Gafchromictm ebt4 is designed to measure the absorption dose of ionizing radiation。It particularly applies to high-energy photons。The dynamic range of the film is designed to achieve optimal performance within the dose range of 0. 2 to 10 gy for many applications in imrt, vmat and close-range radiotherapy。For dose measurements well above 10 gy, ebtxd or md-v3 are preferred, while hd-v2 is used for higher dose measurements。
Purpose:Patient qa: imrt, vmat, close-range radiotherapy
Machine quality assurance:Star shot test, picket fence test, flattening and symmetry test
RecommendationsDose range:0. 2 gy to 10 cgy
Recommended energy range:Range 100kev to mv
Structure:The film consists of an active layer with a nominal thickness of 28 μm and is between two 125 μm dumb polyester materials。The active layer contains active components, labeled dyes, stabilizers and other components, giving membranes a near energy-neutral response。The thickness of the active layer varies slightly between production batches。
The main technical features of gafchromictm ebt4 include:
• best dose range: 0. 2 gy to 10 gy, most suitable for imrt and vmat applications
• real-time visibility without exposure
• energy dependence: the smallest difference in response from 100 kv to mv
• close to organizational equivalence • high spatial resolution — can identify features as low as 25 μm or less
• new proprietary technologies to mark dyes in active layers
- uneven correction using multichannel dosimetry
- reduced ultraviolet/visible light sensitivity
• maintain stability at temperatures up to 60°c (140°f)
The integration of yellow-marked dyes in ebt4 with rgb film scanners and filmqapro software 1-3 allows the dose determination process to benefit from the application of three-channel dose determinations。
Gafchromictm ebt4 film
Configure:Active layer (28 μm) between 125 μm dumb surface polyester materials
Dimensions:8 "x 10" or 13 "x 17"
Best dose range:0. 2 gy to 10 gy
Energy dependency:Single 25 gy dose and 5 cumulative 5 gy dose net photodensity difference < 30%
Dose rate response:10 gy exposure net photodensity differential < 5% at 3. 4 gy/min and 0. 034 gy/min
Light stability:Change in light density per 1000 ux-day < 5 x 10-3
Stability in the dark (pre-exposure stability):23 °c (74 °f) < 5 x 10-4 degrees photodensity change/day, < 2 x 10-4 degrees density change/day at cooling days
Evenity:The average sensitivity response is better than 3%;Flimqaprotm and 3-channel dosage measurements were more uniform than ±2%
Like all other gafchromictm films, the ebt4 dosage determines that the film can be treated for short periods of time under indoor light without significant effects。However, it is suggested that films should not be exposed to indoor light for hours and that they should not be used in the dark。When the active ingredient in the ebt4 film is exposed to radiation, it reacts to form a blue polymer with a maximum absorption wavelength of approximately 633 nm。
Gafchromictm ebt4 dosimetric film is recommended for use with a 48-bit (16-bit) tablet colour scanner。Epson eThe xpression 12,000xl photo scanner and the now defunct 11,000xl and 10000xl photo scanner are recommended models。These are colour scanners, which measure the red, green and blue weights of the light transmitted at 16-bit depths per channel。These epson scanners are specifically recommended because of their large scanning area。