VMAT plus a few computer-optimized non-coplanar IMRT beams (VMAT+) tested for liver SBRT.
To propose a novel treatment approach, designated VMAT+, involving addition of <5 IMRT beams with computer-optimized non-coplanar orientations to VMAT, and evaluate it for liver Stereotactic Body Radiation Therapy (SBRT). VMAT+ is investigated as an alternative for (1) coplanar VMAT and (2) multi-beam non-coplanar treatment.



For fifteen patients with liver metastases, VMAT+ plans were compared with (1) dual-arc VMAT and (2) 25-beam, non-coplanar treatment with computer-optimized beam orientations (25-NCP). All plans were generated fully automatically for delivery of the highest feasible tumor Biologically Effective Dose (BED). OAR doses, intermediate-dose-spillage, dose-compactness, and measured delivery times were evaluated.



With VMAT+ the maximum achievable tumor BED was equal to that of 25-NCP. Conversely, VMAT resulted in a lower tumor BED in 5 patients. Compared to VMAT, VMAT+ yielded significant dose reductions in OARs. Intermediate-dose-spillage and dose-compactness were significantly improved by 9.8% and 17.3% (p≤0.002), respectively. Treatment times with VMAT+ were only enhanced by 4.1min on average, compared to VMAT (8.4min). Improvements in OAR sparing with 25-NCP, compared to VMAT+, were generally modest and/or statistically insignificant, while delivery times were on average 20.5min longer.



For liver SBRT, VMAT+ is equivalent to time-consuming treatment with 25 non-coplanar beams in terms of achievable tumor BED. Compared to VMAT, OAR sparing and intermediate-dose-spillage are significantly improved, with minor increase in delivery time.
Department of Radiation Oncology, Erasmus MC Cancer Institute, Rotterdam, The Netherlands. Electronic address: a.sharfo@erasmusmc.nl.
Abdul Wahab M
AW
Sharfo
Department of Radiation Oncology, Erasmus MC Cancer Institute, Rotterdam, The Netherlands.
Maarten L P
ML
Dirkx
Department of Radiation Oncology, Erasmus MC Cancer Institute, Rotterdam, The Netherlands.
Sebastiaan
S
Breedveld
Department of Radiation Oncology, Erasmus MC Cancer Institute, Rotterdam, The Netherlands.
Alejandra
A
Méndez Romero
Department of Radiation Oncology, Erasmus MC Cancer Institute, Rotterdam, The Netherlands.
Ben J M
BJ
Heijmen
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000532:radiotherapy* / Q000556:secondary; D008297:Male; D008875:Middle Aged; D016634:Radiosurgery / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D016896:Treatment Outcome
Automated planning; Beam angle optimization; IMRT; Liver SBRT; Non-coplanar; VMAT