High‐precision GAFCHROMIC EBT film‐based absolute clinical dosimetry using a standard flatbed scanner without the use of a scanner non‐uniformity correction

Abstract

To report a study of the use of GAFCHROMIC EBT radiochromic film (RCF) digitized with a commercially available flatbed document scanner for accurate and reliable all‐purpose two‐dimensional (2D) absolute dosimetry within a clinical environment. We used a simplified methodology that yields high‐precision dosimetry measurements without significant postirradiation correction. The Epson Expression 1680 Professional scanner and the Epson Expression 10000XL scanner were used to digitize the films. Both scanners were retrofitted with light‐diffusing glass to minimize the effects of Newton rings. Known doses were delivered to calibration films. Flat and wedge fields were irradiated with variable depth of solid water and 5 cm back scatter solid water. No particular scanner nonuniformity effect corrections or significant post‐scan image processing were carried out. The profiles were compared with CC04 ionization chamber profiles. The depth dose distribution was measured at a source‐to‐surface distance (SSD) of 100 cm with a field size of 10×10 cm2. Additionally, 22 IMRT fields were measured and evaluated using gamma index analysis. The overall accuracy of RCF with respect to CC04 was found to be 2%–4%. The overall accuracy of RCF was determined using the absolute mean of difference for all flat and wedge field profiles. For clinical IMRT fields, both scanners showed an overall gamma index passing rate greater than 90%. This work demonstrated that EBT films, in conjunction with a commercially available flatbed scanner, can be used as an accurate and precise absolute dosimeter. Both scanners showed that no significant scanner nonuniformity correction is necessary for accurate absolute dosimetry using the EBT films for field sizes smaller than or equal to 15×15 cm2.PACS number: 87.53.Bn

A prototype, glassless densitometer traceable to primary optical standards for quantitative radiochromic film dosimetry

“…This response is thought to be due to polymers having a preferred orientation 42 and is significant for coherent light, such as that used in the LDS. Film orientation dependence in the Epson has been well-characterized and has little or no dose-dependence; 43 so, for brevity, specific assessment of the orientation dependence of the Epson was not performed. To assess the degree of orientation dependence F.…”

Dosimetry of very high energy electrons (VHEE) for radiotherapy applications: using radiochromic film measurements and Monte Carlo simulations

“…Therefore, the film orientation in each image is recorded. The scanner response of EBT2 film is also sensitive to the position of the film on the scanner relative to the scan axis (Chung et al 2010), therefore a plastic template is used to position films in a reproducible central location in the middle of the scan window, where no correction of scan field uniformity is required. Ten preview scans are taken before the start of film scanning to allow the scanner temperature to stabilize and, thus, prevent any temperature-dependent response effects.…”

Quality assurance of asymmetric jaw alignment using 2D diode array

“…A 48-bit color charge-coupleddevice flat bed scanner (Epson Expression 10000XL, Epson America, Inc., CA) was used for EBT2 film digitization. 15 Each image was scanned ten times to reduce the noise 16 and saved in RGB 48-bit tagged-image-file format at the resolution of 300 dots per inch, and subsequently preprocessed with adaptive 2D Wiener filter to further reduce the image noise. The signal from the red channel was converted into the dose value.…”