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A totally integrated simulation technique for three‐field breast treatment using a CT simulator
Author(s) -
Butker Elizabeth K.,
Helton Daisy J.,
Keller James W.,
Hughes Lorie L.,
Crenshaw Tim,
Davis Lawrence W.
Publication year - 1996
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.597763
Subject(s) - isocenter , collimator , scanner , tangent , radiation treatment planning , rotation (mathematics) , simulation , computer science , nuclear medicine , imaging phantom , mathematics , physics , optics , computer vision , geometry , medicine , artificial intelligence , radiation therapy , radiology
A method was devised to simulate patients with breast cancer in the actual treatment position utilizing a diagnostic CT spiral scanner, 3‐D Image Workstation for virtual simulation, and a laser coordinate system to transfer planning parameters to the patient's skin. It was desired to produce non‐divergent tangential beams through the lung as well as a matched line for tangential and supraclavicular fields. The patients were immobilized in an Alpha Cradle T M cast. Radio‐opaque markers were placed on the superior, inferior, medial, and lateral margins of the field so as to afford appropriate initial field set‐up approximations. The patient was scanned. The data set was then transferred to the workstation where an isocenter was chosen. The patient was marked. Virtual simulation was then performed. This method employed a half beam technique for the posterior edge of the tangential fields. Table rotation and blocking of the superior margin of the tangential fields were used to produce a vertical edge to match a supraclavicular field. Using a beam's eye view the lateral tangent was matched to the medial exit. A digitally reconstructed radiograph was created to define the tangent fields and place the supraclavicular block. Our initial experience with 50 patients verifies that this is a reproducible and accurate technique. Time required for immobilization and tangential field simulation is approximately 30 minutes. Data is available for 3‐D treatment planning or 2‐D treatment planning on a reconstructed transverse slice angled to match the collimator angle through the patient. Using a CT simulator for simulation of breast cancer affords accuracy of at least equal magnitude to conventional simulators as determined by beam films and ease of set‐up. This technique also affords greater ease in changing treatment parameters without having to resimulate the patient.