Introduction
The introduction of electron Monte Carlo (eMC) into clinical practice was over a decade ago (~2006). Many clinics have adopted eMC as the standard calculation algorithm over less accurate algorithms like Gaussian Pencil Beam. Surprisingly, however, not all clinics that use eMC use the MU that it provides. A 2016 survey of the MedPhys listserve showed that nearly half of the respondents used the MU generated from hand calculations for delivering the patient’s treatment. Yet, the physician was presented the isodose curves based on the MU generated by eMC in ~75% of those clinics.
In my clinic, we were using the hand calculated MU for treatments and were not generating isodose plans at all. EMC usually gave MU that were 5-15% higher than the hand calculated MU. We were reluctant to use the eMC MU. One day, the radiation oncologist noted that the electron patients were not getting “red enough” and we had an “aha” moment. We figured if she wanted them redder, we should use higher MU. EMC was giving higher MU and we thought let’s just use the higher MU from eMC.
Her comments prompted the following study to show that eMC was delivering the correct dose with the higher MU.
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