January 1, 2014.
In x-radiography, filters are often used in order to improve the overall image quality. Filters achieve this by making the x-ray beam have less energy spread, resulting in a cleaner image. Step wedges of different materials were used to compare radiographic density with and without a copper filter to identify the effect of the copper filter at different energies and exposure times. The step wedges used were CRS 1018 (cold rolled steel), Stainless Steel 304L, Al 1100, Al 6061 T6, titanium, copper, PTFE (polytetrafluoroethylene or Teflon), brass, carbon, magnesium, phenolic, tungsten, and tantalum. Out of the 14 step wedges tested, only 12 produced useful data, as tungsten and tantalum were both too dense to produce any useable images and data points. In the given time, we were able to run a total of 6 different series of tests at the following parameters: 130kV for 15min, 130kV for 5min, and 70kV for 5min; all with and without a copper filter. From the resulting data we were able to identify certain trends and patterns of the copper filter that held true across all materials. In every case the use of a copper filter lowers the radiographic density of every step on every material under any conditions.
Sandia National Laboratory/California (SNL)
This material is based upon work supported by the S.D. Bechtel, Jr. Foundation and by the National Science Foundation under Grant No. 0952013. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the S.D. Bechtel, Jr. Foundation or the National Science Foundation. This project has also been made possible with support of the National Marine Sanctuary Foundation. The STAR program is administered by the Cal Poly Center for Excellence in Science and Mathematics Education (CESaME) on behalf of the California State University (CSU).