title: A dosimetric comparison of volumetric modulated arc therapy (VMAT) and non-coplanar intensity modulated radiotherapy (IMRT) for nasal cavity and paranasal sinus cancer.
abstract: BACKGROUND
  To compare dosimetric parameters of volumetric modulated arc therapy (VMAT) and non-coplanar intensity modulated radiotherapy (IMRT) for nasal cavity and paranasal sinus cancer with regard to the coverage of planning target volume (PTV) and the sparing of organs at risk (OAR).
  
  
  METHODS
  Ten patients with nasal cavity or paranasal sinus cancer were re-planned by VMAT (two-arc) plan and non-coplanar IMRT (7-, 11-, and 15-beam) plans. Planning objectives were to deliver 60 Gy in 30 fractions to 95% of PTV, with maximum doses (D(max)) of <50 Gy to the optic nerves, optic chiasm, and brainstem, <40 Gy to the eyes and <10 Gy to the lenses. The target mean dose (D(mean)) to the parotid glands was <25 Gy, and no constraints were applied to the lacrimal glands. Planning was optimized to minimized doses to OAR without compromising coverage of the PTV. VMAT and three non-coplanar IMRT (7-, 11-, and 15-beam) plans were compared using the heterogeneity and conformity indices (HI and CI) of the PTV, D(max) and D(mean) of the OAR, treatment delivery time, and monitor units (MUs).
  
  
  RESULTS
  The HI and CI of VMAT plan were superior to those of the 7-, 11-, and 15-beam non-coplanar IMRT. VMAT and non-coplanar IMRT (7-, 11-, and 15-beam) showed equivalent sparing effects for the optic nerves, optic chiasm, brainstem, and parotid glands. For the eyes and lenses, VMAT achieved equivalent or better sparing effects when compared with the non-coplanar IMRT plans. VMAT showed lower MUs and reduced treatment delivery time when compared with non-coplanar IMRT.
  
  
  CONCLUSIONS
  In 10 patients with nasal cavity or paranasal sinus cancer, a VMAT plan provided better homogeneity and conformity for PTV than non-coplanar IMRT plans, with a shorter treatment delivery time, while achieving equal or better OAR-sparing effects and using fewer MUs.
authors.forename: Yuri
authors.initials: Y
authors.lastname: Jeong
authors.affiliation: Department of Radiation Oncology, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro-43-gil, Songpa-gu, Seoul 138-736, Republic of Korea. lsw@amc.seoul.kr.
authors.forename: Sang-wook
authors.initials: SW
authors.lastname: Lee
authors.forename: Jungwon
authors.initials: J
authors.lastname: Kwak
authors.forename: Ilsung
authors.initials: I
authors.lastname: Cho
authors.forename: Sang Min
authors.initials: SM
authors.lastname: Yoon
authors.forename: Jong Hoon
authors.initials: JH
authors.lastname: Kim
authors.forename: Jin-Hong
authors.initials: JH
authors.lastname: Park
authors.forename: Eun Kyung
authors.initials: EK
authors.lastname: Choi
authors.forename: Si Yeol
authors.initials: SY
authors.lastname: Song
authors.forename: Young Seok
authors.initials: YS
authors.lastname: Kim
authors.forename: Su Ssan
authors.initials: SS
authors.lastname: Kim
authors.forename: Ji Hyeon
authors.initials: JH
authors.lastname: Joo
authors.forename: Seung Do
authors.initials: SD
authors.lastname: Ahn
mesh_terms: D005123:Eye / Q000528:radiation effects; D006801:Humans; D007765:Lacrimal Apparatus / Q000528:radiation effects; D009296:Nasal Cavity / Q000528:radiation effects*; D009900:Optic Nerve / Q000528:radiation effects; D058958:Organs at Risk / Q000528:radiation effects; D010255:Paranasal Sinus Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D010256:Paranasal Sinuses / Q000473:pathology / Q000528:radiation effects; D010306:Parotid Gland / Q000528:radiation effects; D011874:Radiometry; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods*; D047368:Tumor Burden