Forward-planned intensity modulated radiation therapy using a cobalt source: A dosimetric study in breast cancer

• Main Authors: Savino Cilla, Joseph Kigula-Mugambe, Cinzia Digesù, Gabriella Macchia, Solomon Bogale, Mariangela Massaccesi, David Dawotola, Francesco Deodato, Milly Buwenge, Luciana Caravatta, Angelo Piermattei, Vincenzo Valentini, Alessio G Morganti
• Format: Article
• Language: English
• Published: Wolters Kluwer Medknow Publications 2013-01-01
• Series: Journal of Medical Physics
• Subjects: Breast neoplasms; cobalt machine; intensity-modulated radiotherapy; radiotherapy
• Online Access: http://www.jmp.org.in/article.asp?issn=0971-6203;year=2013;volume=38;issue=3;spage=125;epage=131;aulast=Cilla

This analysis evaluates the feasibility and dosimetric results of a simplified intensity-modulated radiotherapy (IMRT) treatment using a cobalt-therapy unit for post-operative breast cancer. Fourteen patients were included. Three plans per patient were produced by a cobalt-60 source: A standard plan with two wedged tangential beams, a standard tangential plan optimized without the use of wedges and a plan based on the forward-planned "field-in-field" IMRT technique (Co-FinF) where the dose on each of the two tangential beams was split into two different segments and the two segments weight was determined with an iterative process. For comparison purposes, a 6-MV photon standard wedged tangential treatment plan was generated. D mean , D 98% , D 2% , V 95% , V 107%, homogeneity, and conformity indices were chosen as parameters for comparison. Co-FinF technique improved the planning target volume dose homogeneity compared to other cobalt-based techniques and reduced maximum doses (D 2% ) and high-dose volume (V 110% ). Moreover, it showed a better lung and heart dose sparing with respect to the standard approach. The higher dose homogeneity may encourage the adoption of accelerated-hypofractionated treatments also with the cobalt sources. This approach can promote the spread of breast conservative treatment in developing countries.