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MLC geometry: Varian (millenium MLC)
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120 MLC
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max field size : 40 x 40 cm
- 20 cm : leaf width = 5mm, outside, 1 cm
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maximum overtravel in (IMRT) fields is 14.3 cm:
- so, if an IMRT field width ≥ 14.3 cm splitting beam
-
field width ≈ 28 cm splitting again (‘
carriage positions
’)
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inter-digitating MLC’s
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closing opposing leaf-pairs
20cm
10cm