title: mARC vs. IMRT radiotherapy of the prostate with flat and flattening-filter-free beam energies.
abstract: BACKGROUND
  There as yet exists no systematic planning study investigating the novel mARC rotational radiotherapy technique, which is conceptually different from VMAT. We therefore present a planning study for prostate cancer, comparing mARC with IMRT treatment at the same linear accelerator equipped with flat and flattening-filter-free (FFF) photon energies.
  
  
  METHODS
  We retrospectively re-contoured and re-planned treatment plans for 10 consecutive prostate cancer patients. Plans were created for a Siemens Artiste linear accelerator with flat 6 MV and FFF 7 MV photons, using the Prowess Panther treatment planning system. mARC and IMRT plans were compared with each other considering indices for plan quality and dose to organs at risk. All plans were exported to the machine and irradiated while measuring scattered dose by thermoluminescent dosimeters placed on an anthropomorphic phantom. Treatment times were also measured and compared.
  
  
  RESULTS
  All plans were found acceptable for treatment. There was no marked preference for either technique or energy from the point of view of target coverage and dose to organs at risk. Scattered dose was significantly decreased by the use of FFF energies. While mARC and IMRT plans were of very similar overall quality, treatment time could be markedly decreased both by the use of mARC and FFF energy.
  
  
  CONCLUSIONS
  Highly conformal treatment plans could be created both by the use of flat 6 MV and FFF 7 MV energy, using IMRT or mARC. For all practical purposes, the FFF 7 MV energy and mARC plans are acceptable for treatment, a combination of both allowing a drastic reduction in treatment time from over 5 minutes to about half this value.
authors.affiliation: Department of Radiotherapy, Saarland University Medical Center, Kirrberger Str. Geb. 6.5, 66421, Homburg, Germany. yvonne.dzierma@uks.eu.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Dzierma
authors.affiliation: Department of Radiotherapy, Saarland University Medical Center, Kirrberger Str. Geb. 6.5, 66421, Homburg, Germany. rine.bell@gmx.de.
authors.forename: Katharina
authors.initials: K
authors.lastname: Bell
authors.affiliation: Department of Radiotherapy, Saarland University Medical Center, Kirrberger Str. Geb. 6.5, 66421, Homburg, Germany. jan.palm@uks.eu.
authors.forename: Jan
authors.initials: J
authors.lastname: Palm
authors.affiliation: Department of Radiotherapy, Saarland University Medical Center, Kirrberger Str. Geb. 6.5, 66421, Homburg, Germany. frank.nuesken@uks.eu.
authors.forename: Frank
authors.initials: F
authors.lastname: Nuesken
authors.affiliation: Department of Radiotherapy, Saarland University Medical Center, Kirrberger Str. Geb. 6.5, 66421, Homburg, Germany. norbert.licht@uks.eu.
authors.forename: Norbert
authors.initials: N
authors.lastname: Licht
authors.affiliation: Department of Radiotherapy, Saarland University Medical Center, Kirrberger Str. Geb. 6.5, 66421, Homburg, Germany. christian.ruebe@uks.eu.
authors.forename: Christian
authors.initials: C
authors.lastname: Rübe
mesh_terms: D000368:Aged; D006801:Humans; D008297:Male; D008875:Middle Aged; D058958:Organs at Risk; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*