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. Author manuscript; available in PMC: 2012 Jun 1.
Published in final edited form as: Phys Med Biol. 2009 Aug 18;54(17):5341–5357. doi: 10.1088/0031-9155/54/17/017

Figure 4.

Figure 4

The result of the EBT film calibration process. 69 films were irradiated with doses (or exposure times) spanning from 0 to 25 Gy using a Gamma Knife (60Co) irradiator. Data points: the difference in scan-averaged transmission values, before and after radiation exposure, was correlated to the known radiation dose, averaging over three films which had been exposed simultaneously. Line: A 12th-order polynomial fit described the data well, except in the extreme low-dose region (0–11 cGy), where a linear fit was smoothly matched.