title: A comparison of electronic portal dosimetry verification methods for use in stereotactic radiotherapy.
abstract: Three methods of transit dosimetry using Electronic Portal Imaging Devices (EPIDs) were investigated for use in routine in-vivo dosimetry for cranial stereotactic radiosurgery and radiotherapy. The approaches examined were (a) A full Monte Carlo (MC) simulation of radiation transport through the linear accelerator and patient; (b) Calculation of the expected fluence by a treatment planning system (TPS); (c) Point doses calculated along the central axis compared to doses calculated using parameters acquired using the EPID. A dosimetric comparison of each of the three methods predicted doses at the imager plane to within ±5% and a gamma comparison for the MC and TPS based approaches showed good agreement for a range of dose and distance to agreement criteria. The MC technique was most time consuming, followed by the TPS calculation with the point dose calculation significantly quicker than the other methods.
authors.affiliation: Physics Department, Velindre Cancer Centre, Velindre Road, Cardiff CF14 2TL, UK. Electronic address: tony.millin@wales.nhs.uk.
authors.forename: Anthony E
authors.initials: AE
authors.lastname: Millin
authors.affiliation: Physics Department, Velindre Cancer Centre, Velindre Road, Cardiff CF14 2TL, UK.
authors.forename: Rebecca S
authors.initials: RS
authors.lastname: Windle
authors.affiliation: Physics Department, Velindre Cancer Centre, Velindre Road, Cardiff CF14 2TL, UK.
authors.forename: D Geraint
authors.initials: DG
authors.lastname: Lewis
mesh_terms: D000465:Algorithms; D001921:Brain / Q000528:radiation effects; D002138:Calibration; D004867:Equipment Design; D006801:Humans; D009010:Monte Carlo Method; D010315:Particle Accelerators; D011785:Quality Assurance, Health Care; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods*; D016634:Radiosurgery / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods; D015203:Reproducibility of Results; D012886:Skull / Q000528:radiation effects
keywords: EPID; Portal dosimetry; Stereotactic radiotherapy