Reference #2 (Mantel Field)
Attached is a diagram showing a sample lung field. The field is shown approximately full scale at the
skin surface. Please calculate the monitor units or time set to deliver 180 cGy (90 cGy form each field) at
midline on the central axis as well as the total doses to points A-C at the
depths (d) given for each point. Changes in SSD due to patient contour are
indicated at each point the parameter ‘z’ . ‘z’ is positive if the skin surface is farther form the
source relative to the SSD along the central axis, an negative if the skin
surface is closer to the source than this reference point.
Please show all computational details in a
step-by-step fashion and define all factors used. Again, please calculate
treatment time and dose to off axis points as if this was an actual patient,
using your standard dosimetry calculation. If calculations for irregular fields
are normally performed on a computer, please run this program and include a
copy of the output along with the hand calculations performed. Also, be sure to
include the off-axis factors used for points off the central axis regardless of
how you calculate doses to these points.
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Lung |
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