User manual

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film with 150 MU at each position. Note: The ideal dose to the film for
each beam is 100200 cGy. Adjustment of MU should be made to achieve
the aim.
7. Separate the slabs. Take the one to which the film is attached and use a
fine-tip pen, a ruler and the marks on the slab (see Step 4) transfer the
transverse line indicating isocenter height to the edges of the film.
Remove the film from the slab and proceed to Scanning and Star shot
Image Analysis, Step D1. Note: The gantry star shot should look similar to
Figure 1 Because the exposure source was closer to one end of the film
than the other when each line was exposed each of the beam lines is
darker at one end than the other.
Figure 1: Gantry star shot