Dosimetry of shaped electron fields using a radial integration method.
The feasibility of an analytical approach to calculate monitor units for shaped electron fields is investigated. A radial integration method is used to calculate the dose at prescription depth from an average output factor and an average depth dose. This concept, as implemented in a commercial planning system, has been tested on various arbitrary fields, and 66 shaped electron fields clinically used for head and neck, chestwall, internal mammary, breast boost, and skin lesions. The measured and prescribed doses agreed within 3.5% or better for 71% of all clinical fields tested; for 91% the agreement was 5.5% or better. The greatest discrepancy (-7.2%) was found for a narrow, long internal mammary field. All treatments were administered on a linear accelerator with electron energies between 6 and 20 MEV.
Muller-Runkel
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Saint Margaret Mercy Health Care Centers, Oncology Center, Hammond, IN 46320.
D004583:Electrons; D011829:Radiation Dosage