Fluke Biomedical 37-040 - Manual (Page 5)

Introduction
GAFCHROMIC Dosimetry Media
1
1-1
Section 1
Introduction
1.1 GAFCHROMIC™
Dosimetry Media
• Sensitive to Gamma, Electron, X-ray, Deep
uv and Ionizing Radiation
• Self developing - no processing
• White light insensitive
• Dose rate independent
• Easy to use
1.2 Description
GAFCHROMIC Dosimetry Media has been
developed for use with ionizing radiation. The
indicating film does not require any processing to
develop or fix the image; the image is available for use immediately after the exposure has been
completed.
The GAFCHROMIC Dosimetry Media is particularly useful for routine dosimetry, dose mapping, beam
profiling and high-resolution radiography.
Exposed and unexposed dosimetry media has remarkable stability. Nevertheless, since there is no step
analogous to the fixing step whereby unexposed silver halide is removed from conventional film, the film
remains active indefinitely.
GAFCHROMIC dosimetry media have a 7-micron radiation sensitive layer on a 4-mil polyester base. It is
colorless, grainless and transparent before exposure. The color is a function of the radiation exposure;
higher exposures result in progressively darker blue. This change can be measured accurately (with a
spectrophotometer or other device that measures optical density or absorbance) to calculate applied
dosage.
GAFCHROMIC dosimetry media is composed of materials with low atomic numbers and will not alter the
radiation fields of most products. Further, the material is insensitive to normal room light.
GAFCHROMIC dosimetry media may be used over a wide range of absorbed doses. Typical dose
calibration tables are provided in Tables 1-1 and 1-2 for measurement with a spectrophotometer at 400,
500 and 580 nanometers. (When using a device other than a spectrophotometer the device should be
calibrated using reference dosimeters.) Since there is some post-exposure darkening and changes in
dose/density response at elevated temperatures, care should be taken to adjust readings using Table 1-
4. It is recommended that measurements be taken 24 hours after the end of irradiation. However, Table
1-5 allows for readings made at other times.
These instructions deal with the precautions that should be exercised when using or storing exposed or
unexposed dosimeters/dosimetry film. When optimum storage conditions are maintained, it is believed