title: The accuracy of dynamic wedge dose computation in the ADAC Pinnacle RTP system.
abstract: The nonphysical wedge is a modality that uses computer-controlled jaw motion to generate wedge-shaped dose distributions. There are Varian enhanced dynamic wedges (EDWs) and Siemens virtual wedges (VWs). We recently commissioned dynamic wedges on both Varian and Siemens LINACs. The beam data, acquired with a Wellhofer chamber array and a Sun Nuclear profiler, are used for modeling in the ADAC Pinnacle system. As recommended by ADAC, only a limited number of beam data is measured and used for beam modeling. Therefore, the dose distributions of dynamic wedges generated by Pinnacle must be examined. Following the commissioning of the dynamic wedges, we used Pinnacle to generate a number of dose distributions with different energies, wedge angles, field sizes, and depths. The computed data from Pinnacle are then compared with the measured data. The deviations of the output factor in all square and rectangular fields are mostly within 2.0% for both EDW and VW. For asymmetric fields, the deviations are within 3%. However, exceptions of differences more than 3% have been found in a larger field and large wedge combinations. The precision of the beam profiles generated by Pinnacle is also evaluated. As a result of this investigation, we present a scope of quality assurance tests that are necessary to ensure acceptable consistency between the delivered dose and the associated treatment plan when dynamic wedges are applied.
authors.affiliation: Radiation Oncology Department, University of Miami, School of Medicine, 1475 N.W. 12th Avenue, Miami, Florida 33136, USA. huashao@hotmail.com
authors.forename: H
authors.initials: H
authors.lastname: Shao
authors.forename: X
authors.initials: X
authors.lastname: Wu
authors.forename: C
authors.initials: C
authors.lastname: Luo
authors.forename: A
authors.initials: A
authors.lastname: Crooks
authors.forename: A
authors.initials: A
authors.lastname: Bernstein
authors.forename: A
authors.initials: A
authors.lastname: Markoe
mesh_terms: D019544:Equipment Failure Analysis; D010315:Particle Accelerators / Q000295:instrumentation*; D011785:Quality Assurance, Health Care / Q000379:methods*; D011874:Radiometry / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D011881:Radiotherapy, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal / Q000295:instrumentation* / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012984:Software; D012986:Software Validation
references.citation: Phys Med Biol. 1998 Sep;43(9):2651-63
references.pmid: 9755952
references.citation: Med Dosim. 2000 Summer;25(2):81-6
references.pmid: 10856686
references.citation: Med Phys. 1998 Aug;25(8):1411-8
references.pmid: 9725127
references.citation: Med Phys. 2000 Oct;27(10):2267-77
references.pmid: 11099193
references.citation: Med Phys. 1978 Sep-Oct;5(5):426-9
references.pmid: 101760
references.citation: Phys Med Biol. 1996 Sep;41(9):1691-704
references.pmid: 8884906
references.citation: Med Dosim. 1997 Fall;22(3):177-83
references.pmid: 9307947
references.citation: Med Phys. 1998 Jan;25(1):64-70
references.pmid: 9472827
references.citation: Med Phys. 2001 Feb;28(2):174-7
references.pmid: 11243340
references.citation: Med Phys. 2000 Jul;27(7):1635-43
references.pmid: 10947267
references.citation: Med Dosim. 1999 Summer;24(2):145-53
references.pmid: 10379513