a tumour located at a depth of 10 cm is treated using a non-isocentic technique with...

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Physics

a tumour located at a depth of 10 cm is treated using anon-isocentic technique with a Co-60 machine, to a dose of 1.8 Gy,with a single 5cm x 5cm beam. Compute the maximum dose receivedanywhere in the patients anatomy.
b)At what depth does the maximum occur? Explain
c) compute the dose at a depth of 5 cm along the beam axis
d) Would this be a good strategy? Explain
percent dose (in %) table for Co-60 beam for different depthsand field sizes
Field size (cm^2) 5x5 10x10 20x20
Depth (cm)
0.5 100 100 100
5.0 76.7 80.4 83.0
10.0 53.3 58.7 63.3

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4.1 Ratings (544 Votes)

solution aAttached Table Field Size in cm2 5 x 5 10 x 10 20 x 20 Depth in cm 05 100 100 100 501 7672 8040 832 100 536 5874 6338 this a table of PDD data bCobalt 60 is produced in a nuclear reactor by bombarding 59Co with neutrons It has a half life of 53 years and decays by negative beta emission to metastable 60Ni This rapidly releases a gamma ray of either 117 or 133 MeV to reach a stable stateThe source typically has an activity of 185 370 MBq giving a dose rate at 80 cm of 1 2 Gyminute The Cobalt 60 source is usually replaced before a single half life has elapsed cThe source is See Answer

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	Field size (cm^2)	5x5	10x10	20x20
Depth (cm)
0.5		100	100	100
5.0		76.7	80.4	83.0
10.0		53.3	58.7	63.3