Evaluation of the Informational Content of Setup Verification Images for Patients Receiving Breast Radiation Therapy (Anterior EPI)

• To measure the difference in accuracy of a breast imaging protocol that includes a large anterior EPI in detecting set-up errors outside of tolerance as compared to the current standard breast imaging protocols. [ Time Frame: Will be measured on days 1, 2 and 3 of radiation therapy and possibly day 4 if adjustments of the EPI where required. ] [ Designated as safety issue: Yes ]
  

• What effect does the addition of a larger anterior EPI have on detection of setup errors in the medial/lateral, anterior/posterior, or superior/inferior directions and at what frequency do these errors occur in clinical practice. [ Time Frame: Will be measured on days 1, 2 and 3 of radiation therapy and possibly day 4 if adjustments of the EPI where required. ] [ Designated as safety issue: Yes ]
  

Radiation: Anterior electronic portal images (EPI)
EPI's are taken for the first three consecutive days of treatment to detect set-up errors.

Accurate patient positioning is critical in Radiation Therapy. Electronic imaging is used to compare a patient's actual treatment position, with that which was planned from an initial CT scan. Radiation Therapists compare planned and actual images using analysis software to determine if differences are within acceptable tolerances. At the VIC, we use 3 different breast imaging protocols depending on the patient set-up and treatment technique. Findings from our recent retrospective planning study show that our current electronic imaging protocols miss some clinically significant patient set-up errors, particularly in the medial/lateral direction, and that these errors can be better detected with the use of an anterior image. The purpose of this study is to test these findings prospectively in clinical practice, through the direct comparison of our current protocols with a proposed new protocol, which would include an anterior electronic portal image (EPI).