|
Features:
• Measure with economic flatbed color scanner
• Dose range 1cGy to 10Gy (measure in red color channel); up to 40Gy measured in green color channel
• Active layer incorporates a yellow dye
• Reference baseline for film response
• Decreases UV/light sensitivity by 10X
• Use the response in the blue color channel to adjust for small response differences over the area of a film
• Develops in real time- There is no post-exposure treatment
• Density changes stabilize rapidly after exposure
• Energy-dependence; <10% response difference from 60keV into the MV range
• Minimizes concerns about the effects of scattered radiation
• Near tissue equivalent
• High spatial resolution- can resolve features to at least 100µm
• Handle in room light- eliminate the need for a darkroom
• Can be cut to any size and shaped to contours
• Water resistant- can be immersed for hours in water phantoms
• Stable at temperatures up to 60°C
• Shelf life of 2 years at room ambient temperature
Energy Independence of Gafchromic® EBT Dosimetry Film
Gafchromic® EBT radiochromic film has been designed to measure absorbed dose from high-energy radiation used in IMRT. The response to photons has been found to be energy-independent in the MeV range and measurements at lower energies show that the response changes by only a few percent, even down to 30keV.
Gafchromic® EBT2 dosimetry film incorporates a number of features that are improvements over the original version (Gafchromic® EBT), but uses exactly the same active component. The new film incorporates a yellow marker dye that provides two benefits. Firstly, if EBT2 film is measured on a color scanner, the signal provided by the dye in the blue color channel can be used to improve dose accuracy by adjusting for small differences in response over the area of the film. Secondly, the yellow dye protects the active layer from UV exposure and visible light, reducing the effect from these sources by about 10X. Gelatin, a natural product, used as the binder component in the coated layers of the original product has been replaced with a synthetic polymer. this means that the composition and performance of EBT2 film can be more tightly controlled from lot to lot.
Use Gafchromic® EBT2 as a drop-in replacement for EBT. Using the marker dye feature is not mandatory; it will only make things better.
Like the original film, EBT2 can be cut, immersed in water and cleaned with water or alcohol. Expose the film, digitize it with a color scanner and use the response in the red color channel for your dosimetry. Vidar Dosimetry Pro with red LED’s can also be used. The yellow marker dye will not interfere.
The response of Gafchromic® EBT2 film is shown in Figure A. This depicts the response of the film at doses up to 300cGy when measured in transmission using the red color channel of an Epson 10000XL scanner with transparency adapter. Like it’s predecessor, the response of EBT2 is dependent on orientation. Therefore all films must be scanned in the same orientation. We recommend scanning in landscape orientation since this allows the flatness of the scanner response to be assessed by scanning an unexposed film. The image of the unexposed film can be normalized to the average value thus generating an image that can be used to correct images for scanner flatness. If film is cut into smaller pieces it is very important to mark the film pieces so their orientation is known with respect to the original film. This will help in assuring that all films are scanned in the same orientation.
|
