title: Quality assurance of RapidArc in clinical practice using portal dosimetry.
abstract: OBJECTIVE
  Quality assurance data from five centres were analysed to assess the reliability of RapidArc radiotherapy delivery in terms of machine and dosimetric performance.
  
  
  METHODS
  A large group of patients was treated with RapidArc radiotherapy and treatment data recorded. Machine quality assurance was performed according to Ling et al (Int J Radiat Oncol Biol Phys 2008;72:575-81). In addition, treatment to a typical clinical case was delivered biweekly as a constancy check. Pre-treatment dosimetric validation of plan delivery was performed for each patient. All measurements and computations were performed at the depth of the maximum dose in water according to the GLAaS method using electronic portal imaging device measurements. Evaluation was carried out according to a gamma agreement index (GAI, the percentage of field area passing the test); the threshold dose difference was 3% and the threshold distance to agreement was 3 mm.
  
  
  RESULTS
  A total of 275 patients (395 arcs) were included in the study. Mean delivery parameters were 31.0±20.0° (collimator angle), 4.7±0.5° s(-1) (gantry speed), 343±134 MU min(-1) (dose rate) and 1.6±1.4 min (beam-on time) for prescription doses ranging from 1.8 to 16.7 Gy/fraction. Mean deviations from the baseline dose rate and gantry speed ranged from -0.61% to 1.75%. Mean deviations from the baseline for leaf speed variation ranged from -0.73% to 0.41%. The mean GAI of repeated clinical fields was 99.2±0.2%. GAI varied from 84.7% to 100%; the mean across all patients was 97.1±2.4%.
  
  
  CONCLUSIONS
  RapidArc can provide a reliable and accurate delivery of radiotherapy for a variety of clinical conditions.
authors: Oncology Institute of Southern Switzerland, Bellinzona, Switzerland.
authors: A
authors: A
authors: Fogliata
authors: A
authors: A
authors: Clivio
authors: P
authors: P
authors: Fenoglietto
authors: J
authors: J
authors: Hrbacek
authors: S
authors: S
authors: Kloeck
authors: P
authors: P
authors: Lattuada
authors: P
authors: P
authors: Mancosu
authors: G
authors: G
authors: Nicolini
authors: E
authors: E
authors: Parietti
authors: G
authors: G
authors: Urso
authors: E
authors: E
authors: Vanetti
authors: L
authors: L
authors: Cozzi
references: Radiother Oncol. 2008 Dec;89(3):254-62
references: 18760851
references: Med Phys. 2006 Aug;33(8):2839-51
references: 16964860
references: Med Phys. 1998 May;25(5):656-61
references: 9608475
references: Int J Radiat Oncol Biol Phys. 2009 May 1;74(1):252-9
references: 19362244
references: Int J Radiat Oncol Biol Phys. 2008 Oct 1;72(2):575-81
references: 18793960
references: Radiat Oncol. 2008 Sep 09;3:24
references: 18782447
references: Acta Oncol. 2009;48(8):1193-7
references: 19863228
references: Radiother Oncol. 2008 Dec;89(3):330-7
references: 18701175
references: Int J Radiat Oncol Biol Phys. 2009 Dec 1;75(5):1570-7
references: 19880261
references: Med Phys. 2008 Jun;35(6):2300-7
references: 18649462
references: Radiother Oncol. 2009 Jul;92(1):111-7
references: 19157609
references: Med Phys. 2008 Jan;35(1):310-7
references: 18293586
references: Acta Oncol. 2009;48(2):185-91
references: 18777411
references: Radiat Oncol. 2008 May 21;3:14
references: 18495005
references: Med Phys. 2008 Feb;35(2):464-72
references: 18383666
references: Radiother Oncol. 2009 Jul;92(1):118-24
references: 19181409
references: Int J Radiat Oncol Biol Phys. 2009 Jun 1;74(2):610-5
references: 19427560
references: Int J Radiat Oncol Biol Phys. 2009 Feb 1;73(2):537-45
references: 19147018
references: Radiat Oncol. 2007 Nov 23;2:42
references: 18036217
references: Int J Radiat Oncol Biol Phys. 2008;71(1 Suppl):S80-4
references: 18406944
references: Radiother Oncol. 2008 Nov;89(2):180-91
references: 18692929
references: Acta Oncol. 2009;48(2):227-32
references: 18855157
references: Int J Radiat Oncol Biol Phys. 2009 Sep 1;75(1):253-9
references: 19577856