title: The use of radiochromic film in treatment verification of dynamic stereotactic radiosurgery.
abstract: Standard silver-based films are usually too sensitive to be used as direct indicators of dose in dynamic radiosurgery because of optical saturation. This paper describes the use of a new radiochromic film to measure 6-MV radiosurgery doses and dose distributions in a head phantom. Dose calibration of the radiochromic film was performed in the range of 2.3-50.2 Gy using light of 632- and 530-nm wavelengths. Radiosurgery dose distributions were measured using the radiochromic film in a head phantom undergoing the same treatment as a patient, and were compared with the planned distributions. For an example case (nominal 2.0-cm-diam cone), film measurement verified the calculated dose distribution in one plane. The simple measurement technique described led to experimental uncertainties of +/- 0.1 cm for the 90% and 50% isodose lines, +/- 0.3 cm for the 20% line, and +/- 0.5 cm for the 10% line. Isocenter dose was measured with an uncertainty of +/- 3%. Refinements to the technique should allow more precise measurements. It is concluded that the radiochromic film, with some limitations, is a convenient and useful tool for dynamic radiosurgery quality assurance.
authors.affiliation: Toronto-Bayview Regional Cancer Centre, North York, Ontario, Canada.
authors.forename: R
authors.initials: R
authors.lastname: Ramani
authors.forename: A W
authors.initials: AW
authors.lastname: Lightstone
authors.forename: D L
authors.initials: DL
authors.lastname: Mason
authors.forename: P F
authors.initials: PF
authors.lastname: O'Brien
mesh_terms: D005373:Film Dosimetry / Q000295:instrumentation*; D006801:Humans; D016634:Radiosurgery / Q000295:instrumentation*; D013679:Technology, Radiologic