Technical Note: Initial characterization of the new EBT‐XD Gafchromic film. Issue 10 (14th September 2015)

• Record Type: Journal Article
• Authors: Grams, Michael P.; Gustafson, Jon M.; Long, Kenneth M.; de los Santos, Luis E. Fong
• Is Part Of: Medical physics. Volume 42:Issue 10(2015)
• Page Start: 5782
• Page End: 5786
• Publication Date: 2015-09-14
• Subjects: calibration -- dosimeters -- dosimetry -- planning -- radiation therapy; Dosimetry/exposure assessment -- Therapeutic applications, including brachytherapy -- Stereotactic radiosurgery -- Treatment planning -- Standards and calibration; Radiation therapy -- Testing or calibrating of apparatus or arrangements provided for in groups G01D1/00 to G01D15/00 -- Dosimeters -- Calibrating of instruments or apparatus -- Scintigraphy; lateral response artifact -- Gafchromic -- EBT‐XD; Image scanners -- Dosimetry -- Colorimetry -- Calibration -- Radiosurgery -- Active layer -- Medical treatment planning -- Spatial resolution -- Dynamic wedges; Medical physics -- Periodicals; Medical physics; Geneeskunde; Natuurkunde; Toepassingen; Biophysics; Periodicals; Periodicals; Electronic journals; 610.153
• DOI: 10.1118/1.4930058
• Languages: English
• ISSNs: 0094-2405

Abstract

Abstract : Purpose: To assess the dosimetric accuracy and energy dependence of the new EBT‐eX tendedD ose (XD) Gafchromic film and to compare the lateral response artifact (LRA) between EBT‐XD and EBT3 film. Methods: EBT3 and EBT‐XD calibration curves were created by exposing films to known doses from 0 to 3000 cGy using a 6 MV beam. To assess the accuracy and dynamic range of EBT‐XD, a 60° enhanced dynamic wedge (EDW) was used to deliver a dose range of approximately 200–2900 cGy. Comparison to treatment planning system (TPS) calculation was made using a gamma analysis with 2%/2 mm passing criteria. To assess and compare the LRA between EBT3 and EBT‐XD, 21 × 21 cm 2 open fields delivered doses of 1000, 2000, and 3000 cGy to both types of film. Films were placed at the center of the scanner, and ratios of measured to TPS predicted doses were calculated at 50 and 80 mm lateral from the scanner center in order to quantitatively assess the LRA. To evaluate the energy dependence of EBT‐XD film, seven known doses ranging from 400 to 3000 cGy were delivered using both 6 and 18 MV beams and the resulting optical densities (ODs) compared. Results: The gamma passing rate was 99.1% for the 6 MV EDW delivery. EBT‐XD film exhibited minimal LRA (<1%) up to 3000 cGy. In contrast, EBT3 demonstrated an under‐response of 11.3% and 22.7% at lateral positions of 50 and 80 mm, respectively, for the 3000 cGy exposure. Differences between ODs of the EBT‐XD films exposed to known doses from 6 to 18 MV beams were <0.8% suggesting minimal energy dependence throughout this energy range. Conclusions: The LRA of EBT‐XD is greatly reduced when compared to EBT3. This in combination with its accuracy from 0 to 3000 cGy and minimal energy dependence from 6 to 18 MV makes EBT‐XD film well suited for dosimetric measurements in high dose SRS/SBRT applications.