title: Critical appraisal of volumetric-modulated arc therapy compared with electrons for the radiotherapy of cutaneous Kaposi's sarcoma of lower extremities with bone sparing.
abstract: OBJECTIVE
  To evaluate the use of volumetric-modulated arc therapy [VMAT, RapidArc® (RA); Varian Medical Systems, Palo Alto, CA] for the treatment of cutaneous Kaposi's sarcoma (KS) of lower extremities with adequate target coverage and high bone sparing, and to compare VMAT with electron beam therapy.
  
  
  METHODS
  10 patients were planned with either RA or electron beams. The dose was prescribed to 30 Gy, 10 fractions, to mean the planning target volume (PTV), and significant maximum dose to bone was limited to 30 Gy. Plans were designed for 6-MV photon beams for RA and 6 MeV for electrons. Dose distributions were computed with AcurosXB® (Varian Medical Systems) for photons and with a Monte Carlo algorithm for electrons.
  
  
  RESULTS
  V(90%) was 97.3±1.2 for RA plans and 78.2±2.6 for electrons; similarly, V(107%) was 2.5±2.2 and 37.7±3.4, respectively. RA met coverage criteria. Concerning bone sparing, D(2%) was 29.6±1.1 for RA and 31.0±2.4 for electrons. Although acceptable for bone involvement, pronounced target coverage violations were obtained for electron plans. Monitor units were similar for electrons and RA, although for the latter they increased when superior bone sparing was imposed. Delivery times were 12.1±4.0 min for electrons and 4.8±1.3 min for the most modulated RA plans.
  
  
  CONCLUSIONS
  High plan quality was shown for KS in the lower extremities using VMAT, and this might simplify their management in comparison with the more conventional usage of electrons, particularly in institutes with limited staff resources and heavy workloads.
  
  
  CONCLUSIONS
  VMAT is also dosimetrically extremely advantageous in a typology of treatments where electron beam therapy is mainly considered to be effective owing to the limited penetration of the beams.
authors: Medical Physics Unit, Radiotherapy Department, Oncology Institute of Southern Switzerland, Bellinzona, Switzerland. giorgia.nicolini@eoc.ch
authors: G
authors: G
authors: Nicolini
authors: S
authors: S
authors: Abraham
authors: A
authors: A
authors: Fogliata
authors: A
authors: A
authors: Jordaan
authors: A
authors: A
authors: Clivio
authors: E
authors: E
authors: Vanetti
authors: L
authors: L
authors: Cozzi
mesh_terms: D004583:Electrons / Q000627:therapeutic use*; D005529:Foot Bones / Q000528:radiation effects; D006801:Humans; D007867:Leg Bones / Q000528:radiation effects; D059351:Organ Sparing Treatments / Q000379:methods; D010347:Patient Care Planning; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012514:Sarcoma, Kaposi / Q000532:radiotherapy*; D012878:Skin Neoplasms / Q000532:radiotherapy*
references: Int J Radiat Oncol Biol Phys. 1991 Mar;20(3):419-22
references: 1995526
references: Radiother Oncol. 2011 Apr;99(1):79-85
references: 21421273
references: Med Phys. 2008 Jan;35(1):310-7
references: 18293586
references: Int J Radiat Oncol Biol Phys. 1991 Nov;21(6):1517-22
references: 1938561
references: Phys Med Biol. 2001 Feb;46(2):269-86
references: 11229714
references: J Natl Cancer Inst Monogr. 2001;(28):1-4
references: 11158199
references: Radiat Oncol. 2010 Sep 20;5:83
references: 20854661
references: Radiother Oncol. 1998 Jan;46(1):23-8
references: 9488123
references: Radiother Oncol. 2008 Aug;88(2):211-6
references: 18439694
references: Phys Med Biol. 1995 Apr;40(4):543-74
references: 7610114
references: Med Phys. 2011 Nov;38(11):5844-56
references: 22047348
references: J Clin Oncol. 1987 Jan;5(1):107-12
references: 2433407
references: Phys Med Biol. 2010 Feb 7;55(3):581-98
references: 20057008
references: Int J STD AIDS. 2006 Sep;17(9):571-8
references: 16942647
references: Med Dosim. 2010 Autumn;35(3):226-9
references: 19931036
references: Acta Oncol. 2013 Apr;52(3):545-52
references: 22671576
references: Acta Oncol. 1996;35(2):193-9
references: 8639315
references: Dermatology. 1997;195(1):40-2
references: 9267735
references: Int J Radiat Oncol Biol Phys. 1990 Sep;19(3):569-75
references: 2211205