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I was wondering if someone can help me out with this physics question. Which answer is correct?
Radiation Physics Question
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Shown is a 10x10 field with 30 degree wedge prescribed to 100 cGy at the isocenter (red crosshairs in the middle). 248 MU is applied.
Now there are two 10x10cm fields (overlapping in green)--one field is open and the other has a 60 degree wedge (seen below). The beams were set to equal dose at the isocenter. The open field has 69 MU and the 60 degree wedged field has 168 MU. The angle of the isodose lines is now steeper.
The third option is the same two 10x10cm fields (again overlapping in green), one open and one with 60 degree wedge. They are prescribed to equal MUs at the isocenter. Both fields have 98MU each.
I'm beginning to like Chartreuse Wombat's answer here--none of the above. Neither of the dose prescriptions using open and 60 degree wedge fields are exactly the same as the 30 degree wedge field. However, the equal MU option does seem to be the closest answer.
Now there are two 10x10cm fields (overlapping in green)--one field is open and the other has a 60 degree wedge (seen below). The beams were set to equal dose at the isocenter. The open field has 69 MU and the 60 degree wedged field has 168 MU. The angle of the isodose lines is now steeper.
The third option is the same two 10x10cm fields (again overlapping in green), one open and one with 60 degree wedge. They are prescribed to equal MUs at the isocenter. Both fields have 98MU each.
I'm beginning to like Chartreuse Wombat's answer here--none of the above. Neither of the dose prescriptions using open and 60 degree wedge fields are exactly the same as the 30 degree wedge field. However, the equal MU option does seem to be the closest answer.
