AbstractID: 8096 Title: A New Treatment Technique to Irradiate Internal Mammary Nodes in Breast
Cancer
A New Treatment Technique to Irradiate Internal Mammary Nodes in
Breast Cancer
Wide tangential breast fields and internal mammary field (IMF) techniques are common techniques to
irradiate internal mammary nodes (IMN). However, none of these techniques can achieve adequate heart
and lung sparing without compromising target coverage. We report a simple new technique, which can
substantially reduce the volumetric dose of heart and lung while improving target coverage. The new
technique is an optimized combination of the wide tangent and the IMF technique. The wide tangents setup
is used in the first 1/3 fractions, and the IMF technique is used in the remaining fractions. The IMF field is
exclusively an electron beam, matched with two opposing narrow tangents. The lateral tangent is angled
3°~5° medial to optimize the match of the electron and photon fields. Our treatment planning system
(FOCUS, CMS) was used to compare the new technique with the prior techniques (technique of IMF fields
of photon + electron, and technique using wide tangent exclusively). The new technique showed a
substantial reduction of heart and lung volumes receiving high doses, and better IMN coverage compared
to the wide tangent technique. In addition, the new technique showed a substantial volume reduction of
lung and heart at low dose, and significant reduction of “cold” and “hot” spots along the match line,
compared to IMF technique. FILM dosimetry has also been used to verify the treatment planning results.