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. Author manuscript; available in PMC: 2014 Jun 21.
Published in final edited form as: Phys Med Biol. 2013 Jun 5;58(12):4357–4366. doi: 10.1088/0031-9155/58/12/4357

Table 5.

Out-of-field measurements for a 15×15 cm2 18 MV beam in a phantom as a function of distance from the radiation field edge. Bolus thickness: 3.5 cm, MU: 300 MUs, SSD: 100 cm.

Distance from
field edge (cm)		 Ionization
chamber (cGy)		 KCl:Eu2+ (in-field
calibration) (cGy)		 KCl:Eu2+ (outside-field
calibration) (cGy)		 Error
(cGy)
10 4.80 6.21±0.27 4.80±0.21 N/A
20 1.61 2.22±0.16 1.72±0.12 0.11
30 0.67 0.97±0.06 0.75±0.05 0.08
40 0.42 0.69±0.03 0.53±0.02 0.11
48.5 0.25 0.39±0.01 0.30±0.01 0.05