A comparison of volumetric modulated arc therapy and conventional intensity-modulated radiotherapy for frontal and temporal high-grade gliomas.

Volumetric modulated arc therapy (VMAT), the predecessor to Varian's RapidArc, is a novel extension of intensity-modulated radiotherapy (IMRT) wherein the dose is delivered in a single gantry rotation while the multileaf collimator leaves are in motion. Leaf positions and the weights of field samples along the arc are directly optimized, and a variable dose rate is used. This planning study compared seven-field coplanar IMRT (cIMRT) with VMAT for high-grade gliomas that had planning target volumes (PTVs) overlapping organs at risk (OARs). 10 previously treated patients were replanned to 60 Gy in 30 fractions with cIMRT and VMAT using the following planning objectives: 98% of PTV covered by 95% isodose without violating OAR and hotspot dose constraints. Mean OAR doses were maximally decreased without reducing PTV coverage or violating hotspot constraints. We compared dose-volume histogram data, monitor units, and treatment times. There was equivalent PTV coverage, homogeneity, and conformality. VMAT significantly reduced maximum and mean retinal, lens, and contralateral optic nerve doses compared with IMRT (p < 0.05). Brainstem, chiasm, and ipsilateral optic nerve doses were similar. For 2-Gy fractions, mean monitor units were as follows: cIMRT = 789 +/- 112 and VMAT = 363 +/- 45 (relative reduction 54%, p = 0.002), and mean treatment times (min) were as follows: cIMRT = 5.1 +/- 0.4 and VMAT = 1.8 +/- 0.1 (relative reduction 65%, p = 0.002). Compared with cIMRT, VMAT achieved equal or better PTV coverage and OAR sparing while using fewer monitor units and less time to treat high-grade gliomas.

Shaffer R ，Nichol AM ，Vollans E ，Fong M ，Nakano S ，Moiseenko V ，Schmuland M ，Ma R ，McKenzie M ，Otto K ... -  《-》

Volumetric modulated Arc therapy and conventional intensity-modulated radiotherapy for simultaneous maximal intraprostatic boost: a planning comparison study.

Shaffer R ，Morris WJ ，Moiseenko V ，Welsh M ，Crumley C ，Nakano S ，Schmuland M ，Pickles T ，Otto K ... -  《-》

Volumetric modulated arc therapy improves dosimetry and reduces treatment time compared to conventional intensity-modulated radiotherapy for locoregional radiotherapy of left-sided breast cancer and internal mammary nodes.

Popescu CC ，Olivotto IA ，Beckham WA ，Ansbacher W ，Zavgorodni S ，Shaffer R ，Wai ES ，Otto K ... -  《-》

Volumetric modulated arc therapy: planning and evaluation for prostate cancer cases.

Zhang P ，Happersett L ，Hunt M ，Jackson A ，Zelefsky M ，Mageras G ... -  《-》

Single Arc Volumetric Modulated Arc Therapy of head and neck cancer.

The quality of Volumetric Modulated Arc Therapy (VMAT) plans is highly dependent on the performance of the optimization algorithm used. Recently new algorithms have become available which are capable of generating VMAT plans for Elekta accelerators. The VMAT algorithm in Pinnacle is named SmartArc and its capability to generate treatment plans for head and neck cancer was tested. Twenty-five patients with oropharyngeal or hypopharyngeal carcinoma, previously treated with IMRT by means of Pinnacle and Elekta accelerators, were replanned with single arc VMAT. The VMAT planning objectives were to achieve clinical target coverage and sparing of the organs at risk (OAR). Comparison with the original clinically used IMRT was made by evaluating (1) dose-volume histograms (DVHs) for PTVs, (2) DVHs for OARs, (3) delivery time and monitor units (MU), and (4) treatment accuracy. Equivalent or superior target coverage and sparing of OARs were achieved with VMAT compared to IMRT. Volumes in the healthy tissues receiving between 17.3 Gy and 49.4 Gy were significantly reduced and the conformity (CI(95%)) of the elective PTV was improved from 1.7 with IMRT to 1.6 with VMAT. Compared to step-and-shoot IMRT, VMAT reduced the number of MUs by 8.5% to 460+/-63 MUs per fraction, and delivered on an Elekta Synergy accelerator, the treatment time was on average reduced by 35% to 241 +/- 16s. In Delta4 measurements of the VMAT treatments, 99.6 +/- 0.5% of the detector points passed a 3 mm and 3% gamma criterion, identical to the results of IMRT. The target coverages obtained in the IMRT and VMAT plans were found to be very similar. SmartArc generated single arc VMAT plans with equivalent or better target coverage and sparing of OARs compared to IMRT, while both delivery time and MUs were decreased. Very good dose accuracy results were obtained delivering the plans on an Elekta accelerator.

Bertelsen A ，Hansen CR ，Johansen J ，Brink C ... -  《-》