title: Evaluating the dose to the contralateral breast when using a dynamic wedge versus a regular wedge.
abstract: The incidence of secondary cancers in the contralateral breast after primary breast irradiation is several times higher than the incidence of first time breast cancer. Studies have shown that the scatter radiation to the contralateral breast may play a large part in the induction of secondary breast cancers. Factors that may contribute to the contralateral breast dose may include the use of blocks, the orientation of the field, and wedges. Reports have shown that the use of regular wedges, particularly for the medial tangential field, gives a significantly higher dose to the contralateral breast compared to an open field. This paper compares the peripheral dose outside the field using a regular wedge, a dynamic wedge, and an open field technique. The data collected consisted of measurements taken with patients, solid water and a Rando phantom using a Varian 2300CD linear accelerator. Ion chambers, thermoluminescent dosimeters (TLD), diodes, and films were the primary means for collecting the data. The measurements show that the peripheral dose outside the field using a dynamic wedge is close to that of open fields, and significantly lower than that of regular wedges. This information indicates that when using a medial wedge, a dynamic wedge should be used.
authors.affiliation: Department of Radiation Oncology, Stanford University School of Medicine, California 94305-5105, USA.
authors.forename: C D
authors.initials: CD
authors.lastname: Weides
authors.forename: E C
authors.initials: EC
authors.lastname: Mok
authors.forename: W C
authors.initials: WC
authors.lastname: Chang
authors.forename: D O
authors.initials: DO
authors.lastname: Findley
authors.forename: C A
authors.initials: CA
authors.lastname: Shostak
mesh_terms: D001940:Breast / Q000528:radiation effects*; D001943:Breast Neoplasms / Q000532:radiotherapy*; D005069:Evaluation Studies as Topic; D005260:Female; D005459:Fluorides; D006801:Humans; D015994:Incidence; D018020:Lithium Compounds; D008961:Models, Structural; D009381:Neoplasms, Radiation-Induced / Q000209:etiology; D016609:Neoplasms, Second Primary / Q000209:etiology; D010315:Particle Accelerators; D011835:Radiation Protection / Q000295:instrumentation; D011879:Radiotherapy Dosage; D011882:Radiotherapy, High-Energy; D012542:Scattering, Radiation; D013819:Thermoluminescent Dosimetry / Q000295:instrumentation
chemical_list: D018020:Lithium Compounds; C027651:lithium fluoride; D005459:Fluorides