy and V20Gy compared with IMRT | IMRT, 1944; VMAT (SA), 1199; VMAT (DA), 1387 | (Beam on time) IMRT, 6.5 min; VMAT (SA), 1.25 min; VMAT (DA), 2.5 min |
| Wu et al [139] RapidArc | 10 | Spinal metastases SBRT 16Gy single fraction | IMRT, (8−12F,SW) vs VMAT (SA) vs VMAT (DA) | Similar PTV coverage. DA VMAT better than SA VMAT and IMRT for conformity | IMRT better than VMAT for spinal cord sparing (significant difference for SA VMAT vs IMRT but not significant for DA VMAT vs IMRT) | VMAT (SA), 7730; VMAT(DA), 6317; IMRT, 8711 | VMAT, 7.9−8.6 min; IMRT, 15.9 min |
| Kuijper et al [140] RapidArc | 5 | Spinal metastases SBRT 16Gy Group 1: PTV = vertebral body only Group 2: PTV = entire vertebra | IMRT (7−9F,SW) vs VMAT (2−3 arcs) | Group 1: Similar and acceptable PTV coverage. VMAT better than IMRT for conformity; Group 2: Similar but inadequate PTV coverage. VMAT better than IMRT for conformity | Group 1: Similar OAR sparing; Group 2: VMAT slightly better than IMRT for spinal cord sparing | Group 1: VMAT, 7816; IMRT, 5660; Group 2: VMAT, 9019; IMRT, 9399 | Group 1: VMAT, 13.5 min; IMRT, 12.5 min; Group 2: VMAT, 16 min; IMRT, 19−20 min |
VMAT, volumetric modulated arc therapy; PTV, planning target volume; OAR, organs at risk; MU, monitor units; IMRT, intensity modulated radiotherapy; 5F, five field; 7F, seven field; 9F, nine field; 2F, two field; 8F, eight field; 12F, twelve field; SW, sliding window; SS, step-and-shoot; HT; helical tomotherapy; D99%, dose to 99% of volume; D98%, dose to 98% of volume; SA, single arc; DA, double arc; DCA, dynamic conformal arc; 3D-CRT, three-dimensional conformal radiotherapy; V5Gy, volume receiving ≥5Gy; WBRT, whole brain radiotherapy; SIB, simultaneous integrated boost; V15Gy, volume receiving ≥15Gy; V20Gy, volume receiving ≥20Gy; SBRT, stereotactic body radiotherapy.