Show simple item record

dc.contributor.authorO'Shea, Tuathan P.
dc.contributor.authorFoley, Mark J.
dc.identifier.citationO'Shea, TP,Sawkey, DL,Foley, MJ,Faddegon, BA (2010) 'Monte Carlo commissioning of clinical electron beams using large field measurements'. Physics In Medicine And Biology, 55 :4083-4105.en_US
dc.descriptionJournal articleen_US
dc.description.abstractMonte Carlo simulation can accurately calculate electron fluence at the patient surface and the resultant dose deposition if the initial source electron beam and linear accelerator treatment head geometry parameters are well characterized. A recent approach used large electron fields to extract these simulation parameters. This method took advantage of the absence of lower energy, widely scattered electrons from the applicator resulting in more accurate data. It is important to validate these simulation parameters for clinically relevant fields. In the current study, these simulation parameters are applied to fields collimated by applicators and inserts to perform a comprehensive validation. Measurements were performed on a Siemens Oncor linear accelerator for 6 MeV, 9 MeV, 12 MeV, 15 MeV, 18 MeV and 21 MeV electron beams and collimators ranging from an open 25 x 25 cm(2) applicator to a 10 x 10 cm(2) applicator with a 1 cm diameter cerrobend insert. Data were collected for inserts placed in four square applicators. Monte Carlo simulations were performed using EGSnrc/BEAMnrc. Source and geometry parameters were obtained from previous measurements and simulations with the maximum field size (40 x 40 cm(2)). The applicators were modelled using manufacturer specifications, confirmed by direct measurements. Cerrobend inserts were modelled based on calliper measurements. Monte Carlo-calculated percentage depth dose and off-axis profiles agreed with measurements to within the least restrictive of 2%/1 mm in most cases. For the largest applicator (25 x 25 cm(2)), and 18 MeV and 21 MeV beams, differences in dose profiles of 3% were observed. Calculated relative output factors were within 2% of those measured with an electron diode for fields 1.5 cm in diameter or larger. The disagreement for 1 cm diameter fields was up to 5%. For open applicators, simulations agreed with parallel plate chamber-measured relative output factors to 1%. This work has validated a recent methodology used to extract data on the electron source and treatment head from large electron fields, resulting in a reduction in the number of unknown parameters in treatment head simulation. Applicator and insert collimated electron fields were accurately simulated without adjusting these parameters. Results demonstrate that commissioning of electron beams based on large electron field measurements is a viable option.en_US
dc.publisherInstitute Of Physics (IOP Publishing)en_US
dc.relation.ispartofPhysics In Medicine And Biologyen
dc.rightsAttribution-NonCommercial-NoDerivs 3.0 Ireland
dc.subjectHigh-energy photonen_US
dc.subjectOutput factorsen_US
dc.subjectIonization chambersen_US
dc.subjectSource parametersen_US
dc.titleMonte Carlo commissioning of clinical electron beams using large field measurementsen_US
dc.identifier.doiDOI 10.1088/0031-9155/55/14/009
dc.local.contactMark Foley, School Of Physics, Nui Galway. 5383 Email:

Files in this item


This item appears in the following Collection(s)

Show simple item record

Attribution-NonCommercial-NoDerivs 3.0 Ireland
Except where otherwise noted, this item's license is described as Attribution-NonCommercial-NoDerivs 3.0 Ireland